CA1085967A - Thermocouple probe - Google Patents
Thermocouple probeInfo
- Publication number
- CA1085967A CA1085967A CA292,514A CA292514A CA1085967A CA 1085967 A CA1085967 A CA 1085967A CA 292514 A CA292514 A CA 292514A CA 1085967 A CA1085967 A CA 1085967A
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- CA
- Canada
- Prior art keywords
- weight
- exceeding
- tube
- nickel
- tube member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/02—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples
- G01K7/04—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples the object to be measured not forming one of the thermoelectric materials
- G01K7/06—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples the object to be measured not forming one of the thermoelectric materials the thermoelectric materials being arranged one within the other with the junction at one end exposed to the object, e.g. sheathed type
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention provides a thermocouple probe comprising: a tube member having a closed end and an open end and made of a nickel-based alloy containing from 5 to 25% by weight chromium and one or more of: (a) rare earth element in an amount not exceeding 1% by weight; (b) aluminium in an amount not exceeding 5% by weight; and (c) one or more of the elements silicon, zirconium, titanium and niobium, provided that each element does not exceed 1% by weight; the balance being nickel;
a wire member disposed in and axially extending through said tube member and having one end welded to an inner wall of said closed end of said tube member, said wire member being made of a nickel-based alloy containing one or more of: (d) aluminium in an amount not exceeding 7% by weight; (e) silicon in an amount not exceeding 7% by weight, provided that the sum of aluminium and silicon does not exceed 10% by weight; (f) rare earth element in an amount not exceeding 1% by weight; and (g) one or more of the elements carbon, cobalt, manganese and iron, provided that the sum of these elements does not exceed 1% by weight; the balance being nickel; and an electrically insulating material filling said tube member so as to support said wire member substantially immovably in said tube member.
The thermocouple has a good responsiveness and high durability in use.
The present invention provides a thermocouple probe comprising: a tube member having a closed end and an open end and made of a nickel-based alloy containing from 5 to 25% by weight chromium and one or more of: (a) rare earth element in an amount not exceeding 1% by weight; (b) aluminium in an amount not exceeding 5% by weight; and (c) one or more of the elements silicon, zirconium, titanium and niobium, provided that each element does not exceed 1% by weight; the balance being nickel;
a wire member disposed in and axially extending through said tube member and having one end welded to an inner wall of said closed end of said tube member, said wire member being made of a nickel-based alloy containing one or more of: (d) aluminium in an amount not exceeding 7% by weight; (e) silicon in an amount not exceeding 7% by weight, provided that the sum of aluminium and silicon does not exceed 10% by weight; (f) rare earth element in an amount not exceeding 1% by weight; and (g) one or more of the elements carbon, cobalt, manganese and iron, provided that the sum of these elements does not exceed 1% by weight; the balance being nickel; and an electrically insulating material filling said tube member so as to support said wire member substantially immovably in said tube member.
The thermocouple has a good responsiveness and high durability in use.
Description
108596q The present invention relates in general to a temperature sensing device and more particularly to a thermo-couple probe which is suitable for measuring the temperature of the exhaust gases issuing from an automotive internal combustion engine.
Modern automotive internal combustion engines are equipped at their exhaust systems with exhaust gas purifying devices, such as a catalytic converter and a thermal reactor, for converting the harmful compounds such as HC, CO and NOx in the exhaust gases into harmless compounds such as H2O, CO2 and N2.
In order to operate these gas purifying devices at their optimum efficiency it is necessary to check or monitor the temper-atures of the exhaust gases passing through these devices by placing temperature sensors in the devices. In most cases, however, such temperature sensors are located in positions where high temperature, severe vibration, exposure to water splashes, and stone impingement very often occur. Thus, in practical use, not only the positioning of these temperature sensors in the purifying devices but also the assemblage of the same must -be carefully done by taking the above-mentioned facts into consideration.
Hitherto, two types of temperature sensors have been widely used in the above-mentioned field, one of which 1~8596~7 is a thermistor type sensor comprising a semi-conductor in ceramic form, and the other of which is a thermo-couple type sensor comprising two dissimilar metal wires connected or welded at their one ends to form a so-called hot or measuring junction, a protection metal tube enclosing the two metal wires, insulating material packed in the tube for insulation between the wires and the tube.
In the thermistor type sensor, however, the temperature sensing section thereof is relatively large and thus has a large thermal capacity, thus its responsiveness is relatively poor. ~ -Furthermore, because of the relatively early aging of the contacting section of the thermistor proper with electrodes, the life time of this type of sensor is relatively short.
In the thermocouple type sensor, the above-mentioned troubles encountered in the thermist~r type sensor are solved to some extent. However, its responsiveness has not satisfied the request in sensing the temperature sufficiently.
Therefore, it is an object of the present invention to provide an improved thermocouple temperature sensor which has improved responsiveness and high durability in use.
.
,, ~ , .......................... :
' , -- .. :: ~ ' :' , ~08596q It is another object of the present invention to provide a thermocouple probe which can be used to measure the temperature of the exhaust gases issued from the internal combustion engine.
It is a further object of the present invention to provide a thermocouple probe the measuring junction of which can be arranged to directly contact the medium, the temperature of which is to be measured, the thermocouple probe is thus extremely responsive.
It is a still further object of the present invention to provide a thermocouple probe in which one of the dissimilar thermoelectric metals which form the measuring junction acts as a so-called protection tube, so that the probe is simple in construction and easily assembled, and accordingly economical.
It is a still further object of the present invention to provide a thermocouple probe in which one of the dissimilar thermoelectric metals, exhibiting higher corrosion resistance than the other, is formed into a tube directly exposed to the measured medium.
