CA1087757A - Thermocouple probe - Google Patents
Thermocouple probeInfo
- Publication number
- CA1087757A CA1087757A CA292,500A CA292500A CA1087757A CA 1087757 A CA1087757 A CA 1087757A CA 292500 A CA292500 A CA 292500A CA 1087757 A CA1087757 A CA 1087757A
- Authority
- CA
- Canada
- Prior art keywords
- tube
- sleeve
- thermocouple probe
- metal
- disposed
- 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
Links
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
A wire which is dissimilar in material from a tube is concentrically disposed in the tube and connected at its one end to a closed end of the tube to form a measuring junction. A metal casing is disposed about the tube through an insulator, and a pair of compensation wires are respectively welded to the tube and the wire to form permanent electric junctions. The electric junctions are embedded in another insulator around which a metal sleeve is disposed so as to isolate the interior of the metal sleeve from the open air.
A wire which is dissimilar in material from a tube is concentrically disposed in the tube and connected at its one end to a closed end of the tube to form a measuring junction. A metal casing is disposed about the tube through an insulator, and a pair of compensation wires are respectively welded to the tube and the wire to form permanent electric junctions. The electric junctions are embedded in another insulator around which a metal sleeve is disposed so as to isolate the interior of the metal sleeve from the open air.
Description
108~757 FIELD OF THE INVENTION
The present invention relates in general to a temperature sensing device and more particularly to a thermocouple probe which is highly suited for sensing the temperature of the exhaust gases issued from an automotive internal combustion engine.
BACKGROUND OF THE INVENTION
Modern motor vehicles with internal combustion engines are now invariably equipped with exhaust conduit systems having so-called exhaust gas purifying equipment, such as catalytic converters and thermal reactors, for converting harmfu compounds such as HC, CO and NOx in the exhaust gases into harmless compounds such as H2O, CO2 and N2. In order to maintain optimum operation of this gas purifying equipment, it is required to check or monitor the temperature of the gases passing through the equipment by using temperature sensors disposed in the equipment.
Usually, the sensors are located in positions where highest temperature, most severe vibration, and exposure to water, and stone attack occur. Thus, in practical use, the position of these sensors in the equipment must be carefully selected by taking the above-mentioned facts into consideration.
Hitherto, two types of thermocouple temperature sensors have been widely used for the above-mentioned -~ -2-1()8775~
equipment, one of which is a type comprising two dissimilar metal wires connected at their one ends to form a so-called hot or measuring junction, a protecting tube spacedly enclosing the two wires, and an insulating material filled within the tube for insulating the wires and the tube from one and another, and the other of which is a type sometimes called a "tube type" comprising a metal wire, a metal tube which is dissimilar in material from the metal wire which it encloses, and an insula_ing material filled within the metal tube, an end of the metal wire being welded or brazed to a closed end of the metal tube to form the - measuring junction.
Several experiments have revealed that the "tubeitype"
thermocouple tempera~re sensor exhibits better response charac-teristics and higher durability in practical use than the former.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a "tube type" thermocouple temperature sensor which has an improved construction.
It is another object of the invention to provide an improved thermocouple temperature sensor which is most appropriate to measure the temperature of the exhaust gases issued from an internal combustion engine.
It is still another object of the present invention ' 1087'757 to provide a thermocouple probe which can be mounted on a suitable support member such as the exhaust tube in a very simple manner.
It is a further object of the present invention to .
provide a thermocouple probe which has increased durability and longer life in comparision with the conventional thermocouple probes.
According to the present invention, there is provided a thermocouple probe comprising an electrically conducting tube with an open end and a closed end, the tube being filled with an insulating material; an electrically condu~ting wire dissimilar in material from the tube, the wire being concen-trically disposed in the tube and welded at its one end to the closed end of the tube to form a measuring junction, the other end of the wire extending outwardly beyond the open end of the tube; a first insulator tightly disposed about a longitudinally intermediate portion of the tube; a metal casing tightly disposed about the first insulator so as to be insulated from the tube; a pair of compensation wires respectively connected to the tube and the conducting wire at a position near the open end of the tube to form respective permanent electrical junctions; a second insulator embedding therein the permanent electrical junctions; a metal sleeve disposed about the second insulator in such a manner that a longitudinal end of the sleeve sealingly engages with the metal casing;
`'' ' ' and means for detachably connecting the metal casing to a support member.
