JPS63217239A - Temperature measuring instrument - Google Patents

Abstract

PURPOSE:To obtain a measuring instrument which is manufactured and installed economically by performing temperature measuring operation at plural places which are equal in the length of external wiring by two-wire type resistance bulbs and one DC power source. CONSTITUTION:A series circuit 10 is constituted by connecting one comparison part B and plural two-wire type temperature measurement parts A1-An where the external wiring is connected to both-terminal sides of two-wire type resistance bulbs S1-Sn in series. A constant current generating means 11 flows a constant current to the series circuit 10. A voltage measuring means 15 measures respective voltages based upon fed constant currents of the comparison part B and temperature measurement parts A1-An. Then an arithmetic means 16 performs specific arithmetic as to the voltage measurement result of the voltage measuring means 15 to measure temperatures detected by the resistance bulbs S1-Sn according to the result. Then the temperature measurement parts A1-An have temperature measuring resistance elements R1-Rn which are equal in reference resistance value and external wiring coils R11, R12-Rn1, and Rn2 which are equal in resistance value, and the comparison part B is constituted by connecting two series-connected external wiring coils Rc1 and Rc2 and a 1st resistor Rc which has a resistance value equal to a reference resistance value and no temperature dependency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an industrial electric temperature measuring device that measures temperatures at multiple locations requiring external wiring with approximately equal resistance values;
In particular, it relates to a device that can be manufactured and installed economically.

[Conventional technology]

Conventionally, in electrical temperature measuring devices using a resistance temperature detector, VC is used to economically prevent temperature measurement errors due to the resistance of external wiring connecting the resistance temperature detector and the resistance measurement circuit.
1 Three-wire temperature measuring device is widely used industrially.
The figure is a configuration diagram showing an example of this temperature measuring device.
2 is a three-wire resistance temperature measuring element, and 2 is a three-wire resistance temperature measuring element constituting the resistor l. As can be seen from the figure, a first internal conducting wire 3a and a second internal conducting wire 3b are drawn out from one end of the resistive element 2 and connected to a first terminal 4a and a second terminal 4b, respectively. Further, a third internal conducting wire 3C is drawn out from the other end of the resistance element 2 and connected to a third terminal 4C. 5 is a protection tube that accommodates the element 2, conducting wires 3a to 3C, and terminals 4a to 4C, and the temperature sensing resistor l is made up of the above-mentioned element 2, conducting wires 3a to 3C, terminals 4a to 4C, and capacitor g5. It is configured.

6, the temperature detected by the resistance element 2 was measured by measuring the electrical resistance of the resistance element 2.

In the bridge circuit as a resistor 6111 constant circuit, as shown in the figure, the terminal 4a of the resistance temperature detector l is connected to the DC power supply 7 of the circuit 6 via the first external wiring 8a, and the terminals 4be 4C of the resistor 1 are connected to each side of the bridge in the bridge circuit 6 via the second external wiring 8b and the E3 external wiring 8C, respectively.

In Figure 3, the resistance temperature detector l must naturally be installed at the temperature measuring location, but the bridge circuit 6 is usually installed in a location with better environmental conditions than the location where the resistor l is installed. In industrial temperature measurement, it is often necessary to install the bridge circuit 6 at a considerable distance from the resistance temperature detector 1. Therefore, in such a case, the external wiring 88 to
The resistance value of wire 8c is quite large, but in FIG. 3, wires 8a to 8C are incorporated into the resistance measurement circuit as shown, so even if the resistance value of wires 8a to 8C becomes large, these The resistance value does not affect the temperature measurement results.

[Problem that the invention seeks to solve]

The temperature measuring device shown in Fig. 3 is configured as described above and can only measure the temperature at one location.

Industrially, for example, two-dimensional temperature distribution within a cylindrical fluid storage tank is measured.

Cases often arise in which it is necessary to measure temperatures at multiple locations in a narrow, localized area. Therefore, in such a case, when trying to measure temperature using a resistance temperature sensor, it would be economical if a temperature measuring device u4 could be constructed that can share the DC power supply 7 mentioned above for a large number of temperature measuring points. However, it is necessary to constantly supply a measurement current to the resistance temperature detector in order to prevent self-heating errors, and the resistance of the wiring connecting the resistance temperature detector and the resistance measurement circuit may cause problems. Due to the need to prevent the occurrence of temperature measurement errors, it is necessary to prepare as many temperature measurement devices as shown in FIG. 3 as required.