According to the present invention, there is provided a thermocouple probe comprising: a tube member having a closed end and an open end and made of a nickel-based alloy containing from 5 to 25% by weight chromium and one or more of: (a) rare earth elementin an amount not exceeding 1~ by weight; (b) aluminium in an amount not exceeding 5% by weight; and (c) one or more of the elements silicon, zirconium, titanium and niobium, provided that each element does not exceed 1~ by weight; the balance being nickel; a wire member disposed in and axially extending through said tube member and having one end welded to an inner wall of said closed end of said tube member, said wire member being made of a nickel-based alloy containing one or more of:
(d) aluminium in an amount not exceeding 7% by weight; (e) : . .
~o8596~
silicon in an amount not exceeding 7% by weight, provided that the sum of aluminium and silicon does not exceed 10% by weight;
(f) rare earth element in an amount not exceeding 1% by weight;
and (g) one or more of the elements carbon, cobalt, manganese -and iron, provided that the sum of these elements does not exceed 1% by weight; the balance being nickel; and an electrically insulating material filling said tube member so as to support said wire member substantially immovably in said tube member.
Other objects and advantages of the present invention -10will become apparent from the following description when taken in conjunction with the accompanying drawings, in which~
Fig. 1 is a schematic sectional view of an exemplary prior art temperature sensing thermocouple probe;
Fig. 2 is a schematic sectional view of a first preferred embodiment of a thermocouple probe according to the present invention;
Fig. 3 is a schematic sectional view of a second preferred embodiment !, ' J,~I.
.. ~ , ' '~ , ' .
' ' .
108596~7 of a thermocouple probe according to the present invention;
Fig. 4 is a schematic sectional view of an apparatus incorporating the thermocouple probe shown in Fig. 2; and Fig. 5 is a sectional view taken along the line V-V
of Fig. 4.
Prior to describing the thermocouple probe according to the present invention, description of the prior art thermo-couple probe will be given with the aid of Fig. 1 in order to clarify the inventive features of the subject invention.
In Fig. 1 a conventional thermocouple probe is illustrated, comprising a protection metal tube 10 having a closed end 12 and an open end 14, a pair of dissimilar metal wires 16 and 18 spacedly disposed in the protection tube 10 and forming a hot or measuring junction 20 at one end thereof near the closed end of the protection tube, and an electrically insulating material 22, for example, magnesium oxide (MgO)filling the cavity of the protection tube 10 in order to electrically insulate the metal wires 16 and 18 from the protection tube.
However, in such a conventional sensing element, there arises a problem that the measuring junction 20 fails to reach a suitable temperature rapidly due to heat absorption --` 108S967 by the protection tube 2 and the filling insulating material 22, and therefore the responsiveness of the thermocouple probe is low. Of course, its responsiveness may be fairly improved by thinning the protection tube 10 as well as the metal wires 16.
However, this procedure will lower the mechanical strength of the thermocouple probe.
Thus, as has been described, the present invention contemplates to eliminate the drawbacks encountered in the above-mentioned conventional thermocouple probe.
Refexring now to Fig. 2, there is shown a thermocouple probe according to the present invention, which element comprises a metal tube 24 constructed of a thin thermoelectric metal and having a closed end 26 and an open end 28. Concentrically disposed in the tube 24 is a metal wire 30 made of another thermoelectric metal which has one end welded or brazed to an inner surface of the closed end 26 at a point 32 to form the measuring junction. The cavity of the tube 24 is packed or filled with an electrically insu~ating material 34 such as magne-sium oxide (MgO) for reliable insulation between the wire 30 and the tube 24. For security against breakage during assembly and durability in use of -, :
-: 108S96~7 the thermocouple probe, the thickness of the tube 24, indicated by a letter Tl in Fig. 2. and the thickness T2 of the insulating material 34 should each be at least 10% of the outer diameter of the tube. Furthermore, the diameter T3 of the wire should -be at least 20% of the outer diameter of the tube 24. Preferably, the section substantially constituting the measuring junction 32 is formed compact or small in size for allowing the junction 32 to have a high sensitivity to temperature to be measured.
An example for accomplishing this will be described hereinnext.
In Fig. 3, a second preferred embodiment of the thermocouple probe having more improved characteristics in responsiveness is illustrated, as comprising a metal tube 24' ~ -having a large diameter portion 24'a (for example 3.2mm~) and a small diameter portion 24'b (for example 1.6mm~) which are integrally connected via a conical portion 24'c. The metal tube 24' has at the small diameter portion 24'_ a closed end 26' and at the large diameter portion 24'a an open end 28'.
Concentrically disposed in the tube 24' is a metal wire 30' which has a small diameter portion 30'b welded or brazed to the closed end 26' of the tube 24' forming a measuring junction 32' and a large diameter portion 30'a concentrically located in the large diameter portion 24'a of the metal .
~0~1596!7 ~
: .
tube 24', as shown. The metal tube 24' and the metal wire 30', similar to the case of the first embodiment, are constructed of dissimilar thermoelectric metals, respectively. The cavity of the tube 24' is also filled with an electrically insulating material 34'. Preferably, the axial length L of the small diameter portion 24'b is made at least ten times as long as the outer diameter D of the same.
Now, it should be noted that corrosion resistance of the tube 24 or 24' is synergetically increased by the deposition of at least one heat insulating compound such as A12O3, Cr2O3, SiO2, TiO2, BeO, ~gO and ZrO2 on the outer surface of the tube.
According to the present invention, consideration on the materials for the tube 24 or 24' and the wire 30 or 30' is further required. Several experiments conducted by the inventors have revealed that the following alloys are very suitable for the construction of the tube and the wire:
Alloy for the tube 24 or 24'-- A nickel-base alloy consisting of 5 to 25% Cr, up to 1% rare earth element(s), up to 5~ Al, one or more of the elements Si, Zr, Ti and Nb, provided each does not exceed 1% and the balance of Ni;
Alloy for the wire 30 or 30'-- A nickel-base alloy ~ -, ': . ' ' '-108S96~
consisting of one or more of up to 7% Al, up to 7% Si, provided the sum of Al and Si does not exceed 10~, up to 1% rare earth element(s), up to 1~ sum of one or more of C, Co, Mn and Fe, and the balance of Ni.