SUMMARY OF THEDR~
Other objects and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in whi~h:
Fig. 1 is a longitudinal sectio.. view of a preferred thermocouple probe of the present invention;
Fig. 2 is a section view taken along the line II-II
of Fig. l;
Fig. 3 is a view similar to Fig. 1 of an alternative embodiment of the invention;
Fig. 4 is a sectional view taken along the line IV-IV
of Fig. 3; and Fig. 5 is a view showing the thermocouple probe of Fig. 3 mounted in a suitable support member.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figs. 1 and 2, particularly to Fig. 1, there i3 illustrated a firs~;preferred embodiment showing a , thermocouple probe generally designaied by numeral 10. The thermocouple probe 10 comprises a sensing element 12, a portion of extension cable 14 and a casing 16 therebetween.
The sensing element 12 comprises a thin tube 18 '~' 108775~7 constructed of CHROMEL (R.T.M.) metal. The tube is closed at its one ena by an end wall 18a and open at its other end (no numeral). Longitudinally and concentrically disposed in the tube 18 is a metal wire 20 made of AL-uMEL (R.T.M.) metal which has one end thereof welded to the end wall 18a at point 22 and the other end thereof passed through and spaced from the open end of the tube 18. With this, at the point 22, a so-called measur-ing junction is formed which, in conjunction with a cold or reference junction (not shown) formed at the other ends of a pair of compensation wires 26, produces an electric current flow when exposed to a source of heat; this effect being produced by the transfer of electrons between the dissimilar metals 18 and 20. The cavity of the tube 18 is filled with a pow~ered insulator 24 such as powdered magnesium oxide (MgO) to electrically isolate the wire 20 other than the junction portion 22 from the itube 18. Fig. 2 shows a cross section of an intermediate portion of the sensing element 12.
";The extension cable 14 comprises the afore-mentioned pair of electrically conductive compensation wires 26 which are adapted to transmit current developed at the measuring ;junction 22 to a remote utilization device (not shown) via the reference junction for any intended purpose. Each wire 26 is encased in insulation (such as ' :', ,' polyethylene insulation), the pair of wires 26 being further supported and insu'ated with a woven glass fiber jacket 28 or a silicon rubber tube. During manufacture, the jacket 28 and insulation are stripped away to provide free lengths of the conductive wires 26 which are respectively welded or brazed to the tube 18 and the wire 20 of the sensing element 12 to produce permanent electrical junctions 30.
In order to protect the electrical junctions 30 and provide a relatively rigid coupling between the sensing element 12 and the extension cable 14, the casing 16 is employed for joining the two elements. In this embodiment, the casing 16 comprises an outer or first cylindrical casing portion 32 made of a heat resisting metal, such as stainless steel, having at its one end a small diameter externally threaded portion 34 terminating in a radial shoulder portion 36. The casing 32 is formed at its other end with a thin cylindrical portion 38 terminating in the radial shoulder portion 36. The shoulder portion 36 is used for facilitating acceptance and seating of the outer cylindrical casing 32 in a threaded bore formed in a suitable support member (not shown) such as an exhaust tube of an internal combustion engine. As shown, the first cylindrical casing portion 32 is formed with a stepped through bore in which ~087'757 a cylindrical holder is snugly received. The cylindrical holder has a smaller diameter end which projects out of the stepped bore, and a larger diameter end which extends out of the o~her end of the stepped bore. The end of the first cylindrical casing portion 32 from which the smaller diameter end of the cylindrical holder projects is that end on which the afore-mentioned threaded bore is formed as can be clearly seen from the figure. The smaller diame~er section 40a has a portion (no numeral) which protrudes outwardly from the casing 32 and the larger diameter section 40_ also has a portion (no numeral) protnuding from the casing 32, as shown. The cylindrical , holder 40 is made of a chemically stable insulating solid material ; such as alumina ceramic and is formed-with a longitudinally extending stepped through bore consisting of a smaller diameter , bore section 42a and a larger diameter bore section 42b, the smaller diameter bore section 42a receiving therein the tube 18 of the sensing element 12. To set the tube 18 in the bore section 42a, alumina cement is filled in the clearance defined between the outer cylindrical surface of the tube 18 and the inner cylindrical surface of the bore section 42a. Designated by numeral 44 is a metal gasket which is tightly disposed between the inner chamfered surface of the casing 32 and the outer chamfered surface of the holder 40. In order to tightly fix the end portion of the extension wires 26 to the casing 16, a generally conical supporter 46 made of an insulating material such as a fluorine-based plastics, e.g.