In other words, conventionally, when trying to measure degrees Celsius using temperature measuring resistors at multiple locations, even when the temperature measuring locations are within a narrow, localized range, the three-wire temperature measuring device shown in Figure 3 is used to measure temperature. As a result, it is necessary to prepare a plurality of DC power supplies 7, and in this case, the number of external wires connecting the resistance temperature detector and the resistance measurement circuit also increases. Therefore, there is a problem in that the temperature measuring device cannot be manufactured and installed economically.

The above explanation was for the case where the resistance of the resistance temperature detector l was measured by the bridge type measuring circuit 6, but when the resistance was measured by the potentiometer type measuring circuit, the number of temperature measuring points in the measuring circuit is equal to the number of temperature measuring points. Since it is necessary to prepare as many units as possible, it is necessary to prepare according to the number of temperature measurement points such as DC constant voltage power supply and external wiring.In the end, when using the potentiometer measurement method, the same method as for the bridge measurement method described above is used. There was a problem.

It is an object of the present invention to make it possible to measure temperatures at multiple locations where the length of external wiring is the same as described above using a two-wire resistance temperature detector and one DC power supply, thereby reducing manufacturing and installation costs. The objective is to obtain a temperature measuring device that can be used to measure temperature.

[Means for solving problems]

In order to solve the above problems, according to the present invention, one comparing section and a plurality of two-wire temperature measuring sections each having an external wiring connected to both terminals of a two-wire temperature measuring resistor are connected in series. a series circuit connected to the series circuit, a constant current generating means for flowing a constant current through the series circuit, a voltage measuring means for measuring each voltage (based on the constant current supply to the comparing section and the temperature measuring section, and a calculating means for performing a predetermined calculation in degrees Celsius on the voltage measurement result by the measuring means, and measures the temperature detected by the resistance temperature sensor based on the calculation result of the calculating means, and each of the temperature measuring parts It has a temperature measuring resistance element having an equal reference resistance value and the external wiring having an equal resistance value, and the comparison section has two external wirings connected in series and a resistance temperature sensor having a resistance value equal to the reference resistance value and temperature dependence. C. temperature measuring device is constructed by connecting the first resistor in series with the first resistor having a resistance value of zero.

[Effect]

With this configuration, the constant current generated by the constant current generating means flows through the temperature measuring section, even if there is a diode, as long as there is no disconnection in the two-wire temperature measuring section. Since a constant current flows through the comparison section, based on the constant current of the two-wire temperature measurement section obtained by the voltage measurement means, (
When the voltage based on the current of the comparison section, which is also obtained by the voltage measuring means, is subtracted from the voltage by the calculating means, the result of this subtraction becomes a voltage corresponding to the temperature detected by the resistance temperature sensor. Therefore, by causing the calculation means to again perform a predetermined calculation on the voltage resulting from this subtraction, the temperature detected by the temperature-measuring resistor can be determined. This temperature measuring device has a two-wire temperature measuring section and requires only one constant current generating means for multiple temperature measuring sections, so it can be manufactured and installed economically. it is obvious. In addition, if there is a diode,
Temperature measuring section short-circuited by this diode (even if a disconnection occurs, the constant current will flow through the diode and the series circuit will not become disconnected, so the effect of the disconnected temperature measuring section will affect the temperature measurement operation of other temperature measuring sections) It is possible to obtain a temperature measuring device that does not exceed

〔Example〕

FIG. 1 is a block diagram of a first embodiment of the present invention.

In the figure, R8-Rn is a two-wire resistance temperature sensor S1-5n
TI,, T'S! for each resistance temperature sensing element in rc. ~
Tnl.

Tnz are terminals of the resistors 81 to SnK, respectively. Qu, G, t-Gnx+ Gnz are each resistor S
This is an internal conductive wire from i to Sn. Terminal T■・Tl! ~
Tnx Tnz is the terminal F'He Pi of the resistance measurement circuit 9
! ~Fnt, Fnz external wiring R1s* R
tm ~ Rnxs Rnz ic. Rc1*Rc2 are terminals Fct connected in series and provided at both ends of the resistance measuring circuit 9, respectively.

Fc2IIC are connected to external wiring, A1 is a two-wire temperature measuring section consisting of resistance temperature detector S1 and external wiring R,,,R,, A is resistance temperature detector S1 and external wiring R11°R1
! An is a two-wire temperature measuring section consisting of a temperature measuring resistor Sn and external wirings Rnt and Rn2.

Rc is located inside the resistance measuring circuit 9 and one end is connected to the terminal FC2.
K connected. This is a first resistor having a temperature-independent resistance value to be described later, and is a comparison section consisting of a resistor Rc connected in series with B+ as described above, and external wirings RC1 and RC2. The temperature measurement units 1 to An and the comparison unit B are connected to 5 in the resistance measurement circuit 9 as shown in the figure to form a °C series circuit 10.

11 is a constant current generating means that causes a constant current I to flow through the series circuit IO, and SW, ~SWn and 8Wc are terminals F, respectively.
The amplifier circuit is a switch that opens and closes the connection between each of ll~Fnx and Fct and the input terminal 12a of the amplifier circuit 12. 2 is configured to output an output signal 12b corresponding to the electric power EEK input to the terminal 128. 1
3 is a switch control circuit k14t-L that controls the opening and closing of the switches SW, ~SWn, and SWc according to the input timing signal 14bK, and outputs the timing signal 14b according to the procedure described later, and then outputs the input output signal 12b.
This is a control storage section that performs calculations to be described later and stores the results of the calculations. In the figure, since a constant current flows through the series circuit 10, the terminals Fil to Fnt.

For Fcric, voltages V and Vn*Vc appear depending on the resistances of the temperature measuring sections 1 to An and the comparison section B, respectively.

The control storage section then stores this value every time the signal 12b is input, and further stores I'C (Vt Vt) - (Vt
-V, ), ~(Vn-), a difference calculation corresponding to K is performed and the result of this calculation is also stored. here vc
(V, -V,), (V, -V,), ~(Vn-V
c) and Vc +
It is clear that the voltages of I-An and comparison section B are the same. Therefore, SW1 to 8Wn, SWc and amplifier circuit 1
2, the switch control circuit 13, and the control storage section 14, based on the energization of the constant current generators of the temperature measurement sections A1 to An and the comparison section B (
It can be said that voltage measuring means 15 for measuring each voltage is configured. The control storage unit 14 is arranged so that it can output the above-mentioned storage result as a signal 14a.

16 is an arithmetic means to which the signal 14a is input and which performs a predetermined arithmetic operation to be described later on this input signal. Resistance measurement circuit 9 & temperature measurement section A1 to An and external wiring @Rcx, R
It consists of each part shown except for cz and ℃.

In Figure 1, each part is as described above! Since the resistances R and -Rn of the resistance elements each have the reference resistance value R
If it is assumed to be composed of o~R, no and changes due to temperature ΔR1~ΔRn, equation (1) holds true.

Here, the reference resistance values Ro1 to Rno are the resistance element +8. ~R
ΔR1 to ΔRn are resistance values corresponding to temperatures θ and θnK detected by the elements R8 to Rn, respectively. In equation (1), the internal conductor G■l o
, , ~Gnt, Gn2o each resistance is ignored. Also,
As mentioned above, since the resistance Rc is a resistance without temperature dependence, Vc is expressed as in equation (2).

V c= (Rc+Rcx+Rc2) −I
-...(2) Therefore, in FIG. 1, the control storage unit 14 has a voltage difference (V
+-vf), ~.

(Vn-Vc) and a signal 14a corresponding to the voltage Vc is output.

Incidentally, in the case of FIG. 1, the main parts are configured so that equations (3) and (4) hold true. That is, for example,
The resistance temperature detectors s and -an having the resistance temperature detectors R1 to Rn having the same reference resistance value are arranged at the same distance from the resistance measurement circuit 9, and the resistors 81 to S arranged in this way 5 are arranged at the same distance from the resistance measurement circuit 9.
Measurement circuit 91 for n using external wiring R1° to Rnz of the same thickness.
'C connection, and external wiring RCI having the same length and same thickness as external wiring RII to Rnz.

Lay the wiring for RC2 in the same way as ~Rn2, R
This is a case where the first resistor Rc having the same resistance value as the reference resistance value of the resistance elements R1 to R1 is connected in series to the series circuit of CI and Rcz.

R1,=R,@=-・-・=Rno=Rc
------・(3) R11=R1,=R,,
z-----=Rn 1=Rn 2=RC1=RC2・
- (4) It is clear that equation (5) holds true from equations (1) to (4).

In FIG. 1, the calculating means 16 calculates the equation (9) based on the signal 14avc, and further calculates the obtained ΔR1 to Δ
The resistance element R that caused these resistance changes from the RnO value
Signal 16 corresponding to temperature θ detected by 1~RntC, ~θn
It is configured to output a.

Therefore, temperatures 01 to θn can be measured using the power signal 1f58.

In this case, as is clear from the above, the temperature measuring section A1
~An may be of a two-wire type, and one constant current generating means 11 may be provided for these plurality of temperature measuring sections. Therefore, it can be said that the temperature measuring device shown in FIG. 1 is a device that can be manufactured and installed economically.

FIG. 2 is a configuration diagram of a second embodiment of the present invention, and the difference from FIG.
, ~Dn are connected in parallel. Then, in the %wJz diagram, if there is no disconnection in the temperature measurement parts A1 to An, then vc is the voltage across the diode D! ~Dn is smaller than the forward voltage drop, and the diodes D1~Dn are in a non-conducting state;
When a disconnection occurs in any of the temperature measuring sections A, ~An, a voltage higher than the above forward voltage drop is applied to the diode connected to the disconnected temperature measuring section, causing the diode to become conductive. Each part is configured so that Therefore, in the case of Fig. 2, if a disconnection occurs in any of the temperature measuring parts A1 to An, temperature measurement by all other temperature measuring parts becomes impossible (compared to the case of Fig. 1, temperature measuring part A , ~ AnK There is an advantage that even if a wire breakage occurs, temperature measurement can be continued by the temperature measuring section that does not have a wire breakage.The temperature measuring device shown in Fig. 2 is a device that can be manufactured and installed economically. it is obvious.

〔Effect of the invention〕

As described above, in the present invention, C includes one specific soft part and a plurality of two-wire temperature measuring parts each having an external wiring connected to both terminals of the two-wire temperature measuring resistor. A series circuit connected in series with or without a diode connected in parallel, a constant current generating means for flowing a constant current through the series circuit, and each based on the constant current energization of the comparing section and the temperature measuring section. It is equipped with a voltage measuring means for measuring voltage and a calculating means for performing a predetermined calculation in degrees Celsius on the voltage measurement result by the voltage measuring means, and measures the temperature detected by the resistance temperature detector based on the calculation result of the calculating means. hand.

The temperature measurement section has a resistance temperature measurement element having the same reference resistance value and the external wiring having the same resistance value, and the comparison section has two external wirings connected in series and a temperature measurement resistance element having a resistance value equal to the reference resistance value and temperature dependent. The temperature measuring device was constructed by connecting the first resistor in series with the first resistor having a neutral resistance value. As a result, with this configuration, of course, if no diode is present.

As long as there is a diode and there is no disconnection in the two-wire temperature measuring section, the constant current generated by the constant current generating means will flow through the temperature measuring section, and this constant current will also flow through the comparison section, so the temperature value obtained by the voltage measuring means will be When the voltage is subtracted by the arithmetic means from the voltage based on the constant current of the two-wire temperature measuring section, based on the current of the comparison section also obtained by the voltage measuring means, the result of this subtraction is is a voltage corresponding to the temperature detected by the temperature sensor.Therefore, by having the calculation means again perform a predetermined calculation on the voltage resulting from this subtraction, it is possible to know the temperature detected by the resistance temperature sensor. This temperature measuring device M has a two-wire temperature measuring section and requires only one constant current generating means for a plurality of temperature measuring sections. There is an effect that can be performed.

In addition, if there is a diode, the temperature measuring part short-circuited by this diode will be disconnected and the constant current will flow through the diode and the series circuit will not become the Wr line state.
The present invention also has the advantage that the temperature measurement operation of other temperature measurement units is not affected by the disconnected temperature measurement unit.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are block diagrams of a first embodiment and a second embodiment of the present invention, respectively. FIG. 3 is a configuration diagram of a conventional temperature measuring device. 10... Series circuit, 11... Constant current generating means, 15 Denou measuring means, 16... Arithmetic means, A, ~An... Two-wire system Temperature measuring part, B...
・Comparison section, D, ~Dn...Diode, ■...
...Constant current s R1-Rn...Resistance temperature sensor, R11-Rnz, RCl, RC2...
External wiring %Rc...First resistor, J~Sn...
...Resistance temperature sensor, TI, ~Tnz... terminal. ] ；゛￥ Edition 3 Figure

Claims (1)

[Claims] 1) A series circuit in which one comparison section and a plurality of two-wire temperature measurement sections each having an external wiring connected to both terminals of a two-wire resistance temperature sensor are connected in series. , a constant current generating means for flowing a constant current through the series circuit, a voltage measuring means for measuring each voltage based on the application of the constant current of the comparing section and the temperature measuring section, and voltage measurement results by the voltage measuring means. and a calculating means for performing a predetermined calculation, and measures the temperature detected by the temperature measuring resistor based on the calculation result of the calculating means, and each of the temperature measuring parts has a temperature measuring resistor having an equal reference resistance value. and the external wiring having the same resistance value as the element,
and the comparison section is formed by connecting in series two of the external wirings and a first resistor having a resistance value equal to the reference resistance value and having no temperature dependence. measuring device. 2) The temperature measuring device according to claim 1, wherein a diode is connected in parallel to each of the temperature measuring sections.