GB2562505A

GB2562505A - Thermocouple arrangement and method for measuring temperatures

Info

Publication number: GB2562505A
Application number: GB1707897.3A
Authority: GB
Inventors: Gajdarus Tomás
Original assignee: Continental Automotive GmbH
Current assignee: Continental Automotive GmbH
Priority date: 2017-05-17
Filing date: 2017-05-17
Publication date: 2018-11-21
Also published as: GB201707897D0

Abstract

A thermocouple arrangement 10 is disclosed for measuring a first temperature T2. The thermocouple arrangement 10 comprises a first thermocouple 20 including a first thermoelement 22 and a second thermoelement 24 coupled to the first thermoelement 22 at a first junction 26 configured to be arranged at the first temperature T2. The first and second thermoelements 22, 24 are made of different materials. The thermocouple arrangement 10 further comprises a second thermocouple 30 including a third thermoelement 32 and a fourth thermoelement 34 coupled to the third thermoelement 32 at a second junction 36. The third and fourth thermoelements 32, 34 are made of different materials. The thermocouple arrangement 10 further comprises a fifth thermoelement 52 connected to the second thermoelement 24 and being made of a fifth material different to the materials of the third and fourth thermoelements 32, 34. At least two voltage differences are measured of a first voltage difference V1 between the third thermoelement 32 and the fourth thermoelement 34, indicative of a temperature difference T1-T0, a second voltage difference V2 between the fourth thermoelement 34 and the fifth thermoelement 52, indicative of a temperature difference T2-T1 and a third voltage difference V3 between the third thermoelement 32 and the fifth thermoelement 52 indicative of a temperature difference T2-T1. The first temperature T2 is determined based at least partially on the at least two measured voltage differences V1, V2, V3. The thermocouple arrangement is suitable for measuring high temperatures, such as in vehicle exhaust gas systems. T2 may be at a high temperature, T1 a medium / high transition temperature and T0 may correspond to ambient temperature.

Description

(74) Agent and/or Address for Service:

Continental Automotive GmbH

PO BOX 22 16 39, 80506 Munich, Germany (54) Title of the Invention: Thermocouple arrangement and method for measuring temperatures Abstract Title: Thermocouple arrangement and method for measuring temperatures (57) A thermocouple arrangement 10 is disclosed for measuring a first temperature T2, The thermocouple arrangement 10 comprises a first thermocouple 20 including a first thermoelement 22 and a second thermoelement 24 coupled to the first thermoelement 22 at a first junction 26 configured to be arranged at the first temperature T2. The first and second thermoelements 22, 24 are made of different materials. The thermocouple arrangement 10 further comprises a second thermocouple 30 including a third thermoelement 32 and a fourth thermoelement 34 coupled to the third thermoelement 32 at a second junction 36. The third and fourth thermoelements 32, 34 are made of different materials. The thermocouple arrangement 10 further comprises a fifth thermoelement 52 connected to the second thermoelement 24 and being made of a fifth material different to the materials of the third and fourth thermoelements 32, 34. At least two voltage differences are measured of a first voltage difference V1 between the third thermoelement 32 and the fourth thermoelement 34, indicative of a temperature difference T1-TO, a second voltage difference V2 between the fourth thermoelement 34 and the fifth thermoelement 52, indicative of a temperature difference T2-T1 and a third voltage difference V3 between the third thermoelement 32 and the fifth thermoelement 52 indicative of a temperature difference T2-T1. The first temperature T2 is determined based at least partially on the at least two measured voltage differences V1, V2, V3. The thermocouple arrangement is suitable for measuring high temperatures, such as in vehicle exhaust gas systems. T2 may be at a high temperature, T1 a medium / high transition temperature and TO may correspond to ambient temperature.

1/1

Description

Thermocouple arrangement and method for measuring temperatures

The present invention relates to a thermocouple arrangement and a method for measuring temperatures. More particularly, the present invention relates to a thermocouple arrangement capable of measuring high temperatures, especially in automotive applications, such as in exhaust gas systems of vehicles, and to a method for measuring exhaust gas temperatures.

Noble metal thermocouples, such as Type-R (Pt-13% Rh vs. Pt) and Type-S (Pt-10%Rhvs. Pt) thermocouples, among others, may be used for measuring hot gas temperatures in excess of, for instance, 1800°C. For turbine applications, thermocouple probes typically are on the order of 10 cm 30 cm in length. Noble metal extension wires, thermoelectrically matched or compensating type to the thermoelements of such a thermocouple, may be used to bridge a distance between a distal end of the thermocouple and electrical circuitry configured to receive and process its output. The circuit extension may also include terminal connections to facilitate probe installation and maintenance.

Under certain conditions, it may become necessary to have very long extension wires. This may happen, for example, where the geometry and physical constraints of the object producing the hot gases to be measured, and the location within the object where these hot gases are accessible, are such that the electrical circuitry cannot be placed nearby. For noble metal thermocouples, the extension wires and terminal components may not be commercially available or cost prohibitive for the reguired length.

US 7 175 343 B2 discloses a multi-element thermocouple including two temperature measuring junctions.

GB 1 252 754 A relates to a thermoelectric device.

Further thermoelectric devices are known from, for example,

US 2016/0349117 Al, US 5 038 303, US 8 602 643 B2 and

WO 2009/053815 Al.

It is an object of the present invention to provide a thermocouple arrangement which is capable of reliably measuring a desired temperature and which is more cost efficient.

This object may be achieved by the thermocouple arrangement according to claim 1 and the method according to claim 10. Preferred embodiments are given in the dependent claims.

In a first aspect, a thermocouple arrangement for measuring a first temperature of, for example, an exhaust gas passing through an exhaust gas system of an internal combustion engine, is disclosed. The thermocouple arrangement comprises a first thermocouple including a first thermoelement and a second thermoelement coupled (or joined) to the first thermoelement at a first junction (or meeting at the first junction). The first junction is configured to be arranged at a first portion having a first temperature. The first thermoelement is made of a first material, and the second thermoelement is made of a second material different to the first material. The thermocouple arrangement further comprises a second thermocouple including a third thermoelement and a fourth thermoelement coupled (or joined) to the third thermoelement at a second junction (or meeting at the second junction) connected to the first thermoelement. The second junction is configured to be arranged at a second portion having a second temperature. The third thermoelement is made of a third material, and the fourth thermoelement is made of a fourth material different to the third material. The thermocouple arrangement further comprises a fifth thermoelement connected to the second thermoelement and being made of a fifth material different to the third material and the fourth material.

In a further aspect, a method for measuring a first temperature of, for example, an exhaust gas passing through an exhaust gas system of an internal combustion engine, is disclosed. The method comprises providing a thermocouple arrangement including a first thermocouple. The first thermocouple has a first thermoelement and a second thermoelement coupled (or joined) to the first thermoelement at a first junction (or meeting at the first junction). The first junction is configured to be arranged at a first portion having a first temperature . The first thermoelement is made of a first material, and the second thermoelement is made of a second material different to the first material. The thermocouple arrangement further includes a second thermocouple having a third thermoelement and a fourth thermoelement coupled (or joined) to the third thermoelement at a second junction (or meeting at the second junction) connected to the first thermoelement. The second junction is configured to be arranged at a second portion having a second temperature. The third thermoelement is made of a third material, and the fourth thermoelement is made of a fourth material different to the third material. The thermocouple arrangement further includes a fifth thermoelement connected to the second thermoelement and being made of a fifth material different to the third material and the fourth material. The method further comprises measuring at least two voltage differences of a first voltage difference between the third and fourth thermoelements, a second voltage difference between the fourth and fifth thermoelements and a third voltage difference between the third and fifth thermoelements, and determining the first temperature at the first junction based at least partially on the at least two measured voltage differences.

According to the present disclosure, it is described that the third and fourth thermoelements form the second thermocouple. However, it should be noted that, in view of analyzing the signals of the plurality of thermoelements, each of the third through fifth thermoelements may form a thermocouple with another one of the third through fifth thermoelements. For instance, the third thermoelement indirectly coupled to the fifth thermoelement via the first and second thermoelements may form a second thermocouple. Hence, for forming a thermocouple according to the present disclosure, there may be direct or indirect connections between two thermoelements forming said thermocouple. Further, two thermoelements coupled or joined to one another at or meeting at a junction may form a thermocouple.

In a preferred embodiment, the third material and/or the fourth material and/or the fifth material are different to the first material and/or the second material.

In a further preferred embodiment, the fifth thermoelement is the same length as the third thermoelement and/or the fourth thermoelement.

Advantageously, the first thermocouple is a type-N thermocouple, and the second thermocouple is a type-T or a type-J thermocouple.

It may be advantageous when distal ends of the third, fourth and fifth thermoelements that are opposite to the second junction and the connection to the second thermoelement, respectively, are configured to be arranged at a third portion having a third temperature. In such embodiment, the distal ends of the third, fourth and fifth thermoelements may be connected to first, second and third electrical terminals, respectively. Further, it is preferred that the first temperature can be estimated by at least two voltage differences of a first voltage difference between the first and second electrical terminals, a second voltage difference between the second and third electrical terminals and a third voltage difference between the first and third electrical terminals .

In a further preferred embodiment, the thermocouple arrangement may further comprise a mating assembly configured to at least partially receive and/or support the first through fifths thermoelements. Preferably, the mating assembly includes an electrically non-conductive plug through which the third thermoelement, the fourth thermoelement and the fifth thermoelement pass.

Further features and aspects of the present invention will become apparent by studying and executing the present disclosure and by consideration of appended Fig. 1 showing a thermocouple arrangement according to the present invention.

FIG. 1 shows a thermocouple arrangement 10 in accordance with the present invention. The thermocouple arrangement 10 corresponds to a thermocouple assembly comprising a first thermocouple 20 and a second thermocouple 30. The first thermocouple 20 and the second thermocouple 30 each share components with one another.

The first thermocouple 20 is a primary thermocouple including a first thermoelement 22 and a second thermoelement 24 . Preferably, the first thermoelement 22 and/or the second thermoelement 24 each are formed of a noble metal or a noble alloy. For example, the first thermoelement 22 (negative voltage) may be made of a first material, such as, for instance, a Nickel-Silicium (Nisi) alloy. The second thermoelement 24 (positive voltage) may be made of a second material different to the first material, such as, for instance, a Nickel-Chromium-Silicium (NiCrSi) alloy.

Thus, the first thermocouple 20 is preferably constituted by an

off-the-shelf	Type-N	thermocouple	probe .	In	alternative	em-
bodiments, the	first	thermocouple	2 0 may	be	constituted	by an
off-the-shelf	Type-R	thermocouple	probe .	In	yet alternative

embodiments, the first and second thermoelements 22, 24 belong to a non-letter designated thermocouple. An example of this may be to have the first thermoelement 22 formed of platinum and the second thermoelement 24 formed of palladium. In yet another embodiment, the first and second thermoelements are at least partially deposited on, and/or at least partially supported by, a thermally conductive and electrically non-conductive substrate .

The first and second thermoelements 22, 24 preferably are less than 30 cm in length. More preferably, the first and second thermoelements 22, 24 are less than 20 cm in length.

The first thermoelement 22 includes a first proximal end 22A and a first distal end 22B opposite to the first proximal end 22A. The second thermoelement 24 includes a second proximal end 24A and a second distal end 24B opposite to the second proximal end 24A. The first proximal end 22A and the second proximal end 24A are connected to one another at a first junction 26. Preferably, the first junction 26 is arranged at a first portion 2 having a first temperature T2. The first portion 2 may be, for example, a portion of an exhaust gas duct through which exhaust gas of an internal combustion engine (not shown) passes. With the thermocouple arrangement 10 of Fig. 1, during use, the temperature T2 of the exhaust gas is to be determined. The first temperature T2 may be a high temperature, for example, up to 2100°C.

The distal ends 22B, 24B of the first and second thermoelements 22, 24, respectively, are spaced from one another and, pref erably, are both at a second portion 4 having a second temperature T1.

The second thermocouple 30 is an auxiliary thermocouple including a third thermoelement 32 and a fourth thermoelement 34. Preferably, the third thermoelement 32 and/or the fourth thermoelement 34 each are formed of a base metal or a base alloy. For example, the third thermoelement 32 (positive) may be made of a third material, such as, for instance, a Copper-Nickel (CuNi) alloy.

The fourth thermoelement 34 (negative) may be made of a fourth material different to the third material, such as, for instance, a Nickel (Ni) alloy.

Thus, it is noted that neither the third nor fourth thermoelements 32, 34 is formed of the same material as the first thermoelement

22. Preferably, too, neither the third nor fourth thermoelements 32, 34 is formed of the same material as the second thermoelement

24. For example, the second thermocouple 30 is constituted by a Type-J or Type-T thermocouple.

The third thermoelement 32 includes a third proximal end 32A and a third distal end 32B opposite to the third proximal end 32A.

The fourth thermoelement 34 includes a fourth proximal end 34A and a fourth distal end 34B opposite to the fourth proximal end 34A. The third proximal end 32A and the fourth proximal end 34A are connected to one another at a second junction 36. Preferably, the second junction 36 is arranged at the second portion 4 having the second temperature Tl. The second temperature T1 may be a medium or high temperature, for example, a temperature between about 150°C and about 800°C.

The distal ends 32B, 34B of the third and fourth thermoelements 32, 34, respectively, are connected to first and second electrical terminals 42, 44, respectively. The electrical terminals

42, 44 are spaced apart from one another and both preferably are positioned at a third portion 6 having a known third (reference) temperature TO. More preferably, the first and second electrical terminals 42, 44 may be each part of a control unit 40 . The control unit 40 including, for example, an A/D converter is configured to receive any signals in the form of electric voltage from the thermocouple arrangement 10 and to calculate and/or estimate the first temperature T2 .

During operation, the first and second electrical terminals 42, 44 define between them a first voltage difference VI indicative of a temperature difference (T1 - TO) between the second temperature T1 and the third temperature TO. Therefore, the second thermocouple 30 is configured to provide information for determining the second temperature (which can be also referred to as a transition temperature) Tl, provided that the third temperature (which may be also referred to as a reference temperature) TO is known, from the following equation:

VI = S₃₄ (Tl - TO) wherein S34 is the mean relative Seebeck coefficient of the materials 3 and 4 between temperatures TO and Tl, which in this instance correspond to the third thermoelement 32 and the fourth thermoelement 34, respectively.

For instance, the third temperature TO may be measured by a separate temperature sensor, such as a known NTC temperature sensor. The third temperature TO may substantially correspond to ambient temperature.

The thermocouple arrangement 10 also includes a fifth thermoelement 52 hat has preferably the same length as the third thermoelement 32 and the fourth thermoelement 34. The fifth thermoelement 52 is formed of a fifth material that is different from the material of the second thermoelement 24. The fifth thermoelement 52 has a proximal end 52A that is connected to the distal end 24B of the second thermoelement 24 at third junction 56, and a distal end 52B that is connected to a third electrical terminal 46. The third terminal 46 is preferably also part of the control unit 40.

During operation, the second electrical terminal 44 and the third electrical terminal 46 define between them a second voltage difference V2 indicative of a temperature difference (T2 - Tl) between the first temperature T2 and the second temperature Tl. Therefore, the first thermocouple 20 is configured to provide information that helps to determine the relevant first temperature T2 according to the following equation:

K2 = S₁₂ (T2 - Tl) + S₄₅ (Tl - TO) wherein S12 is the mean relative Seebeck coefficient of the materials 1 and 2 between temperatures Tl and T2, which in this instance correspond to the first thermoelement 22 and second thermoelement 24, respectively, and S45 is the mean relative Seebeck coefficient of the materials 4 and 5 between temperatures TO and Tl, which in this instance correspond to the fourth thermoelement 34 and the fifth thermoelement 52, respectively .

With the above equation, applying an appropriate transformation, the first temperature T2 may be calculated by:

V2 - S₄₅ (Tl - TO)

T2 = Tl + -----------612

In addition, during operation, the first electrical terminal 42 and the third electrical terminal 46 define between them a third voltage difference V3 indicative of a temperature difference (T2 - Tl) between the first temperature T2 and the second temperature Tl. Therefore, the first thermocouple 20 is configured to provide information that helps to determine the relevant first temperature T2 according to the following equation:

V3 = S₁₂ (T2 - Tl) + S₃₅ (Tl - TO) wherein S12 is the mean relative Seebeck coefficient of the materials 1 and 2 between temperatures Tl and T2, which in this instance correspond to the first thermoelement 22 and second thermoelement 24, respectively, and S35 is the mean relative Seebeck coefficient of the materials 3 and 5 between temperatures TO and Tl, which in this instance correspond to the third thermoelement 32 and the fifth thermoelement 52, respectively .

V3 - S₃₅ (Tl - TO)

T2 = Tl + ------—------^12

Generally, with the thermocouple arrangement 10 of Fig. 1, by measuring two voltage differences VI, V2, V3 of the first voltage difference VI, the second voltage difference V2 and the third voltage difference V3, the other of the two voltage differences may be calculated and, hence, the first temperature T2 may be calculated. For example, the voltage differences VI, V2, V3 follow the following equation:

VI + V2 = V3

As the materials of the fourth thermoelement 34 and the fifth thermoelement 52 are different to the materials of the first and second thermoelements 22, 24, the second voltage difference V2 is unequal to zero, provided that the first temperature T2 is equal to the second temperature Tl. In contrast, when using two wires made of the same material, the voltage difference may be merely transferred. Such a wiring using different materials for the third through fifth thermoelements 32, 34, 52 may be configured in a way to have higher voltageat the output when having normal engine operating condition, in particular, when T2 > Tl > TO, compared to a situation where the fourth and fifth thermoelements 34, 52 are made of the same material. However, more postprocessing may be needed within, for example, the control unit 40.

In actual practice, the calculation is more complicated than described above, since the relative Seebeck coefficient is a function of temperature. However, constructing a thermocouple arrangement with standard thermocouple materials, such as described in ASTM E230, allows one to use industry accepted E(T) equations and related tolerances.

Thus, upon detecting the first, second and/or third voltage differences VI, V2, V3, established equations and/or tables may be used to calculate and/or interpolate, as needed, to estimate the first and second temperatures T2 and Tl, respectively.

As seen in Fig. 1, the third thermoelement 32 and the fourth thermoelement 34 belong to a first voltage difference subcircuit which produces the first voltage difference VI. Similarly, the first thermoelement 22, the second thermoelement 24, the fourth thermoelement 34 and the fifth thermoelement 52 belong to a second voltage difference subcircuit which produces the second voltage difference V2 . Similarly, the first thermoelement 22, the second thermoelement 24, the third thermoelement 32 and the fifth thermoelement 52 belong to a third voltage difference subcircuit which produces the third voltage difference V3 . The distal ends 32B, 34B, 52B of the third, fourth and fifth thermoelements 32, 34, 52, respectively, are sufficiently electrically isolated from one another to allow measurement of the first open circuit voltage difference VI between the third thermoelement 32 and the fourth thermoelement 34, allow measurement of the second open circuit voltage difference V2 between the fourth thermoelement 34 and the fifth thermoelement 52 and allow measurement of the third open circuit voltage difference V3 between the third thermoelement 32 and the fifth thermoelement 52.

Significantly, each of the third to fifth thermoelements 32, 34, 52 is common to two voltage difference subcircuits. In particular, the fourth thermoelement 34 is common to the first and second voltage difference subcircuits, the third thermoelement 32 is common to the first and third voltage difference subcircuits, and the fifth thermoelement 52 is common to the second and third voltage difference subcircuits. The third, fourth and fifth thermoelements 32, 34, 52 preferably comprise conductors, such as 20 AWG wire, individually insulated and bundled together as a multi-wire flexible cable extending between their proximal ends 32A, 34A, 52A and their distal ends 32B, 34B, 52B, respectively .

The lengths of the third, fourth and fifth thermoelements 32, 34, 52, which effectively serve as extension wires, preferably are anywhere from less than 20 cm to several meters. The resulting thermocouple arrangement 10 is suitable for measuring a high, unknown first temperature T2 by making two voltage measurements, using the first thermocouple 20 that is cascaded, via its first thermoelement 22, with the second thermocouple 30 configured to measure the second (transition) temperature Tl.

By using an appropriate calibration process, the present invention may be applied to any thermocouple arrangement having a structure as shown in Fig. 1 with the third through fifth thermoelements 32, 34, 52 being made of different materials. The thermocouple arrangement 10 may be used to measure temperatures with the first thermocouple 20 proximate to the hostile environment, and the second (auxiliary) thermocouple 30 extending from a leg of the first (primary) thermocouple 20 to a remote location where the electrical connectors 42, 44, 46 are positioned. This allows for using readily available base metal extension wires and connectors (second thermocouple 30 and fifth thermoelement 52), which provides cost advantages when using a noble metal first (primary) thermocouple 20. Such base metal extensions may also allow for using non-letter designated noble metal first thermocouples in situations where matched lead wires and connectors are not available.

In a preferred embodiment, as shown in Fig. 1, the second junction 36 and the third junction 56, where the second thermoelement 24 and the fifth thermoelement 52 are coupled or jointed to one another, preferably are both at the same temperature, namely at the second temperature Tl. In one embodiment, the second and third junctions 36, 56 simply may be positioned close to one another to help ensure that the same (transition) temperature Tl is experienced. In another embodiment, in addition to simply being proximate to one another, a mating assembly 60 is provided that supports portions of one at least one of the first through fifth thermoelements 22, 24, 32, 34, 52. More preferably, the mating assembly 60 is such that the second and third junctions 36, 56 are electrically isolated from one another, yet are still in thermal communication with each other so that they are able to experience a common temperature Tl. The mating assembly 60 may preferably include an electrically non-conductive plug through which the third thermoelement 32, the fourth thermoelement 34 and the fifth thermoelement 52 pass.

The electrical terminals 42, 44, 46, at which the distal ends 32B, 34B, 52B of the third, fourth and fifth thermoelements 32, 34, 52, respectively, terminate, preferably are all at a same, and known, third (reference) temperature TO that may be measured by a separate temperature sensor (not shown), such as, for example, a NTC temperature sensor.

In one embodiment, the electrical terminals 42, 44, 46 are mounted on a termination strip 48 which may be also part of the control unit 40. The temperature of the termination strip 48 may be temperature controlled to maintain the termination strip 48 at the predetermined reference temperature TO. Alternatively, or in addition, an auxiliary thermometer may be used to gauge the temperature at the terminals 42, 44, 46, and the output of this thermometer is used as the reference temperature TO in the equations above to determine the first temperature T2 at the first junction 26.

During use, the electrical terminals 42, 44, 46 provide the first second and third voltage differences VI, V2, V3 to additional electrical circuitry which may be part of the control unit 40, known to those skilled in the art. This additional circuitry may, among other things, sense the first, second and third voltage differences VI, V2, V3 and convert it into analog and/or digital signals, at least one of which preferably carries information that is proportional to the first temperature T2 for further processing. Thus, a processor associated with this circuitry may be configured to use at least two voltage differences of the first to third voltage differences VI, V2, V3 to determine the second temperature T1 and, from that, the first temperature T2 . The first temperature T2, which is then determined as a function of time, may then be used to provide real-time control of the equipment creating that temperature, such as, for instance, an internal combustion engine used in combination with a vehicle, such as, for example, an automobile, a commercial vehicle, a truck, a farming vehicle, etc.

With the thermocouple arrangement 10 of the present invention, there may be no zero voltage difference of the first, second and third voltage differences VI, V2, V3. Therefore, assuming that the second junction 36 and the third junction 56 are provided within a fixation tube (not shown) of, for instance, a mineral insulated cable (MIC) , if there is a short to ground, the location of said short may be identified. To the contrary, regarding an arrangement where a zero voltage difference may appear due to the fourth and fifth thermoelement 34, 52 being made of the same material, if there is a short to ground, the location of said short may not be identified.

Although not shown in Fig. 1, the thermocouple arrangement 10 may be insulated from ground, such as, for example, the ground of the vehicle. However there may arise several situations in the reality which may lead to an insulation resistance drop between the thermocouple arrangement 10 and the ground, such as, for example, due to water intrusion and/or mechanical damage of the wires. The present invention may provide a clear detection system when short to ground may be caused by water intrusion to the second portion 4 or into the mating assembly 60. With the circuitry according to Fig. 1 and, when short to ground may be measured by the control unit 40 and the thermocouples are showing the same temperature (i.e. thermocouple 30 and the thermocouple formed by the thermoelement 52 and one of the thermoelelements 32, 34) , it may be determined that a water intrusion into the second portion or into the mating assembly 60 (or a so-called fixation tube) occurred. To the contrary, when using thermoelements where two thermoelements are made of the same material, said detection of water intrusion may not be made, as the thermoelements made of the same material may provide a zero voltage difference in the temperature gradient.

A particular embodiment of the present invention is specifically illustrated and/or described herein. However, it will be ap10 predated that modifications and variations of the present invention are covered by the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.

Claims

1. A thermocouple arrangement (10) for measuring a first temperature (T2) of, for example, an exhaust gas passing through an exhaust gas system of an internal combustion engine, the thermocouple arrangement (10) comprising:

a first thermocouple (20) including a first thermoelement (22) and a second thermoelement (24) coupled to the first thermoelement (22) at a first junction (26), the first junction (26) being configured to be arranged at a first portion (2) having a first temperature (T2), the first thermoelement (22) being made of a first material, the second thermoelement (24) being made of a second material different to the first material;

a second thermocouple (30) including a third thermoelement (32) and a fourth thermoelement (34) coupled to the third thermoelement (32) at a second junction (36) connected to the first thermoelement (22), the second junction (36) being configured to be arranged at a second portion (4) having a second temperature (Tl), the third thermoelement (32) being made of a third material, the fourth thermoelement (34) being made of a fourth material different to the third material; and a fifth thermoelement (52) connected to the second thermoelement (24) and being made of a fifth material different to the third material and the fourth material.

2. The thermocouple arrangement (10) of claim 1, wherein the third material and/or the fourth material and/or the fifth material are different to the first material and/or the second material.

3. The thermocouple arrangement (10) of any one of the preceding claims, wherein the fifth thermoelement (52) is the same length as the third thermoelement (32) and/or the fourth thermoelement (34).

4. The thermocouple arrangement (10) of any one of the preceding claims, wherein the first thermocouple (20) is a type-N thermocouple, and the second thermocouple (30) is a type-T or a type-J thermocouple .

5. The thermocouple arrangement (10) of any one of the preceding claims, wherein distal ends (32B, 34B, 52B) of the third, fourth and fifth thermoelements (32, 34, 52) that are opposite to the second junction (36) and the connection to the second thermoelement (24), respectively, are configured to be arranged at a third portion (6) having a third temperature (TO).

6. The thermocouple arrangement (10) of claim 5, wherein the distal ends (32A, 34B, 52B) of the third, fourth and fifth thermoelements (32, 34, 52) are connected to first, second and third electrical terminals (42, 44, 46), respectively.

7. The thermocouple arrangement (10) of claim 6, wherein the first temperature (T2) can be estimated based at least partially on at least two voltage differences of a first voltage difference (VI) between the first and second electrical terminals (42, 44) , a second voltage difference (V2) between the second and third electrical terminals (44, 46) and a third voltage difference (V3) between the first and third electrical terminals (42, 46).

8. The thermocouple arrangement (10) of any one of the preceding claims, further comprising a mating assembly (60) configured to at least partially receive and/or support the first through fifths thermoelements (22, 24, 32, 34, 52).

9. The thermocouple arrangement (10) of claim 8, wherein the mating assembly (60) includes an electrically non-conductive plug through which the third thermoelement (32) , the fourth thermoelement (34) and the fifth thermoelement pass (52) .

10. A method for measuring a first temperature (T2) of, for example, an exhaust gas passing through an exhaust gas system of an internal combustion engine, the method comprising:

providing a thermocouple arrangement (10) including:

a first thermocouple (20) having a first thermoelement (22) and a second thermoelement (24) coupled to the first thermoelement (22) at a first junction (26), the first junction (26) being configured to be arranged at a first portion (2) having a first temperature (T2), the first thermoelement (22) being made of a first material, the second thermoelement (24) being made of a second material different to the first material;

a second thermocouple (30) having a third thermoelement (32) and a fourth thermoelement (34) coupled to the third thermoelement (32) at a second junction (36) connected to the first thermoelement (22), the second junction (36) being configured to be arranged at a second portion (4) having a second temperature (Tl), the third thermoelement (32) being made of a third material, the fourth thermoelement (34) being made of a fourth material different to the third material; and a fifth thermoelement (52) connected to the second thermoelement (24) and being made of a fifth material different to the third material and the fourth material;

measuring at least two voltage differences of a first voltage difference (VI) between the third thermoelement (32) and the fourth thermoelement (34), a second voltage difference (V2) between the fourth thermoelement (34) and the fifth thermoelement (52) and a third voltage difference (V3)

20 between the third thermoelement (32) and the fifth thermoelement (52); and determining the first temperature (T2) at the first junction (26) based at least partially on the at least two 5 measured voltage differences (VI, V2, V3).

Intellectual

Property Office

Application No: GB1707897.3