Tables 1 and 2 show nickel-base alloys (C) to (K) and (O) to (R) which can be respectively used for the construction of the tube 24 or 24' and the wire 30 or 30'.
For the comparison, conventional alloys (A), (B) and (L) to (N) are shown in these tables. In Tables 3 and 4, there are `~
respectively shown the characteristics of the alloys (A) to tR), in which (1) indicates weight increase by oxidation, (2) thermo-electromotive force and (3) change in thermo-electromotive force by aging. These data were obtained under the following test conditions, in which:
(~) weight increase by oxidation Supplied gas: the atmosphere Temperature: 1100C
Operation hours: 50 hr.
Modern automotive internal combustion engines are equipped at their exhaust systems with exhaust gas purifying devices, such as a catalytic converter and a thermal reactor, for converting the harmful compounds such as HC, CO and NOx in the exhaust gases into harmless compounds such as H2O, CO2 and N2.
In order to operate these gas purifying devices at their optimum efficiency it is necessary to check or monitor the temper-atures of the exhaust gases passing through these devices by placing temperature sensors in the devices. In most cases, however, such temperature sensors are located in positions where high temperature, severe vibration, exposure to water splashes, and stone impingement very often occur. Thus, in practical use, not only the positioning of these temperature sensors in the purifying devices but also the assemblage of the same must -be carefully done by taking the above-mentioned facts into consideration.
Hitherto, two types of temperature sensors have been widely used in the above-mentioned field, one of which 1~8596~7 is a thermistor type sensor comprising a semi-conductor in ceramic form, and the other of which is a thermo-couple type sensor comprising two dissimilar metal wires connected or welded at their one ends to form a so-called hot or measuring junction, a protection metal tube enclosing the two metal wires, insulating material packed in the tube for insulation between the wires and the tube.
In the thermistor type sensor, however, the temperature sensing section thereof is relatively large and thus has a large thermal capacity, thus its responsiveness is relatively poor. ~ -Furthermore, because of the relatively early aging of the contacting section of the thermistor proper with electrodes, the life time of this type of sensor is relatively short.
In the thermocouple type sensor, the above-mentioned troubles encountered in the thermist~r type sensor are solved to some extent. However, its responsiveness has not satisfied the request in sensing the temperature sufficiently.
Therefore, it is an object of the present invention to provide an improved thermocouple temperature sensor which has improved responsiveness and high durability in use.
.
,, ~ , .......................... :
' , -- .. :: ~ ' :' , ~08596q It is another object of the present invention to provide a thermocouple probe which can be used to measure the temperature of the exhaust gases issued from the internal combustion engine.
It is a further object of the present invention to provide a thermocouple probe the measuring junction of which can be arranged to directly contact the medium, the temperature of which is to be measured, the thermocouple probe is thus extremely responsive.
It is a still further object of the present invention to provide a thermocouple probe in which one of the dissimilar thermoelectric metals which form the measuring junction acts as a so-called protection tube, so that the probe is simple in construction and easily assembled, and accordingly economical.
It is a still further object of the present invention to provide a thermocouple probe in which one of the dissimilar thermoelectric metals, exhibiting higher corrosion resistance than the other, is formed into a tube directly exposed to the measured medium.
According to the present invention, there is provided a thermocouple probe comprising: a tube member having a closed end and an open end and made of a nickel-based alloy containing from 5 to 25% by weight chromium and one or more of: (a) rare earth elementin an amount not exceeding 1~ by weight; (b) aluminium in an amount not exceeding 5% by weight; and (c) one or more of the elements silicon, zirconium, titanium and niobium, provided that each element does not exceed 1~ by weight; the balance being nickel; a wire member disposed in and axially extending through said tube member and having one end welded to an inner wall of said closed end of said tube member, said wire member being made of a nickel-based alloy containing one or more of:
(d) aluminium in an amount not exceeding 7% by weight; (e) : . .
~o8596~
silicon in an amount not exceeding 7% by weight, provided that the sum of aluminium and silicon does not exceed 10% by weight;
(f) rare earth element in an amount not exceeding 1% by weight;
and (g) one or more of the elements carbon, cobalt, manganese -and iron, provided that the sum of these elements does not exceed 1% by weight; the balance being nickel; and an electrically insulating material filling said tube member so as to support said wire member substantially immovably in said tube member.
Other objects and advantages of the present invention -10will become apparent from the following description when taken in conjunction with the accompanying drawings, in which~
Fig. 1 is a schematic sectional view of an exemplary prior art temperature sensing thermocouple probe;
Fig. 2 is a schematic sectional view of a first preferred embodiment of a thermocouple probe according to the present invention;
Fig. 3 is a schematic sectional view of a second preferred embodiment !, ' J,~I.
.. ~ , ' '~ , ' .
' ' .
108596~7 of a thermocouple probe according to the present invention;
Fig. 4 is a schematic sectional view of an apparatus incorporating the thermocouple probe shown in Fig. 2; and Fig. 5 is a sectional view taken along the line V-V
of Fig. 4.
Prior to describing the thermocouple probe according to the present invention, description of the prior art thermo-couple probe will be given with the aid of Fig. 1 in order to clarify the inventive features of the subject invention.
In Fig. 1 a conventional thermocouple probe is illustrated, comprising a protection metal tube 10 having a closed end 12 and an open end 14, a pair of dissimilar metal wires 16 and 18 spacedly disposed in the protection tube 10 and forming a hot or measuring junction 20 at one end thereof near the closed end of the protection tube, and an electrically insulating material 22, for example, magnesium oxide (MgO)filling the cavity of the protection tube 10 in order to electrically insulate the metal wires 16 and 18 from the protection tube.
However, in such a conventional sensing element, there arises a problem that the measuring junction 20 fails to reach a suitable temperature rapidly due to heat absorption --` 108S967 by the protection tube 2 and the filling insulating material 22, and therefore the responsiveness of the thermocouple probe is low. Of course, its responsiveness may be fairly improved by thinning the protection tube 10 as well as the metal wires 16.
However, this procedure will lower the mechanical strength of the thermocouple probe.
Thus, as has been described, the present invention contemplates to eliminate the drawbacks encountered in the above-mentioned conventional thermocouple probe.
Refexring now to Fig. 2, there is shown a thermocouple probe according to the present invention, which element comprises a metal tube 24 constructed of a thin thermoelectric metal and having a closed end 26 and an open end 28. Concentrically disposed in the tube 24 is a metal wire 30 made of another thermoelectric metal which has one end welded or brazed to an inner surface of the closed end 26 at a point 32 to form the measuring junction. The cavity of the tube 24 is packed or filled with an electrically insu~ating material 34 such as magne-sium oxide (MgO) for reliable insulation between the wire 30 and the tube 24. For security against breakage during assembly and durability in use of -, :
-: 108S96~7 the thermocouple probe, the thickness of the tube 24, indicated by a letter Tl in Fig. 2. and the thickness T2 of the insulating material 34 should each be at least 10% of the outer diameter of the tube. Furthermore, the diameter T3 of the wire should -be at least 20% of the outer diameter of the tube 24. Preferably, the section substantially constituting the measuring junction 32 is formed compact or small in size for allowing the junction 32 to have a high sensitivity to temperature to be measured.
An example for accomplishing this will be described hereinnext.
In Fig. 3, a second preferred embodiment of the thermocouple probe having more improved characteristics in responsiveness is illustrated, as comprising a metal tube 24' ~ -having a large diameter portion 24'a (for example 3.2mm~) and a small diameter portion 24'b (for example 1.6mm~) which are integrally connected via a conical portion 24'c. The metal tube 24' has at the small diameter portion 24'_ a closed end 26' and at the large diameter portion 24'a an open end 28'.
Concentrically disposed in the tube 24' is a metal wire 30' which has a small diameter portion 30'b welded or brazed to the closed end 26' of the tube 24' forming a measuring junction 32' and a large diameter portion 30'a concentrically located in the large diameter portion 24'a of the metal .
~0~1596!7 ~
: .
tube 24', as shown. The metal tube 24' and the metal wire 30', similar to the case of the first embodiment, are constructed of dissimilar thermoelectric metals, respectively. The cavity of the tube 24' is also filled with an electrically insulating material 34'. Preferably, the axial length L of the small diameter portion 24'b is made at least ten times as long as the outer diameter D of the same.
Now, it should be noted that corrosion resistance of the tube 24 or 24' is synergetically increased by the deposition of at least one heat insulating compound such as A12O3, Cr2O3, SiO2, TiO2, BeO, ~gO and ZrO2 on the outer surface of the tube.
According to the present invention, consideration on the materials for the tube 24 or 24' and the wire 30 or 30' is further required. Several experiments conducted by the inventors have revealed that the following alloys are very suitable for the construction of the tube and the wire:
Alloy for the tube 24 or 24'-- A nickel-base alloy consisting of 5 to 25% Cr, up to 1% rare earth element(s), up to 5~ Al, one or more of the elements Si, Zr, Ti and Nb, provided each does not exceed 1% and the balance of Ni;
Alloy for the wire 30 or 30'-- A nickel-base alloy ~ -, ': . ' ' '-108S96~
consisting of one or more of up to 7% Al, up to 7% Si, provided the sum of Al and Si does not exceed 10~, up to 1% rare earth element(s), up to 1~ sum of one or more of C, Co, Mn and Fe, and the balance of Ni.
Tables 1 and 2 show nickel-base alloys (C) to (K) and (O) to (R) which can be respectively used for the construction of the tube 24 or 24' and the wire 30 or 30'.
For the comparison, conventional alloys (A), (B) and (L) to (N) are shown in these tables. In Tables 3 and 4, there are `~
respectively shown the characteristics of the alloys (A) to tR), in which (1) indicates weight increase by oxidation, (2) thermo-electromotive force and (3) change in thermo-electromotive force by aging. These data were obtained under the following test conditions, in which:
(~) weight increase by oxidation Supplied gas: the atmosphere Temperature: 1100C
Operation hours: 50 hr.
(2) thermo-electromotive force before aging test Temperature: 1100C in the case of (A) to (K) 1000C in the case of (L) to (R)
(3) change in thermo-electromotive force by aging Supplied gas: the atmosphere Temperature: 1100C
Operation hours: 100 hr. in the cases of (A) to (K) ` ` ' 108596q . . ~ ~
NICXEL-BASE ALLOYS FOR THE TUBES (24 or 24') _ Composition (%) Type Note Cr Al Si Zr Nb Ti R.E.*
_ , : .
(A) 10 _ _ _ _ _ _ alloy .
(B) 10 _ _ _ _ _ _ ~
_ .
(C) 20 3 _ . _ _ _ 0.5 According to _ (D) 10 _ 0.5 _ _ _ 0.5 ..
_ _ I :' (E) 15 _ _ 0.2 _ _ 0.5 ..
. _ I ... .......
(F) 20 _ _ _ 0.5 _ 0.5 .. ~ .
.. .
(G) 15 _ _ _ _ 0.3 0.5 .-(H) 10 1.0 0.3 _ _ _ 0.5 ..
(I) 10 _ 0.5 0.2 _ _ ¦ 0.5 -_ . (J) 20 3 _ 0.1 1.0 _ 0.3 ..
_ (K) 20 ~ ~- 1.0 _ 1.0 _ 0.2 .
*R.E: Mischmetal (Ce50%+La50%) .~
., , .
108596q NICKEL-BASE ALLOYS FOR THE WIRES(30 or 30') I _ _ Composition (%) Type Note Al Si Mn R.E.*
~ ~ ~=
. ._ .
(O) 5.0 _ _ 0.5 According to the invention I
_ . . . . .. _.__ ..
(P) _ 2.0 _ 0.5 _ "
(Q) _ 5.0 _ 0.5 . . _ .. ._ ~
(R) 2.0 2.0 _ 0.5 "
. . ~
- *R.E: Mischmetal (Ce50%+La50%) 108596~7 EXPERIMENTAL DATA ON THE NICKEL-BASE
ALLOYS FOR THE TUBE (24 or 24') . ~ ~
. Data .
. .
~1~ (2) (3) . , Wt. increase by Thermo- Change in Thermo-oxidation force beforeelectromotive . (~g/mm ) aging test force by aging . . .. ...
50hr 1100C 100hr Atmosphere Atmosphere .. _.................... .
(A) 30 36 +0.1 . . . ... _ . _ (B)20 23 +0.05 (C) 6 21 +0.01 . .... __ . .. .
(D) 15 .. 35 +0.03 .. _ .~
(E) 10 25 +0.02 _._ . ._ (F) 8 23 +0.02 . .
(G) 10 , 25 +0.03 (H) 13 35 +0.03 (I) 15 36 +0.03 (J) 7 20 +0.01 .. .
(K) 10 20 +0.01 .
~08596~7 ExpERIMENlrAL DATA ON THE NICKEL-BASE
ALLOYS FOR THE WIRES ( 30 or 30 ' ) ~ _ _ --- Data (1) (2) ~3) Data ~ ....
Wt. increase byelectromotiveChange in Thermo-oxidation force beforeelectromotive . (~g/mm ) tmV) force by aging 1100C . 1100C
50hr 1000C 50hr .
Atmosphere Atmosphere . .
(L) 200 -88 -0 . 05 ... ... _ .... __ . _ .. _ (M) 190 --10 .1 .. ~ . . .. _ _ (N) 200 -15 . 9 -0 . 05 ..
(O) 140 -16 . 5 -0 . 01 .. . .. ..... .....
._ . , . .. _ . _ _ .
(P) 120 -9 . 8 -0. 01 . .. .. _ . .. _ . (Q) 90 -10.5 -0.00 (R) 50 --12. 8 --0 . 01 -~o8596q ~ `
As is well understood from these Tables 1 to 4, the alloys (C) to (K) for the construction of the tube 24 or 24' and the alloys (O) to (R) for the wire 30 or 30' respec~ively have improved characteristics with respect to corrosion resistance, thermal electro-motive-force ' '' and durability ln high temperature compared with the respective conventional alloys (A), (B) and (L) to (N).
According to the several experiments regarding the nickel-base alloys of various compositions,the following results were further obtained: -In the case of alloys for the tube (24 or 24') -(a) The addition of more than 1~ of rare-earth elements such as'lanthanum (La),cerium (Ce), samarium (Sm) ' and praseodymium''(Pr) into each of the nickel-base alloys causeslremarkable decrease in hot working characteristic of the tube. ' (b) If chromium (Cr) is decreased below 5%, the corrosion resistance of the alloy goes down sharply, more than 25% of chromium (Cr) content causes not only a ~ .
cm~rk~ly drop in hot working characteristic of the ~v alloy but also a drop ~ the thermo-electromotive force of the alloy.
(c~ The addition of more than 5% of aluminum (Al) into the alloy lowers the cold working characteristic of the alloy.
108S96q (d) The addition of more than 1% of silicon (Si), zirconium (Zr), titanium (Ti) and/or niobium (Nb) to the alloy does slightly enhance the corrosion resistance of the alloy, but lowers the thermo-electromotive force of the alloy.
In the case of alloys for the wire (30 or 30') (e) The addition of more than 7% of aluminium (Al) and/or silicon (Si) to each of the nickel-base alloys causes the cold working characteristic of the alloy to decrease.
Furthermore, if aluminium (Al) is decreased below 2~ and silicon (Si) is zero, the corrosion resistance characteristic of the alloy is hardly improved.
tf) The corrosion resistance of the alloy is increased by addition of a trace of a rare-earth element or elements.
However, the addition of more than 1% lowers the hot working characteristic and the corrosion resistance of the alloy.
Referring to Figs. 4 and 5, particularly to Fig. 4, there is shown an entire apparatus employing therein the temper-ature probe of Fig. 2. The apparatus comprises the thermocouple probe, a portion of an extension or compensation wire 36 and a transition fitting 38 therebetween.
' , , 108596~7 Since the construction of the probe of Fig. 2 has been explained in detail hereinbefore, description about it will be omitted here. A cross sectional view of the sensing element is shown in Fig. 5.
The portion of the extension wire 36 comprises two electrically conductive wires 40 which transmit current developed at the measuring junction 32 to a remote utilization device (not shown) for any intended purpose. Preferably, the wires 40 are constructed of materials having substantially the same thermo-electric~l characteristics as those of the tube 24 and the wire 30 respectively. Each wire 40 is encased in insulation (such as polyethylene insulation), the two wires 40 being further , supported and insulated with a woven glass fiber jacket 42 and a silicon rubber tube 44. The jacket 42 and insulation are stripped away to provide free lengths of the conductive wires 40 which are respectively welded to the tube 24 and the wire 30 of the thermocouple probe and typically brazed to -produce permanent electrical junctions 46.
In order to protect the electrical junctions 46 and provide a relatively rigid coupling between the thermocouple probe and the extension wire 36, the transition fitting 38 is employed for joining the two 108S96q elements. In this embodiment, the transition fitting 38 comprises an outer cylindrical casing 48 made of a heat resisting metal such as stainless steel, having at its one end a small diameter externally threaded portion 50 terminating in a radial shoulder portion 52.
The casing 48 is formed at its other end with a thin cylindrical portion 54 terminating in the radial shoulder portion 52. The shoulder portion 52 is used for facili-tating acceptance and seating of the thermocouple probe in a threaded bore formed in a suitable support member (not shown) such as an exhaust tube of an internal com-bustion engine. As shown, the cylindrical casing 48 is arranged to hold therein generally half a section of the fJ~cr~oco /c ~robc - above-mentioned s4~ing ~cment, that is the section containing the open end 28 of the tube 24. Within the outer cylindrical casing 48 is tightly disposed an inner cylindrical holder 56 which has a small diameter section 56a positioned in the externally threaded portion 50 of the casing 48 and a large diameter section 56b positioned in the shoulder and the thin cylindrical portions 52 and 54, respectively, of the casing 48. The small diameter section 56a protrudes outwardly from the casing 48 and the large diameter section 56b also protrudes from the casing 48, as shown. The cylindrical holder 56 is made of a chemically stable insulating solid -` 108596!7 material such as alumina ceramic and is formed with a longitudinally extending through bore consisting of a small diameter bore section 58a and a large diameter bore section 58_, the small diameter bore section 58a receiving therein the tube 24 of the probe. For tight setting of the tube 24 in the bore section 58a, alumina cement is filled in a clearance defined between the outer cylindrical surface of the tube 24 and the -inner cylindrical surface of the bore section 58a. Designated by numeral 60 is a metal gasket which is tightly disposed between - ~
the inner surface of the casing 48 and the outer surface of the -holder 56. In order to tightly fix the end portions of the extension wires 40 to the transition fitting 38, a generally conical supporter 62 made of an insulating material such as fluorine-containing plastics (Teflon) (registered Trade Mark) is used, which has two parallel through bores (no numerals) for respectively receiving therein the end portions of the wires 40 and is attached to the large diameter section 56_ of the cylindrical holder 56 at a large diameter portion thereof by the aid of a metal cylinder 64. As shown, the metal cylinder 64 has at its one end a flange 64a engaged via a metal ring 66 with an inwardly bent portion 54a of the thin cylindrical portion 54 of casing 48, and at its other end a flange 64_ engaged , - . . ~ .
, . :' ~ -. ` :
108596!7 .
~ via a plastic ring 68 (such as'Teflon ring) with a v' shoulder formed at the large diameter portion of the supporter 62. The conical surface of the supporter 62 is covered with an enlarged extension section of the aforementioned silicon rubber tube 44. The bore 58b thus enclosed receives therein the before-mentioned permanent electrical junctions 46 and is packed with an alumina cement 70 for tightly holding the junctions 46. Numeral 72 is a wire for supporting the wires 40 projected into the bore 58b.
.
, ,
Operation hours: 100 hr. in the cases of (A) to (K) ` ` ' 108596q . . ~ ~
NICXEL-BASE ALLOYS FOR THE TUBES (24 or 24') _ Composition (%) Type Note Cr Al Si Zr Nb Ti R.E.*
_ , : .
(A) 10 _ _ _ _ _ _ alloy .
(B) 10 _ _ _ _ _ _ ~
_ .
(C) 20 3 _ . _ _ _ 0.5 According to _ (D) 10 _ 0.5 _ _ _ 0.5 ..
_ _ I :' (E) 15 _ _ 0.2 _ _ 0.5 ..
. _ I ... .......
(F) 20 _ _ _ 0.5 _ 0.5 .. ~ .
.. .
(G) 15 _ _ _ _ 0.3 0.5 .-(H) 10 1.0 0.3 _ _ _ 0.5 ..
(I) 10 _ 0.5 0.2 _ _ ¦ 0.5 -_ . (J) 20 3 _ 0.1 1.0 _ 0.3 ..
_ (K) 20 ~ ~- 1.0 _ 1.0 _ 0.2 .
*R.E: Mischmetal (Ce50%+La50%) .~
., , .
108596q NICKEL-BASE ALLOYS FOR THE WIRES(30 or 30') I _ _ Composition (%) Type Note Al Si Mn R.E.*
~ ~ ~=
. ._ .
(O) 5.0 _ _ 0.5 According to the invention I
_ . . . . .. _.__ ..
(P) _ 2.0 _ 0.5 _ "
(Q) _ 5.0 _ 0.5 . . _ .. ._ ~
(R) 2.0 2.0 _ 0.5 "
. . ~
- *R.E: Mischmetal (Ce50%+La50%) 108596~7 EXPERIMENTAL DATA ON THE NICKEL-BASE
ALLOYS FOR THE TUBE (24 or 24') . ~ ~
. Data .
. .
~1~ (2) (3) . , Wt. increase by Thermo- Change in Thermo-oxidation force beforeelectromotive . (~g/mm ) aging test force by aging . . .. ...
50hr 1100C 100hr Atmosphere Atmosphere .. _.................... .
(A) 30 36 +0.1 . . . ... _ . _ (B)20 23 +0.05 (C) 6 21 +0.01 . .... __ . .. .
(D) 15 .. 35 +0.03 .. _ .~
(E) 10 25 +0.02 _._ . ._ (F) 8 23 +0.02 . .
(G) 10 , 25 +0.03 (H) 13 35 +0.03 (I) 15 36 +0.03 (J) 7 20 +0.01 .. .
(K) 10 20 +0.01 .
~08596~7 ExpERIMENlrAL DATA ON THE NICKEL-BASE
ALLOYS FOR THE WIRES ( 30 or 30 ' ) ~ _ _ --- Data (1) (2) ~3) Data ~ ....
Wt. increase byelectromotiveChange in Thermo-oxidation force beforeelectromotive . (~g/mm ) tmV) force by aging 1100C . 1100C
50hr 1000C 50hr .
Atmosphere Atmosphere . .
(L) 200 -88 -0 . 05 ... ... _ .... __ . _ .. _ (M) 190 --10 .1 .. ~ . . .. _ _ (N) 200 -15 . 9 -0 . 05 ..
(O) 140 -16 . 5 -0 . 01 .. . .. ..... .....
._ . , . .. _ . _ _ .
(P) 120 -9 . 8 -0. 01 . .. .. _ . .. _ . (Q) 90 -10.5 -0.00 (R) 50 --12. 8 --0 . 01 -~o8596q ~ `
As is well understood from these Tables 1 to 4, the alloys (C) to (K) for the construction of the tube 24 or 24' and the alloys (O) to (R) for the wire 30 or 30' respec~ively have improved characteristics with respect to corrosion resistance, thermal electro-motive-force ' '' and durability ln high temperature compared with the respective conventional alloys (A), (B) and (L) to (N).
According to the several experiments regarding the nickel-base alloys of various compositions,the following results were further obtained: -In the case of alloys for the tube (24 or 24') -(a) The addition of more than 1~ of rare-earth elements such as'lanthanum (La),cerium (Ce), samarium (Sm) ' and praseodymium''(Pr) into each of the nickel-base alloys causeslremarkable decrease in hot working characteristic of the tube. ' (b) If chromium (Cr) is decreased below 5%, the corrosion resistance of the alloy goes down sharply, more than 25% of chromium (Cr) content causes not only a ~ .
cm~rk~ly drop in hot working characteristic of the ~v alloy but also a drop ~ the thermo-electromotive force of the alloy.
(c~ The addition of more than 5% of aluminum (Al) into the alloy lowers the cold working characteristic of the alloy.
108S96q (d) The addition of more than 1% of silicon (Si), zirconium (Zr), titanium (Ti) and/or niobium (Nb) to the alloy does slightly enhance the corrosion resistance of the alloy, but lowers the thermo-electromotive force of the alloy.
In the case of alloys for the wire (30 or 30') (e) The addition of more than 7% of aluminium (Al) and/or silicon (Si) to each of the nickel-base alloys causes the cold working characteristic of the alloy to decrease.
Furthermore, if aluminium (Al) is decreased below 2~ and silicon (Si) is zero, the corrosion resistance characteristic of the alloy is hardly improved.
tf) The corrosion resistance of the alloy is increased by addition of a trace of a rare-earth element or elements.
However, the addition of more than 1% lowers the hot working characteristic and the corrosion resistance of the alloy.
Referring to Figs. 4 and 5, particularly to Fig. 4, there is shown an entire apparatus employing therein the temper-ature probe of Fig. 2. The apparatus comprises the thermocouple probe, a portion of an extension or compensation wire 36 and a transition fitting 38 therebetween.
' , , 108596~7 Since the construction of the probe of Fig. 2 has been explained in detail hereinbefore, description about it will be omitted here. A cross sectional view of the sensing element is shown in Fig. 5.
The portion of the extension wire 36 comprises two electrically conductive wires 40 which transmit current developed at the measuring junction 32 to a remote utilization device (not shown) for any intended purpose. Preferably, the wires 40 are constructed of materials having substantially the same thermo-electric~l characteristics as those of the tube 24 and the wire 30 respectively. Each wire 40 is encased in insulation (such as polyethylene insulation), the two wires 40 being further , supported and insulated with a woven glass fiber jacket 42 and a silicon rubber tube 44. The jacket 42 and insulation are stripped away to provide free lengths of the conductive wires 40 which are respectively welded to the tube 24 and the wire 30 of the thermocouple probe and typically brazed to -produce permanent electrical junctions 46.
In order to protect the electrical junctions 46 and provide a relatively rigid coupling between the thermocouple probe and the extension wire 36, the transition fitting 38 is employed for joining the two 108S96q elements. In this embodiment, the transition fitting 38 comprises an outer cylindrical casing 48 made of a heat resisting metal such as stainless steel, having at its one end a small diameter externally threaded portion 50 terminating in a radial shoulder portion 52.
The casing 48 is formed at its other end with a thin cylindrical portion 54 terminating in the radial shoulder portion 52. The shoulder portion 52 is used for facili-tating acceptance and seating of the thermocouple probe in a threaded bore formed in a suitable support member (not shown) such as an exhaust tube of an internal com-bustion engine. As shown, the cylindrical casing 48 is arranged to hold therein generally half a section of the fJ~cr~oco /c ~robc - above-mentioned s4~ing ~cment, that is the section containing the open end 28 of the tube 24. Within the outer cylindrical casing 48 is tightly disposed an inner cylindrical holder 56 which has a small diameter section 56a positioned in the externally threaded portion 50 of the casing 48 and a large diameter section 56b positioned in the shoulder and the thin cylindrical portions 52 and 54, respectively, of the casing 48. The small diameter section 56a protrudes outwardly from the casing 48 and the large diameter section 56b also protrudes from the casing 48, as shown. The cylindrical holder 56 is made of a chemically stable insulating solid -` 108596!7 material such as alumina ceramic and is formed with a longitudinally extending through bore consisting of a small diameter bore section 58a and a large diameter bore section 58_, the small diameter bore section 58a receiving therein the tube 24 of the probe. For tight setting of the tube 24 in the bore section 58a, alumina cement is filled in a clearance defined between the outer cylindrical surface of the tube 24 and the -inner cylindrical surface of the bore section 58a. Designated by numeral 60 is a metal gasket which is tightly disposed between - ~
the inner surface of the casing 48 and the outer surface of the -holder 56. In order to tightly fix the end portions of the extension wires 40 to the transition fitting 38, a generally conical supporter 62 made of an insulating material such as fluorine-containing plastics (Teflon) (registered Trade Mark) is used, which has two parallel through bores (no numerals) for respectively receiving therein the end portions of the wires 40 and is attached to the large diameter section 56_ of the cylindrical holder 56 at a large diameter portion thereof by the aid of a metal cylinder 64. As shown, the metal cylinder 64 has at its one end a flange 64a engaged via a metal ring 66 with an inwardly bent portion 54a of the thin cylindrical portion 54 of casing 48, and at its other end a flange 64_ engaged , - . . ~ .
, . :' ~ -. ` :
108596!7 .
~ via a plastic ring 68 (such as'Teflon ring) with a v' shoulder formed at the large diameter portion of the supporter 62. The conical surface of the supporter 62 is covered with an enlarged extension section of the aforementioned silicon rubber tube 44. The bore 58b thus enclosed receives therein the before-mentioned permanent electrical junctions 46 and is packed with an alumina cement 70 for tightly holding the junctions 46. Numeral 72 is a wire for supporting the wires 40 projected into the bore 58b.
.
, ,
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A thermocouple probe comprising:
a tube member having a closed end and an open end and made of a nickel-based alloy containing from 5 to 25% by weight chromium and one or more of:
(a) rare earth element in an amount not exceeding 1%
by weight;
(b) aluminium in an amount not exceeding 5% by weight;
and (c) one or more of the elements silicon, zirconium, titanium and niobium, provided that each element does not exceed 1% by weight;
the balance being nickel;
a wire member disposed in and axially extending through said tube member and having one end welded to an inner wall of said closed end of said tube member, said wire member being made of a nickel-based alloy containing one or more of:
(d) aluminium in an amount not exceeding 7% by weight;
(e) silicon in an amount not exceeding 7% by weight, provided that the sum of aluminium and silicon does not exceed 10% by weight;
(f) rare earth element in an amount not exceeding 1%
by weight; and (g) one or more of the elements carbon, cobalt, manganese and iron, provided that the sum of these elements does not exceed 1% by weight;
the balance being nickel; and an electrically insulating material filling said tube member so as to support said wire member substantially immovably in said tube member.
a tube member having a closed end and an open end and made of a nickel-based alloy containing from 5 to 25% by weight chromium and one or more of:
(a) rare earth element in an amount not exceeding 1%
by weight;
(b) aluminium in an amount not exceeding 5% by weight;
and (c) one or more of the elements silicon, zirconium, titanium and niobium, provided that each element does not exceed 1% by weight;
the balance being nickel;
a wire member disposed in and axially extending through said tube member and having one end welded to an inner wall of said closed end of said tube member, said wire member being made of a nickel-based alloy containing one or more of:
(d) aluminium in an amount not exceeding 7% by weight;
(e) silicon in an amount not exceeding 7% by weight, provided that the sum of aluminium and silicon does not exceed 10% by weight;
(f) rare earth element in an amount not exceeding 1%
by weight; and (g) one or more of the elements carbon, cobalt, manganese and iron, provided that the sum of these elements does not exceed 1% by weight;
the balance being nickel; and an electrically insulating material filling said tube member so as to support said wire member substantially immovably in said tube member.
2. A thermocouple probe according to Claim 1, in which the outer surface of said tube member has a coating comprising one or more of A12O3, Cr2O3, SiO2, TiO2 BeO and ZrO2.
3. A thermocouple probe according to Claim 1, or Claim 2, in which said tube member is formed at its closed end with a portion of reduced diameter and said wire member is formed at said one end with a portion of reduced diameter.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14615876A JPS5370888A (en) | 1976-12-07 | 1976-12-07 | Cooaxial type thermocouple |
| JP51-146158 | 1976-12-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1085967A true CA1085967A (en) | 1980-09-16 |
Family
ID=15401433
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA292,514A Expired CA1085967A (en) | 1976-12-07 | 1977-12-06 | Thermocouple probe |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5370888A (en) |
| CA (1) | CA1085967A (en) |
| DE (1) | DE2754271A1 (en) |
| GB (1) | GB1559659A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4460802A (en) * | 1982-12-15 | 1984-07-17 | Westinghouse Electric Corporation | Radially activated thermocouple assembly |
| JPH01233331A (en) * | 1988-03-14 | 1989-09-19 | Furuya Kinzoku:Kk | Sheathed thermocouple |
| AU628936B2 (en) * | 1989-02-17 | 1992-09-24 | Nicrobell Pty Limited | Pyrometric thermoelectric sensor |
| DE19953142A1 (en) * | 1999-09-14 | 2001-03-15 | Emitec Emissionstechnologie | Sheathed conductor arrangement for corrosive environmental conditions and method for producing a sheathed conductor arrangement |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5545623B2 (en) * | 1973-06-26 | 1980-11-19 | ||
| JPS568903B2 (en) * | 1973-08-30 | 1981-02-26 |
-
1976
- 1976-12-07 JP JP14615876A patent/JPS5370888A/en active Pending
-
1977
- 1977-12-06 CA CA292,514A patent/CA1085967A/en not_active Expired
- 1977-12-06 DE DE19772754271 patent/DE2754271A1/en not_active Withdrawn
- 1977-12-07 GB GB5089877A patent/GB1559659A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1559659A (en) | 1980-01-23 |
| JPS5370888A (en) | 1978-06-23 |
| DE2754271A1 (en) | 1978-06-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |