Multi-channel thermocouple measuring device

Abstract

The present invention relates to a multi-channel thermocouple measuring device, which may include: a thermocouple and a thermistor pair; a terminal section to which analog signals of the thermocouple and thermistor pair are input; and a detection section to convert the analog signals of the thermocouple and thermistor pair input through the terminal section into digital signals.

Description

Technical Field

[0001] This invention relates to a multi-channel thermocouple measuring device, and more specifically, to a multi-channel thermocouple measuring device for cold junction compensation. Background Technology

[0002] Generally speaking, a thermocouple is a device that uses the Seebeck effect to measure a wide temperature range, and due to its excellent durability, it is mainly used in extreme environments such as power plants and steel mills.

[0003] A thermocouple measuring device is a device that uses the electromotive force generated by a thermocouple to measure temperature. The temperature measured here is based on 0°C. Therefore, in practice, the thermocouple sensor compensates by measuring the temperature near the connection point with the measuring device and adding the measured value. This compensation is called reference junction compensation or cold junction compensation.

[0004] The following description, with reference to the accompanying drawings, illustrates an example of a conventional thermocouple measuring device.

[0005] Figure 1 This is a schematic diagram of an existing thermocouple measuring device.

[0006] Reference Figure 1 It includes: a plurality of thermocouples 100; a temperature-sensing resistor 200, which forms a different channel from the plurality of thermocouples 100 and detects the temperature of the contact 310; a detection unit 300, which detects the electromotive force generated in the plurality of thermocouples 100 respectively and converts it into a digital signal; and a compensation unit 400, which adds the temperature detected by the detection unit 300 in the thermocouples 100 to the temperature detected by the temperature-sensing resistor 200 and provides it to the PLC 500, etc.

[0007] The detection unit 300 is a multi-channel structure, comprising: a plurality of contacts 310, which are respectively connected to a plurality of thermocouples 100 and temperature measuring resistors 200; an analog-to-digital converter 320, which converts the current value detected by the contacts 310 into a digital signal; and an insulation unit 330, which insulates the output of the analog-to-digital converter 320 and provides it to the compensation unit 400.

[0008] The insulating part 330 can be equipped with an optocoupler.

[0009] The figure shows a four-channel detection unit 300. That is, four thermocouples 100 are encapsulated in a housing and connected independently, and the two ends of each thermocouple 100 are connected to two contacts 310 respectively.

[0010] The distance between thermocouple 100 and contact 310, and the distance between contact 310 and analog-to-digital converter 320, can be varied depending on the setup environment, etc.

[0011] For cold junction compensation of thermocouple 100, the detection unit 300 uses a temperature-sensing resistor 200 to provide a separate reference contact 311 not connected to thermocouple 100, and cold junction compensation of thermocouple 100 can be performed in the compensation unit 400 by detecting the temperature of the reference contact 311.

[0012] The temperature measuring resistor 200 is a common thermistor.

[0013] The compensation unit 400 may include: a control unit 420 for performing cold junction compensation; a memory 410 for storing data; and an interface 430 for communicating with external devices such as a PLC 500 that uses the detected temperature.

[0014] However, since the temperature measuring resistor 200 used for cold junction compensation is located inside the detection unit 300 in the multi-channel thermocouple measuring device, it will be affected by the heating state of the detection unit over time after initial startup.

[0015] Therefore, existing thermocouple measuring devices typically require a preheating time of more than 30 minutes before the internal temperature of the detection section 300 reaches thermal equilibrium. This preheating time can reduce the cold junction compensation error of the thermocouple 100.

[0016] Furthermore, in the prior art, instead of measuring the temperature of the contacts 310 connected to each thermocouple 100, a reference contact 311 is set up, and the temperature of other contacts 310 is predicted and cold junction compensation is performed by detecting the temperature of the reference contact 311. Therefore, based on the temperature deviation between the reference contact 311 and the contacts 310, accurate compensation may not be possible.

[0017] In view of the above problems, the Korean Patent No. 10-0942139 (Temperature Measuring Device Using Thermocouple Sensor, granted on February 4, 2010) of the applicant of this invention describes a temperature measuring device capable of measuring the temperature of contacts (terminals) connected to thermocouples.

[0018] However, in the aforementioned authorized patents, the manufacturing cost is relatively high because digital temperature sensors are required to detect the temperature, and the increase in material and processing costs is inevitable because new and appropriate terminals need to be developed and manufactured for each channel. Summary of the Invention

[0019] The problem that the invention aims to solve

[0020] In view of the above problems, the objective of this invention is to provide a multi-channel thermocouple measuring device that can reduce the generation of cold junction compensation errors caused by internal temperature deviations.

[0021] Another objective of the present invention is to provide a multi-channel thermocouple measuring device that can detect the temperature of a contact point connected to a thermocouple even without using a digital temperature sensor.

[0022] Another objective of the present invention is to provide a multi-channel thermocouple measuring device that simplifies the terminal structure and enables cold junction compensation regardless of the internal temperature equilibrium state of the measuring device.

[0023] Furthermore, another objective of the present invention is to provide a multi-channel thermocouple measuring device that uses a thermistor to detect the temperature of the contact and facilitates the replacement and maintenance of the thermistor.

[0024] Technical solutions to the problem

[0025] The multi-channel thermocouple measuring device of the present invention, which is used to solve the above-mentioned technical problems, may include: a thermocouple and a thermistor pair; a terminal section to which an analog signal of the thermocouple and thermistor pair is input; and a detection section including a multi-channel analog-to-digital converter that converts the analog signal of the thermocouple and thermistor pair input through the terminal section into a digital signal in the multi-channel analog-to-digital converter.

[0026] In this embodiment of the invention, a compensation unit may also be included, which receives the digital signal from the detection unit and performs cold junction compensation.

[0027] In this embodiment of the invention, a plurality of detection units may be provided, and each plurality of detection units may be housed in a separate housing.

[0028] In this embodiment of the invention, the terminal portion may be located within the detection portion.

[0029] In this embodiment of the invention, the terminal portion may be an external terminal portion located between the detection portion and the thermocouple.

[0030] In an embodiment of the present invention, the thermistor may include: a printed circuit board on which a thermistor chip is mounted; a pair of U-shaped terminals protruding from the printed circuit board; and printed lines that electrically connect each U-shaped terminal to the thermistor chip.

[0031] Invention Effects

[0032] This invention detects the contact temperature of each thermocouple, thereby preventing errors caused by cold junction compensation.

[0033] Furthermore, by using a multi-channel analog-to-digital converter, the electromotive force of the thermocouple and the thermistor that detects the temperature of the thermocouple contacts can be converted into a digital signal using a single analog-to-digital converter. Therefore, the temperature of the thermocouple contacts can be detected even without using relatively expensive digital temperature sensors. This reduces costs, and also has the effect of reducing costs by eliminating the need to design and manufacture additional terminals.

[0034] Furthermore, by moving the position of the contact point, which serves as a compensation reference point, to the outside of the measuring device, the present invention has the effect of preventing errors caused by temperature deviations inside the device, while enabling immediate temperature detection and compensation without additional preheating time.

[0035] In addition, this invention utilizes a thermistor to detect the temperature of the contact and proposes a novel coupling structure between the thermistor and the terminal, which facilitates the replacement, relocation, and maintenance of the thermistor. Attached Figure Description

[0036] Figure 1 This is a block diagram of an existing multi-channel thermocouple measurement device.

[0037] Figure 2 This is a block diagram of a multi-channel thermocouple measuring device according to an embodiment of the present invention.

[0038] Figure 3 This is a block diagram of a multi-channel thermocouple measuring device according to another embodiment of the present invention.

[0039] Figure 4 This is a structural diagram of a thermistor.

[0040] Explanation of reference numerals in the attached figures

[0041] 10: Thermocouple 20: Thermistor

[0042] 21: Printed Circuit Board; 22: Thermistor Chip

[0043] 23: U-shaped electrode 24: Printed circuit board

[0044] 30: First Detection Department; 33: Multi-channel Analog-to-Digital Converter

[0045] 40: Compensation section; 60: External terminal section

[0046] 61: First terminal section; 62: Second terminal section Detailed Implementation

[0047] To fully understand the structure and effects of the present invention, preferred embodiments are described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be embodied in various forms and with various modifications. The description of these embodiments is provided only to fully disclose the present invention and to fully disclose the scope of the invention to those skilled in the art. In the drawings, the constituent elements are shown at an enlarged scale for ease of explanation, and the ratios of the individual constituent elements may be enlarged or reduced.

[0048] The terms "first," "second," etc., are used to describe various constituent elements; however, the constituent elements should not be limited by these terms. These terms can be used to distinguish one constituent element from another. For example, without departing from the scope of the invention, "first constituent element" can be named "second constituent element," and similarly, "second constituent element" can be named "first constituent element." Furthermore, unless the context clearly specifies otherwise, singular expressions include plural expressions. In embodiments of the invention, unless otherwise defined, the terms used can be interpreted as meaning commonly understood by those skilled in the art.

[0049] Hereinafter, a multi-channel thermocouple measuring device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0050] Figure 2 This is a block diagram of a multi-channel thermocouple measuring device according to a preferred embodiment of the present invention.

[0051] Reference Figure 2 The present invention includes: a first detection unit to a fourth detection unit 30, 30-1, 30-2, 30-3, which are respectively connected to a thermocouple 10, 10-1, 10-2, 10-3 and a thermistor 20, 20-1, 20-2, 20-3, and detect the temperature of the thermocouples 10, 10-1, 10-2, 10-3 and the thermistors 20, 20-1, 20-2, 20-3 connected to each detection unit, and convert the temperature into a digital signal; and a compensation unit 40, which compensates for the cold junction temperature of the thermocouples detected by the first detection unit to the fourth detection unit 30, 30-1, 30-2, 30-3 and provides it to an external device 50.

[0052] The characteristic structure and function of the multi-channel thermocouple measuring device of the present invention, as described above, will be explained in more detail.

[0053] First, the present invention divides the structure of the detection unit according to the channels, and constructs the first detection unit to the fourth detection unit 30, 30-1, 30-2 and 30-3 for the four channels.

[0054] In essence, the first to fourth detection units 30, 30-1, 30-2, and 30-3 are separated by different housings, thereby minimizing the occurrence of internal temperature deviations in the device.

[0055] The specific configurations of the first to fourth detection units 30, 30-1, 30-2, and 30-3 can all be identical. Therefore, in the description of this invention, only the first detection unit 30 can be described as needed. Even without a separate description of the second to fourth detection units 30-1, 30-2, and 30-3, it can be understood that they perform the same function as the first detection unit 30.

[0056] In each of the first to fourth detection units 30, 30-1, 30-2, 30-3, a thermocouple 10, 10-1, 10-2, 10-3 is connected to a contact 31, 31-1, 31-2, 31-3, and a thermistor 20, 20-1, 20-2, 20-3 is connected to a reference contact 32, 32-1, 32-2, 32-3.

[0057] The first detection unit 30 may be provided with an amplification section that amplifies the electromotive force of the thermocouple 10 and the electromotive force of the thermistor 20 respectively. The configuration of the amplification section is omitted in the figure.

[0058] The electromotive force of the thermocouple 10 and the thermistor 20 is an analog signal, which is input to the multi-channel analog-to-digital converter 33, converted into a digital signal, and output through the insulating part 34.

[0059] The contact 31 and the reference contact 32 are positioned adjacent to each other, and the temperature difference between them can be minimized.

[0060] Therefore, the first to fourth detection units 30, 30-1, 30-2, and 30-3 can respectively output the temperature information detected by the thermocouples 10, 10-1, 10-2, and 10-3 connected to them, and the temperature information of the contact points detected by the thermistors 20, 20-1, 20-2, and 20-3 connected to them.

[0061] The outputs of each of the first to fourth detection units 30, 30-1, 30-2, and 30-3 are provided to a compensation unit 40.

[0062] The compensation unit 40 may include: a control unit 41, which performs cold junction compensation according to a given program; a memory 42, which stores data; and an interface 43, which communicates with an external device 50.

[0063] Specifically, the preset parameters of the external device 50 can be received through the interface 43 and stored in the memory 42. While performing cold junction compensation, the control unit 41 judges the signals of the first detection unit to the fourth detection unit 30, 30-1, 30-2, and 30-3 according to the parameters, and performs control such as changing the reference value of the multi-channel analog-to-digital converters 33, 33-1, 33-2, and 33-3.

[0064] Based on the above configuration, the present invention can individually detect the temperature of the contacts 31, 31-1, 31-2, and 31-3 of each thermocouple 10, 10-1, 10-2, and 10-3, thereby preventing errors caused by cold junction compensation.

[0065] Furthermore, by employing multi-channel analog-to-digital converters 33, 33-1, 33-2, and 33-3 respectively, it is not necessary to use digital temperature sensors to detect the temperatures of reference contacts 32, 32-1, 32-2, and 32-3. Moreover, it has the characteristic that the temperatures of reference contacts 32, 32-1, 32-2, and 32-3 can be detected using relatively inexpensive thermistors 20, 20-1, 20-2, and 20-3.

[0066] Figure 3 This is a block diagram of a multi-channel thermocouple measuring device according to another embodiment of the present invention.

[0067] Reference Figure 3 This allows the temperature detection contact of the thermistor 20 to be located outside rather than inside the first detection unit 30. The second to fourth detection units 30-1, 30-2, and 30-3 are omitted in the accompanying drawings.

[0068] The external terminal portion 60 includes a first terminal portion 61 connected to the thermocouple 10 and a second terminal portion 62 connected to the thermistor 20, and is located between the thermocouple 10 and the first detection portion 30. The first terminal portion 61 and the second terminal portion 62 are located adjacent to each other.

[0069] Since the external terminal portion 60 is located outside the first detection portion 30, even if there is a difference in the position of the first terminal portion 61 and the second terminal portion 62, no temperature deviation will occur.

[0070] Additionally, the contact temperature at a location relatively close to the thermocouple 10 can be detected. It is well known that detecting the temperature of the connection point between the thermocouple 10 and the signal line is the most accurate method for cold junction compensation.

[0071] Therefore, the present invention positions the external terminal portion 60 close to the thermocouple 10, and detects the temperature of the external terminal portion 60 by installing a thermistor 20 at an adjacent position, thereby improving the accuracy of cold junction compensation.

[0072] At this time, the position of the external terminal 60 is not directly affected by the temperature of the heating element, which is the object of temperature measurement.

[0073] The first detection unit 30 receives the electromotive force of the thermocouple 10 and the thermistor 20 through the external terminal unit 60 and the signal line, converts it through the multi-channel analog-to-digital converter 33, and sends it to the compensation unit 40 through the insulation unit 34.

[0074] The multi-channel analog-to-digital converter 33 can not only convert the electromotive force of the thermocouple 10 into a digital signal, but also convert the electromotive force of the thermistor 20, which is the same analog signal, into a digital signal.

[0075] Therefore, cold junction compensation can be performed even without using a digital temperature sensor.

[0076] Figure 4 This is an embodiment of the external terminal portion 60 and the thermistor 20 coupled to the external terminal portion 60.

[0077] like Figure 4 As shown, the external terminal section 60 provides four terminals, such that two terminals function as a pair, allowing the thermocouple 10 and the thermistor 20 to be connected simultaneously.

[0078] That is, as described above, it includes: a first terminal portion 61 for connecting the thermocouple 10 and having two terminals; and a second terminal portion 62 for connecting the thermistor 20 and having two terminals.

[0079] The first terminal portion 61 and the second terminal portion 62 can each use a bolt terminal type, and at least the second terminal portion 62 connected to the thermistor 20 can use a bolt terminal type.

[0080] In addition, the structure of the thermistor 20 can be provided in a form that allows for easy assembly and disassembly of the second terminal portion 62.

[0081] Specifically, a pair of U-shaped terminal portions 23 protrude from the printed circuit board 21, enabling them to engage with the terminals of the second terminal portion 62 of the external terminal portion 60.

[0082] A thermistor chip 22 is mounted on the printed circuit board 21, and the thermistor chip 22 and the U-shaped terminal portion 23 are electrically connected to each other through printed lines 24.

[0083] With this structure, the thermistor 20 can be easily installed or removed from the second terminal 62, and can be easily replaced or maintained as needed.

[0084] In this invention, although the illustration shows the thermistor 20, which is provided with a U-shaped terminal portion 23, connected to the second terminal portion 62 of the external terminal portion 60, Figure 2 In its configuration, it can also be used in conjunction with reference contact 32.

[0085] Signal line connection terminals 63 are respectively provided in the first terminal portion 61 and the second terminal portion 62 of the external terminal portion 60. The signal line connection terminals 63 are connected to the first signal line 35 for detecting the electromotive force of the thermocouple 10 and the second signal line 36 for detecting the electromotive force of the thermistor 20.

[0086] As described above, the present invention can use a multi-channel analog-to-digital converter to convert the temperature detection results of thermocouple 10 and thermistor 20 into digital signals, so that thermocouple detection and cold junction compensation can be performed even without using a digital temperature sensor.

[0087] In addition, the external terminal section 60 can be used to perform more accurate cold junction compensation and prevent temperature deviation, thus having the feature of being able to perform cold junction compensation without preheating.

[0088] Although embodiments of the invention have been described above, these are merely examples, and those skilled in the art will understand that various modifications and equivalent embodiments are possible. Therefore, the true scope of protection of this invention should be determined by the following claims.

[0089] Industrial availability

[0090] This invention relates to a technique that utilizes natural laws to prevent errors in the cold junction compensation of thermocouples, and has industrial applicability.

Claims

1. A multi-channel thermocouple measuring device, wherein, include: Thermocouple and thermistor pair; The analog signal of the thermocouple and thermistor pair is input to the terminal section; as well as The detection unit, housed within a housing to isolate it from the outside, includes a multi-channel analog-to-digital converter that converts the analog signals of the thermocouple and thermistor pair input through the terminal section into digital signals. The terminal portion is an external terminal portion located outside the detection portion; The thermistor includes: A printed circuit board with a thermistor chip mounted on it; A pair of U-shaped terminals protrude from the printed circuit board; and The printed circuitry electrically connects each of the U-shaped terminals to the thermistor chip. The external terminal portion includes: The first terminal portion is connected to the thermocouple; and The second terminal portion is detachably connected to the U-shaped terminal.

2. The multi-channel thermocouple measuring device according to claim 1, wherein, It also includes a compensation unit that receives the digital signal from the detection unit and performs cold junction compensation.

3. The multi-channel thermocouple measuring device according to claim 1 or 2, characterized in that, The detection unit is configured to be multiple. Each of the aforementioned detection components is housed in a separate housing.

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