TEFLON (registered trade mark) is used, which has two parallel through bores for respectively receiving the end portions of the wires 26 and is attached to the larger diameter section 40b of the cylindrical holder 40 at a larger diameter portion thereof by the aid of a second cylindrical metal casing or metal sleeve 50. As shown, the metal cylinder 50 has at its ~ 10 one end an external flange 50a engaged via a metal ring 52 ; with an internal flange portion 38_ of the thin cylindrical portion 38 of the casing 22, and at its other end an internal , ~
flange 50b engaged via a plastic ring 54, such as a TEFLON
(registered trade mark) ring, with a shoulder formed at the larger diameterportion of the supporter 46. The conical surface of the supporter 46 is covered with an enlarged extension of the aforementioned jacket 28. The bore 42b thus enclosed receives therein the before-mentioned permanent electrical junctions 30. Within the bore 42b is filled an alumina cement 56 for tightly holding the junctions 30.
Numeral 58 is a ring for banding a portion of the wires 26 projected into the bore 42_.
Referring to Figs. 3 and 4, particularly to Fig. 3, there is shown a second embodiment according to the invention. A thermocouple probe of this embodi-ment is generally designated by numeral 10' and comprises a sensing element 12', a portion of an extension or cable ; 14' and a casing 16' therebetween.
9e~
The sensing element 12'~ comprises the gene ally same parts as the sensing element 12 of the first embodiment 10. Thus, like numerals will refer to the corresponding parts of the element 12 for facilitation.
,, .
- The portion of the cable 14' comprises a pair of electrically conductive twisted compensation wires 26' ., which have thermoelectric characteristics very similar b to those of the tube 18 and the wire 20 of the sensing element 12'. As well shown in Fig. 4, each of the wires . .;
26' is encased by a flexible insulator 60 such as polyethylene having high heat water resistance, the pair of wires 26' thus encased being embedded in a solid cylindrical silicon rubber hose 62 and further covered i ~S~
; with a metal mesh 64 for prevention of electrical noizc.
The naked end of the wires 26', similar to the first embodiment, are respectively welded or brazed to the tube 18 and the wire 20 of the sensing element 12' to produce permanent electrical junctions 30'.
The casing 16' of the second embodiment comprises a first cylindrical casing portion 66 made of a heat resisting metal, such as stainless steel, having at its ~087757 one end an inwardly directed radial flange 68 and at a section near the end an outwardly directed radial flange 70. As shown, the first casing portion 66 is arranged to hold therein a generàlly middle portion of the sensing element 12'. Within the cylindrical casing 66 is tightly disposed a cylindrical holder 72 which is made of a chemically stable insulating solid material such as alumina ceramic. The cylindrical holder 72 has at its one end a smaller diameter section 72a which is projected outwardly and snugly disposed in an opening (no numeral) defined by the internal projection 68 of the cylindrical casing 66.
The holder 72 further has a central through bore 72_ in which the tube 18 of the sensing element 12' is secured via alumina cement compound. Within the first casing portion 66 is also disposed a heat resisting insulating adhesive 74, such as alumina cement for assurance of tight setting of the tube 18.
A conical-shaped metal co~er or second casing portion 76 is welded at its larger diameter end to the other end of the first cylindrical casing portion 66 while receiving therein the right end section of the sensing eleme~t 12'. A space (no numeral) defined between the inner conical surface of the metal cover 76 and the outer surface of the right hand end section of the sensing element 12' is packed with a powdered insulating .
B material 77 such as A12O3, MgO, SiO2, ZrO2, ~ BeO in :) powder form so as to tightly set the tube 18 in the casing 16' and insulate the tube 18 from the fitting , 16'. Preferably, a mixture of at least two of the above-, 5 stated materials is used. A metal sleeve 78 is used for providing a rigid connection between the conical metal cover 76 and the portion of the cable 14'. After , the respective longitudinal ends of the sleeve 78 are ,j S~,n,9~/C~
,~ disposed about the cmall diameter end of the conical-~ J 10 shaped metal cover 76 and an end of the portion of the ,~ cable 14', the ends are swaged or crimped in place by '`~ a tool suited for this particular purpose. It should . ~ .
j be noted that the deformation thus formed on the ends of the sleeve 78 causes a similar grooved deformation of each of the conical metal cover 76 and the portion of the cable 14' providing a rigid mechanical connection therewith and an effective mechanical seal for protection from external atmosphric- conditions. The enclosure defined within the metal sleeve 78 is packed with an insulating material such as silicon compound to provide support for the complete assembly as well as insulation for the electrical junctions 30' located therewithin.
The casing 16' further has a connecting sleeve 80 which cooperates with the afore-mentioned cylindrical casing 66 to readily but tightly fix the thermocouple probe 10' to a suitable support member in such a manner as will ~Se~e,~affef~
B be described ~i~late~ The connecting sleeve 80 is slidably disposed around a major portion of the cylindri-cal casing 66 such that a longitudinal end thereof is engageable with the radially extending flange 70 of the - cyllndrical casing 66. As shown, the connecting sleeve 80 is formed with an externally threaded portion 80a terminating in a flange 80b formed at one end of the sleeve 80.
10Referring to Fig. 5, there is shown a condition in which the thermocouple probe 10' of the second embodiment is detachably mounted in a suitable support member 82 suc~ as an exhaust tube of an internal combustion engine.
Designated by numeral 84 in this drawing is a retaining s~ q//c~
sleeve which is formed with a ~ diameter portion 84a interconnected with the remainder of the retaining sleeve 84 by a tapered section 84b, as shown. The smallcr diameter portion 84a of the retaining sleeve 84 is tightly disposed in a hole 82a formed in the support member 82.
If desired, the connection between the retaining sleeve 84 and the support member 82 may be made by welding.
The retaining sleeve 84 is formed with an internally threaded portion (no numeral) which is engageable with the afore-mentioned externally threaded portion 80a of the connecting sleeve 80. Thus, it will be clear that 7'75~7 the mounting of the thermocouple probe 10' on the support member 82 is achieved only by turning or retaining the connecting sleeve 80 to press the radially extending flange 70 to the tapered section 84b of the retaining sleeve 84. In other words, the mounting of the probe 10' is made without turning the main portion, such as the sensing element 12', of the probe 10', so that the compensation wires 26' are not twisted during the mounting operation of the probe 10'. Thus the probe 10' can - be readily set in a limited space such as a portion defined in the exhaust conduit of the internal combustion engine.~
; With the above-stated constructions of the first and second embodiments of the invention, the following merits are obtained.
(1) Since the thermocouple probe of the invention is constructed to electrically isolate the sensing element (12 or 12') from the connecting holder such as the metal casings 32 and 66, the sensing element can produce a reliable electric signal without electrical noises which will be transmitted to the metal casing 32 or 66 during the use.
The present invention relates in general to a temperature sensing device and more particularly to a thermocouple probe which is highly suited for sensing the temperature of the exhaust gases issued from an automotive internal combustion engine.
BACKGROUND OF THE INVENTION
Modern motor vehicles with internal combustion engines are now invariably equipped with exhaust conduit systems having so-called exhaust gas purifying equipment, such as catalytic converters and thermal reactors, for converting harmfu compounds such as HC, CO and NOx in the exhaust gases into harmless compounds such as H2O, CO2 and N2. In order to maintain optimum operation of this gas purifying equipment, it is required to check or monitor the temperature of the gases passing through the equipment by using temperature sensors disposed in the equipment.
Usually, the sensors are located in positions where highest temperature, most severe vibration, and exposure to water, and stone attack occur. Thus, in practical use, the position of these sensors in the equipment must be carefully selected by taking the above-mentioned facts into consideration.
Hitherto, two types of thermocouple temperature sensors have been widely used for the above-mentioned -~ -2-1()8775~
equipment, one of which is a type comprising two dissimilar metal wires connected at their one ends to form a so-called hot or measuring junction, a protecting tube spacedly enclosing the two wires, and an insulating material filled within the tube for insulating the wires and the tube from one and another, and the other of which is a type sometimes called a "tube type" comprising a metal wire, a metal tube which is dissimilar in material from the metal wire which it encloses, and an insula_ing material filled within the metal tube, an end of the metal wire being welded or brazed to a closed end of the metal tube to form the - measuring junction.
Several experiments have revealed that the "tubeitype"
thermocouple tempera~re sensor exhibits better response charac-teristics and higher durability in practical use than the former.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a "tube type" thermocouple temperature sensor which has an improved construction.
It is another object of the invention to provide an improved thermocouple temperature sensor which is most appropriate to measure the temperature of the exhaust gases issued from an internal combustion engine.
It is still another object of the present invention ' 1087'757 to provide a thermocouple probe which can be mounted on a suitable support member such as the exhaust tube in a very simple manner.
It is a further object of the present invention to .
provide a thermocouple probe which has increased durability and longer life in comparision with the conventional thermocouple probes.
According to the present invention, there is provided a thermocouple probe comprising an electrically conducting tube with an open end and a closed end, the tube being filled with an insulating material; an electrically condu~ting wire dissimilar in material from the tube, the wire being concen-trically disposed in the tube and welded at its one end to the closed end of the tube to form a measuring junction, the other end of the wire extending outwardly beyond the open end of the tube; a first insulator tightly disposed about a longitudinally intermediate portion of the tube; a metal casing tightly disposed about the first insulator so as to be insulated from the tube; a pair of compensation wires respectively connected to the tube and the conducting wire at a position near the open end of the tube to form respective permanent electrical junctions; a second insulator embedding therein the permanent electrical junctions; a metal sleeve disposed about the second insulator in such a manner that a longitudinal end of the sleeve sealingly engages with the metal casing;
`'' ' ' and means for detachably connecting the metal casing to a support member.
SUMMARY OF THEDR~
Other objects and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in whi~h:
Fig. 1 is a longitudinal sectio.. view of a preferred thermocouple probe of the present invention;
Fig. 2 is a section view taken along the line II-II
of Fig. l;
Fig. 3 is a view similar to Fig. 1 of an alternative embodiment of the invention;
Fig. 4 is a sectional view taken along the line IV-IV
of Fig. 3; and Fig. 5 is a view showing the thermocouple probe of Fig. 3 mounted in a suitable support member.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figs. 1 and 2, particularly to Fig. 1, there i3 illustrated a firs~;preferred embodiment showing a , thermocouple probe generally designaied by numeral 10. The thermocouple probe 10 comprises a sensing element 12, a portion of extension cable 14 and a casing 16 therebetween.
The sensing element 12 comprises a thin tube 18 '~' 108775~7 constructed of CHROMEL (R.T.M.) metal. The tube is closed at its one ena by an end wall 18a and open at its other end (no numeral). Longitudinally and concentrically disposed in the tube 18 is a metal wire 20 made of AL-uMEL (R.T.M.) metal which has one end thereof welded to the end wall 18a at point 22 and the other end thereof passed through and spaced from the open end of the tube 18. With this, at the point 22, a so-called measur-ing junction is formed which, in conjunction with a cold or reference junction (not shown) formed at the other ends of a pair of compensation wires 26, produces an electric current flow when exposed to a source of heat; this effect being produced by the transfer of electrons between the dissimilar metals 18 and 20. The cavity of the tube 18 is filled with a pow~ered insulator 24 such as powdered magnesium oxide (MgO) to electrically isolate the wire 20 other than the junction portion 22 from the itube 18. Fig. 2 shows a cross section of an intermediate portion of the sensing element 12.
";The extension cable 14 comprises the afore-mentioned pair of electrically conductive compensation wires 26 which are adapted to transmit current developed at the measuring ;junction 22 to a remote utilization device (not shown) via the reference junction for any intended purpose. Each wire 26 is encased in insulation (such as ' :', ,' polyethylene insulation), the pair of wires 26 being further supported and insu'ated with a woven glass fiber jacket 28 or a silicon rubber tube. During manufacture, the jacket 28 and insulation are stripped away to provide free lengths of the conductive wires 26 which are respectively welded or brazed to the tube 18 and the wire 20 of the sensing element 12 to produce permanent electrical junctions 30.
In order to protect the electrical junctions 30 and provide a relatively rigid coupling between the sensing element 12 and the extension cable 14, the casing 16 is employed for joining the two elements. In this embodiment, the casing 16 comprises an outer or first cylindrical casing portion 32 made of a heat resisting metal, such as stainless steel, having at its one end a small diameter externally threaded portion 34 terminating in a radial shoulder portion 36. The casing 32 is formed at its other end with a thin cylindrical portion 38 terminating in the radial shoulder portion 36. The shoulder portion 36 is used for facilitating acceptance and seating of the outer cylindrical casing 32 in a threaded bore formed in a suitable support member (not shown) such as an exhaust tube of an internal combustion engine. As shown, the first cylindrical casing portion 32 is formed with a stepped through bore in which ~087'757 a cylindrical holder is snugly received. The cylindrical holder has a smaller diameter end which projects out of the stepped bore, and a larger diameter end which extends out of the o~her end of the stepped bore. The end of the first cylindrical casing portion 32 from which the smaller diameter end of the cylindrical holder projects is that end on which the afore-mentioned threaded bore is formed as can be clearly seen from the figure. The smaller diame~er section 40a has a portion (no numeral) which protrudes outwardly from the casing 32 and the larger diameter section 40_ also has a portion (no numeral) protnuding from the casing 32, as shown. The cylindrical , holder 40 is made of a chemically stable insulating solid material ; such as alumina ceramic and is formed-with a longitudinally extending stepped through bore consisting of a smaller diameter , bore section 42a and a larger diameter bore section 42b, the smaller diameter bore section 42a receiving therein the tube 18 of the sensing element 12. To set the tube 18 in the bore section 42a, alumina cement is filled in the clearance defined between the outer cylindrical surface of the tube 18 and the inner cylindrical surface of the bore section 42a. Designated by numeral 44 is a metal gasket which is tightly disposed between the inner chamfered surface of the casing 32 and the outer chamfered surface of the holder 40. In order to tightly fix the end portion of the extension wires 26 to the casing 16, a generally conical supporter 46 made of an insulating material such as a fluorine-based plastics, e.g.
TEFLON (registered trade mark) is used, which has two parallel through bores for respectively receiving the end portions of the wires 26 and is attached to the larger diameter section 40b of the cylindrical holder 40 at a larger diameter portion thereof by the aid of a second cylindrical metal casing or metal sleeve 50. As shown, the metal cylinder 50 has at its ~ 10 one end an external flange 50a engaged via a metal ring 52 ; with an internal flange portion 38_ of the thin cylindrical portion 38 of the casing 22, and at its other end an internal , ~
flange 50b engaged via a plastic ring 54, such as a TEFLON
(registered trade mark) ring, with a shoulder formed at the larger diameterportion of the supporter 46. The conical surface of the supporter 46 is covered with an enlarged extension of the aforementioned jacket 28. The bore 42b thus enclosed receives therein the before-mentioned permanent electrical junctions 30. Within the bore 42b is filled an alumina cement 56 for tightly holding the junctions 30.
Numeral 58 is a ring for banding a portion of the wires 26 projected into the bore 42_.
Referring to Figs. 3 and 4, particularly to Fig. 3, there is shown a second embodiment according to the invention. A thermocouple probe of this embodi-ment is generally designated by numeral 10' and comprises a sensing element 12', a portion of an extension or cable ; 14' and a casing 16' therebetween.
9e~
The sensing element 12'~ comprises the gene ally same parts as the sensing element 12 of the first embodiment 10. Thus, like numerals will refer to the corresponding parts of the element 12 for facilitation.
,, .
- The portion of the cable 14' comprises a pair of electrically conductive twisted compensation wires 26' ., which have thermoelectric characteristics very similar b to those of the tube 18 and the wire 20 of the sensing element 12'. As well shown in Fig. 4, each of the wires . .;
26' is encased by a flexible insulator 60 such as polyethylene having high heat water resistance, the pair of wires 26' thus encased being embedded in a solid cylindrical silicon rubber hose 62 and further covered i ~S~
; with a metal mesh 64 for prevention of electrical noizc.
The naked end of the wires 26', similar to the first embodiment, are respectively welded or brazed to the tube 18 and the wire 20 of the sensing element 12' to produce permanent electrical junctions 30'.
The casing 16' of the second embodiment comprises a first cylindrical casing portion 66 made of a heat resisting metal, such as stainless steel, having at its ~087757 one end an inwardly directed radial flange 68 and at a section near the end an outwardly directed radial flange 70. As shown, the first casing portion 66 is arranged to hold therein a generàlly middle portion of the sensing element 12'. Within the cylindrical casing 66 is tightly disposed a cylindrical holder 72 which is made of a chemically stable insulating solid material such as alumina ceramic. The cylindrical holder 72 has at its one end a smaller diameter section 72a which is projected outwardly and snugly disposed in an opening (no numeral) defined by the internal projection 68 of the cylindrical casing 66.
The holder 72 further has a central through bore 72_ in which the tube 18 of the sensing element 12' is secured via alumina cement compound. Within the first casing portion 66 is also disposed a heat resisting insulating adhesive 74, such as alumina cement for assurance of tight setting of the tube 18.
A conical-shaped metal co~er or second casing portion 76 is welded at its larger diameter end to the other end of the first cylindrical casing portion 66 while receiving therein the right end section of the sensing eleme~t 12'. A space (no numeral) defined between the inner conical surface of the metal cover 76 and the outer surface of the right hand end section of the sensing element 12' is packed with a powdered insulating .
B material 77 such as A12O3, MgO, SiO2, ZrO2, ~ BeO in :) powder form so as to tightly set the tube 18 in the casing 16' and insulate the tube 18 from the fitting , 16'. Preferably, a mixture of at least two of the above-, 5 stated materials is used. A metal sleeve 78 is used for providing a rigid connection between the conical metal cover 76 and the portion of the cable 14'. After , the respective longitudinal ends of the sleeve 78 are ,j S~,n,9~/C~
,~ disposed about the cmall diameter end of the conical-~ J 10 shaped metal cover 76 and an end of the portion of the ,~ cable 14', the ends are swaged or crimped in place by '`~ a tool suited for this particular purpose. It should . ~ .
j be noted that the deformation thus formed on the ends of the sleeve 78 causes a similar grooved deformation of each of the conical metal cover 76 and the portion of the cable 14' providing a rigid mechanical connection therewith and an effective mechanical seal for protection from external atmosphric- conditions. The enclosure defined within the metal sleeve 78 is packed with an insulating material such as silicon compound to provide support for the complete assembly as well as insulation for the electrical junctions 30' located therewithin.
The casing 16' further has a connecting sleeve 80 which cooperates with the afore-mentioned cylindrical casing 66 to readily but tightly fix the thermocouple probe 10' to a suitable support member in such a manner as will ~Se~e,~affef~
B be described ~i~late~ The connecting sleeve 80 is slidably disposed around a major portion of the cylindri-cal casing 66 such that a longitudinal end thereof is engageable with the radially extending flange 70 of the - cyllndrical casing 66. As shown, the connecting sleeve 80 is formed with an externally threaded portion 80a terminating in a flange 80b formed at one end of the sleeve 80.
10Referring to Fig. 5, there is shown a condition in which the thermocouple probe 10' of the second embodiment is detachably mounted in a suitable support member 82 suc~ as an exhaust tube of an internal combustion engine.
Designated by numeral 84 in this drawing is a retaining s~ q//c~
sleeve which is formed with a ~ diameter portion 84a interconnected with the remainder of the retaining sleeve 84 by a tapered section 84b, as shown. The smallcr diameter portion 84a of the retaining sleeve 84 is tightly disposed in a hole 82a formed in the support member 82.
If desired, the connection between the retaining sleeve 84 and the support member 82 may be made by welding.
The retaining sleeve 84 is formed with an internally threaded portion (no numeral) which is engageable with the afore-mentioned externally threaded portion 80a of the connecting sleeve 80. Thus, it will be clear that 7'75~7 the mounting of the thermocouple probe 10' on the support member 82 is achieved only by turning or retaining the connecting sleeve 80 to press the radially extending flange 70 to the tapered section 84b of the retaining sleeve 84. In other words, the mounting of the probe 10' is made without turning the main portion, such as the sensing element 12', of the probe 10', so that the compensation wires 26' are not twisted during the mounting operation of the probe 10'. Thus the probe 10' can - be readily set in a limited space such as a portion defined in the exhaust conduit of the internal combustion engine.~
; With the above-stated constructions of the first and second embodiments of the invention, the following merits are obtained.
(1) Since the thermocouple probe of the invention is constructed to electrically isolate the sensing element (12 or 12') from the connecting holder such as the metal casings 32 and 66, the sensing element can produce a reliable electric signal without electrical noises which will be transmitted to the metal casing 32 or 66 during the use.
(2) Since the permanent electrical junctions 30 or 30' are embedded in an insulating material and the insulating material is tightly packed, the insulation between the junctions is assured more reliably.
(3) Since the sensing elements 12 or 12' of the thermo-couple probe are substantially and/or wholly covered by a metal cover including the metal casing and the metal sleeve, the probe will not be so readily damaqed by contact by impinging stones or the like during vehicle running.
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A thermocouple probe, comprising:
an electrically conducting tube with an open end and a closed end, said tube being filled with an insulating material:
an electrically conducting wire dissimilar in material from said tube, said wire being concentrically disposed in said tube and welded at its one end to said closed end of said tube to form a measuring junction, the other end of said wire extending outwardly beyond said open end of said tube;
a first insulator tightly disposed about a longitudinally intermediate portion of said tube;
a metal casing tightly disposed about said first insulator so as to be insulated from said tube;
a pair of compensation wires respectively connected to said tube and said conducting wire at a portion near said open end of said tube to form respective permanent electrical junctions;
a second insulator embedding therein said permanent electrical junctions;
a metal sleeve disposed about said second insulator in such a manner that a longitudinal end of said sleeve seal-ingly engages with said metal casing; and means for detachably connecting said metal casing to a support member.
an electrically conducting tube with an open end and a closed end, said tube being filled with an insulating material:
an electrically conducting wire dissimilar in material from said tube, said wire being concentrically disposed in said tube and welded at its one end to said closed end of said tube to form a measuring junction, the other end of said wire extending outwardly beyond said open end of said tube;
a first insulator tightly disposed about a longitudinally intermediate portion of said tube;
a metal casing tightly disposed about said first insulator so as to be insulated from said tube;
a pair of compensation wires respectively connected to said tube and said conducting wire at a portion near said open end of said tube to form respective permanent electrical junctions;
a second insulator embedding therein said permanent electrical junctions;
a metal sleeve disposed about said second insulator in such a manner that a longitudinal end of said sleeve seal-ingly engages with said metal casing; and means for detachably connecting said metal casing to a support member.
2. A thermocouple probe as claimed in claim 1, in which said means comprises an external thread formed around said metal casing.
3. A thermocouple probe as claimed in claim 1, in which said means comprises:
a flange portion formed on said metal casing to extend radially outwardly; and a connecting sleeve slidably disposed about said metal casing and having an externally threaded portion terminating in a radially extending flange formed on an end of said sleeve, the opposite end of said sleeve being engageable with said flange portion of said metal casing upon connection of said metal casing to said support member.
a flange portion formed on said metal casing to extend radially outwardly; and a connecting sleeve slidably disposed about said metal casing and having an externally threaded portion terminating in a radially extending flange formed on an end of said sleeve, the opposite end of said sleeve being engageable with said flange portion of said metal casing upon connection of said metal casing to said support member.
4. A thermocouple probe as claimed in claim 1, further comprising an adhesive sealing material which is disposed between the inner surface of said first insulating and the outer surface of said conducting tube.
5. A thermocouple probe as claimed in claim 1, in which said compensation wires have thermoelectric characteristic substantially the same as those of said electrically conducting tube and said electrically conducting wire.
6. A thermocouple probe as claimed in claim 1, further comprising a supporter of an insulating material, said supporter having two parallel through holes in which said compensation wires are respectively received, said supporter having an enlarged portion tightly disposed in said metal sleeve.
7. A thermocouple probe as claimed in claim 6, in which the other end of said metal sleeve is sealingly engaged, via a jacket member holding said compensation wires, with said supporter at a position other than said enlarged portion of said supporter.
8. A thermocouple probe as claimed in claim 1, in which the other end of said metal sleeve is sealingly engaged with a jacket member which holds therein said compensation wires.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP51-146157 | 1976-12-07 | ||
| JP14615776A JPS5370887A (en) | 1976-12-07 | 1976-12-07 | Temperature sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1087757A true CA1087757A (en) | 1980-10-14 |
Family
ID=15401412
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA292,500A Expired CA1087757A (en) | 1976-12-07 | 1977-12-06 | Thermocouple probe |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5370887A (en) |
| CA (1) | CA1087757A (en) |
| DE (1) | DE2754284A1 (en) |
| GB (1) | GB1578867A (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1209367A (en) * | 1982-10-08 | 1986-08-12 | Omer P.I. Cure | Immersion measuring probe for use in molten metals |
| GB2131606A (en) * | 1982-12-13 | 1984-06-20 | British Gas Corp | Hermetically sealed thermocouple |
| ITMI20111610A1 (en) * | 2011-09-07 | 2013-03-08 | Actek S R L | THERMOCOUPLE FOR BURNERS OF OVENS OR COOKTOPS |
| CN103134686A (en) * | 2012-12-21 | 2013-06-05 | 中国飞行试验研究院 | Water-cooling type measurement rake |
| CN103792017B (en) * | 2014-01-27 | 2016-04-06 | 常州腾龙汽车零部件股份有限公司 | Vehicle exhaust measures dedicated temperature sensor and preparation method thereof |
| EP3117193B1 (en) * | 2014-03-13 | 2020-10-07 | Castfutura S.p.A. | Thermocouple and method for making the same |
| JP2020046237A (en) * | 2018-09-18 | 2020-03-26 | 日本特殊陶業株式会社 | Temperature sensor and manufacturing method of temperature sensor |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5147477B2 (en) * | 1973-04-16 | 1976-12-15 |
-
1976
- 1976-12-07 JP JP14615776A patent/JPS5370887A/en active Pending
-
1977
- 1977-12-06 CA CA292,500A patent/CA1087757A/en not_active Expired
- 1977-12-06 DE DE19772754284 patent/DE2754284A1/en not_active Withdrawn
- 1977-12-07 GB GB5098477A patent/GB1578867A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5370887A (en) | 1978-06-23 |
| DE2754284A1 (en) | 1978-06-08 |
| GB1578867A (en) | 1980-11-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |