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Title:
THERMOCOUPLE AND METHOD FOR FASTENING THE SAME
Document Type and Number:
WIPO Patent Application WO/2016/157111
Kind Code:
A1
Abstract:
Thermocouple comprising: a temperature sensor (10) having a measuring end (13) intended to be exposed to a heat source and an end for an output electrical signal variable as a function of the temperature to which the measuring end (13) has been exposed; a supporting body (1) for said temperature sensor (10) and which supporting body (1) has fastening means intended to cooperate with the structure (2) of a use unit. The supporting body (1) has at least one appendage (401) fastening, by a press snap fit (601), into a corresponding snap seat (102).

Inventors:
OFFREDI, Giorgio (Via Saideno 17, Galbiate, 23851, IT)
POZZI, Fabio (Via ai Colli 1A, Calolziocorte, 23801, IT)
FALCIOLA, Dino (Via Principe di Piemonte 4, Stresa, 28838, IT)
Application Number:
IB2016/051826
Publication Date:
October 06, 2016
Filing Date:
March 31, 2016
Export Citation:
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Assignee:
CASTFUTURA S.P.A. (Via Baccanello 1/B, Terno d'Isola, 24030, IT)
International Classes:
G01K1/14; G01K7/02
Domestic Patent References:
WO2013021341A22013-02-14
Foreign References:
US20090133449A12009-05-28
US20130195144A12013-08-01
Attorney, Agent or Firm:
KARAGHIOSOFF, A. Giorgio (Via F. Baracca 1R, Savona, 17100, IT)
Download PDF:
Claims:
CLAIMS

1. Thermocouple comprising:

a temperature sensor (10) having a measuring end (13) intended to be exposed to a heat source and an end for an output electrical signal variable as a function of the temperature to which the measuring end (13) has been exposed;

a supporting body (1) for said temperature sensor (10) and which supporting body (1) has fastening means intended to cooperate with the structure (2) of a use unit,

characterized in that

the supporting body (1) has at least one appendage (401) fastening, by a press snap fit (601) , into a corresponding snap seat (102) ,

said fastening appendage being provided with one or more protuberances projecting outwardly therefrom and cooperating with an inner wall of the snap seat by at least one tip scraping or scoring said inner wall of the snap seat and provided on said one or more protuberances .

2. Thermocouple according to claim 1, wherein said fastening appendage (401) is intended to be inserted into a corresponding hole (102) of the structure (2) of a use unit and it has radial enlargements (3) with respect to the direction fitting into said hole (102) which are insertion stop abutment surfaces intended to cooperate with the wall delimiting said hole (102) and at least one portion provided adjacent to said abutment surfaces on the side faced towards said hole (102) , which portion has at least one enlargement (601) of the transverse section from the one substantially identical to or slightly smaller than the orifice of the hole (102) to a dimension slightly greater than the inner orifice of the hole (102) , which enlargement (601) is at least deformable by pressing it upon the insertion of the appendage into the hole and it bears one or more of said tips .

3. Thermocouple according to claim 1 or 2, wherein the material of the enlargement (601) has a higher hardness than the material of the structure (2) where the hole (102) is provided.

4. Thermocouple according to one or more of the preceding claims, wherein the supporting body (1) is composed of a bushing or a portion of a cylindrical tube wherein the temperature sensor (10) is fastened and which cylindrical bushing or which portion of cylindrical tube have a radial enlargement (3) forming an insertion stop abutment and which is provided in a predetermined axial position with respect to the end (13) of the temperature sensor (10) intended to be exposed to the heat source and at least one protuberance (601) projecting radially outwardly with respect to the shell surface of said cylindrical bushing or of said portion of cylindrical tube (401) said protuberance (601) being inelastically deformable by pressing the supporting body (1) into the hole (2) , by the wall of the hole and said protuberance being provided in a circumferential strip of the bushing or of the tube (401) adjacent to the radial enlargement (3) on the side thereof opposite to the end of the thermocouple (10) intended to be exposed to the heat source .

5. Thermocouple according to one or more of the preceding claims, wherein the at least one protuberance (601) can be brought by a part (701) of the wall of the cylindrical bushing or of the portion of cylindrical tube (401) which is flexible and deformable radially inwardly.

6. Thermocouple according to one or more of the preceding claims, wherein there is provided a plurality of protuberances (601) placed angularly arranged on one or more circumferential strips of the bushing or of the portion of tube (401) which are in a position coincident with the axial extension of the wall delimiting the hole (102) .

7. Thermocouple according to one or more of the preceding claims , wherein the protuberances are generated by a ridged or corrugated configuration of the circumferential strip of the bushing or of the portion of tube (401) coincident with the thickness of the wall delimiting the hole (102) with the bushing or tube in the assembled condition.

8. Thermocouple according to one or more of the preceding claims , wherein the protuberance or protuberances (601) are made with the shape of a asymmetric tooth oriented in the axial direction and having the less steep side with respect to the axial direction of the bushing or tube portion.

9. Thermocouple according to one or more of the preceding claims, wherein the position of the sensitive end of the thermocouple from the heat source, is variable by means of an insertion stop abutment radial enlargement whose position in relation to the sensitive end of the thermocouple is variable.

10. Thermocouple according to one or more of the preceding claims, wherein the supporting body (1), that is the bushing or the tube portion are made of sheet metal, for example sheet metal made of steel by molding a flat sheet metal and by rolling it in a cylindrical shape .

11. Thermocouple wherein the temperature sensor is composed of :

at least a first conductor element (11) and at least one second conductor element (12) , which first and second conductor elements are brought in electrically conductive contact at one detecting end (13) , so called hot junction, such to generate at the two free ends of each conductor element (11) and (12) a potential difference that is a function of the temperature detected at the detecting end;

said first conductor element being in the form of a tubular element wherein the second conductor element is coaxially fitted and said first conductor element being tightened against the external shell surface of said second conductor element (12) for an end portion of a specific length (13) , the supporting body (1) being fastened to said first conductor element (11) by a radial tightening against the external surface of said first conductor element (11) or by rolling the molded sheet metal forming said supporting body (1) about said first tubular conductor element (11) .

12. Thermocouple according to one or more of the preceding claims, wherein the supporting body (1) is composed of a supporting tube having a constant inner diameter and a predetermined length, and wherein one end is fitted with the pair (11, 12) of conductors of the thermocouple which is fastened in place by welding and/or compression, while on the supporting tube in a predetermined axial position with respect to the length of said supporting tube at least one fastening bushing is fitted, which is removable and lockable by snap- action in a preventive coupling position, which fastening bushing bears the members (601) for a snap press fit into a corresponding snap seat (102) ,

said fastening bushing (401') being provided with inner radial teeth (1001) arranged at least along the head edges of said fastening bushing (401'), which teeth have such a length to tighten the supporting tube therebetween in the condition fitting the fastening bushing (401') and supporting tube (102) assembly in the snap seat (102) .

13. Thermocouple according to claim 12, characterized in that along the supporting tube there are provided one or more outer radial annular shoulders (111, 211, 311) at predetermined axial distances proportioned to the axial extension of the fastening bushing (401') and/or of a radial enlargement ring (3) .

14. Thermocouple according to claim 13, wherein said shoulders are made by axially pressing the supporting tube (1) .

15. Thermocouple use unit, such as for example a burner or a heat source of another type and which is provided with at least one cock regulating the supply of fuel gas or another fuel, which cock has a solenoid valve controlled by the electrical signal generated by said thermocouple, which use unit has a fastening seat (102) for said thermocouple, and which fastening seat is shaped in such a manner to or has such fastening means to cooperate with the fastening means of the supporting body of said thermocouple, said thermocouple being made according to one or more of the preceding claims .

16. Fastening method for a thermocouple, which method provides the steps of fastening the thermocouple to a fastening body having a fastening appendage intended to be fitted into a fastening hole;

Providing a fastening hole with an orifice corresponding to the transverse section of the fastening appendage with reference to the direction of insertion of the appendage into said hole;

Providing a specific axial length of the wall delimiting the hole;

Providing the fastening appendage with insertion stop abutment transverse surfaces provided in a predetermined position of the extension of said appendage in the direction of insertion;

Providing enlargements of the transverse section of said appendage with a dimension slightly greater than the orifice of said hole and in a position adjacent to the insertion stop abutment surfaces to such an extent that in said insertion stop position said enlargements are coincident with the wall delimiting the hole;

Providing said enlargements to be inelastically deformable or mounted on wall parts inwardly radially flexible, such to generate a press snap fit of said supporting body within said hole;

Providing for at least a part of the enlargements at least one tip scraping or scoring the inner wall of the hole that, in the snap condition, scrape, score or grip said inner wall of said hole.

Description:
Thermocouple and method for fastening the same.

The present invention relates to a thermocouple comprising:

a temperature sensor having a measuring end intended to be exposed to a heat source and an end for an output electrical signal variable as a function of the temperature to which the measuring end has been exposed;

a supporting body for said temperature sensor and which supporting body has fastening means intended to cooperate with the structure of a use unit.

In one embodiment the invention particularly relates to a thermocouple composed of :

at least a first conductor element and at least a second conductor element, which first and second conductor elements are brought in electrically conductive contact at one detection end, so called hot junction, obtained by joining an end of the first conductor element with a corresponding end of the second conductor element, such to generate at the two free ends of each conductor element, a potential difference that is a function of the temperature detected at the detecting end;

a supporting body wherein said at least two conductor elements are mounted and which supporting body has fastening means intended to cooperate with the structure of a use unit.

The invention relates also to a use unit for such thermocouple, such as for example a burner or a heat source of another type and which is provided with at least one cock regulating the supply of fuel gas or another fuel, which cock has a solenoid valve controlled by the electrical signal generated by said thermocouple, which use unit has a fastening seat for said thermocouple, and which fastening seat is shaped in such a manner to or has such fastening means to cooperate with the fastening means of the supporting body of said thermocouple.

In one preferred embodiment at least a part of the use unit and specially the part where the fastening seat for the thermocouple is provided is made of aluminium.

This type of thermocouples and use units to which said types of thermocouples are associated, are known.

In known thermocouples, the supporting body is composed of a cylindrical element fastened into a hole or slot or a seat of the structure of a use unit or of an intermediate mounting element by means of screw tightening means or by elastic clamps or locking clips.

The supporting body for the thermocouple can have only a supporting and merely mechanical fastening function, therefore said body is electrically insulated from the conductors and from the metal components forming the thermocouple and contribute in generating the signal, and it can have also the function of electrically connecting one of the at least two conductors forming the thermocouple, generally the ground potential. In this case, one of the conductors forming the thermocouple is connected even electrically to the supporting body.

There are several variants of such known arrangements all aiming at guaranteeing a good mechanical fastening and, if provided, also a good electrical connection.

In thermocouples called as single-wire thermocouples , only one of the two conductor elements is connected by an electric wire to the corresponding input of the electromagnet of the solenoid valve, while the other conductor element forming the thermocouple is connected to the ground end of the electromagnet through the metal structure of the use unit.

In double-wire thermocouples the two ends of the electromagnet are connected to one of the two conductor elements of the thermocouple respectively though a corresponding electric wire.

In both cases , a variant provides the supporting body to be fastened into a hole completely peripherally closed or opened on one side. In this case the supporting body has a shoulder abutting against the peripheral surface delimiting the hole and means fastening it in the engaged position in the hole, such as for example screw locking means. These can be composed of a threaded end of the supporting body on which a nut screw is tightened, the wall with the hole provided therein being tightened between the abutment shoulder and the nut screw.

On the contrary alternative arrangements of the abutment shoulder provide the supporting body to be threaded for a substantial length thereof, such that the threaded portion protrudes from the two sides of the hole and the abutment shoulder to be also composed of a nut screw.

On the contrary other embodiments provide snap grooves for clips or clamps that form a shoulder respectively on both the sides of the wall providing the hole engaging the supporting body.

Other fastening methods provide the thermocouple to be secured into a seat with a corresponding shape by means of a collar, which collar is provided on a mounting that is an intermediate element for the fastening to the structure of the use unit.

The drawback of known supporting bodies and of methods for fastening the thermocouples is the fact that the supporting bodies are made of brass and need expensive treatments for removing shaving. This prevents cycles for manufacturing the supporting bodies from being rapid and from guaranteeing also a given flexibility in adapting them to different types of thermocouples and a given flexibility in using them.

Particularly in household appliance field, as cheap cooking hobs, ovens or possibly also gas boilers or the like, it is necessary to reduce both manufacturing costs and assembling costs.

Moreover when using a single-wire solution and the structure of the use unit where the seat for fastening the thermocouple is made of aluminium, the known systems for fastening the thermocouples do not guarantee the electrical contact between thermocouple body and the material of the structure of the use unit.

This is due to the fact that the mere screw tightening or the fastening by clips or clamps do not guarantee to remove the layer of naturally forming aluminium oxide which is electrically insulating, therefore poor contacts affecting the proper operation of the solenoid valve can be generated.

Therefore the invention aims at improving current thermocouples as regards the means for fastening them to the structures of use units such to overcome the drawbacks of the current thermocouples .

Moreover the invention aims at improving the current thermocouples such to guarantee an optimal fastening thereof and a constructional structure allowing flexible and cheap process to be used for manufacturing the thermocouples and the supporting bodies .

The invention achieves the above objects by providing a thermocouple of the type described hereinbefore, wherein the supporting body has at least one appendage fastening, by a press snap fit, into a corresponding snap seat, said fastening appendage being provided with one or more protuberances projecting outwardly therefrom and cooperating with an inner wall of the snap seat by at least one tip scraping or scoring said inner wall of the snap seat and provided on said one or more protuberances .

In one embodiment said fastening appendage is intended to be inserted into a corresponding hole of the structure of a use unit which hole is the snap seat and has a predetermined inner diameter and a predetermined axial length, while said appendage has side enlargements with respect to the direction fitting into said hole which enlargements are insertion stop abutment surfaces intended to cooperate with the wall delimiting said hole and at least one portion provided adjacent to said abutment surfaces on the side faced towards said hole, which portion has at least one enlargement of the transverse section from the one substantially identical to or slightly smaller than the orifice of the hole to a dimension slightly greater than the inner orifice of the hole, which enlargement is at least deformable by pressing it upon the insertion of the appendage into the hole and which enlargement bears the scraping or scoring tip or tips.

One preferred embodiment provides the supporting body of the thermocouple to be composed of a bushing or a portion of a cylindrical tube wherein the thermocouple is fastened and which cylindrical bushing or which portion of cylindrical tube have a radial enlargement forming an insertion stop abutment and which is provided in a predetermined axial position with respect to the end of the thermocouple intended to be exposed to the heat source and at least one protuberance projecting radially outwardly with respect to the shell surface of said cylindrical bushing or of said portion of cylindrical tube said protuberance being inelastically deformable by pressing the supporting body into the hole, by the wall of the hole and said protuberance being provided in a circum erential strip of the bushing or of the tube adjacent to the radial enlargement on the side thereof opposite to the end of the thermocouple intended to be exposed to the heat source .

According to a further characteristic that can be provided separately from or in combination with the ring being inelastically deformable, the protuberance can be brought by a part of the wall of the cylindrical bushing or of the portion of cylindrical tube which is flexible and deformable radially inwardly.

Advantageously it is possible to provide a plurality of protuberances placed angularly arranged on one or more circumferential strips of the bushing or of the portion of tube which are in a position coincident with the axial extension of the wall delimiting the hole .

A variant provides the protuberances to be generated by a ridged or corrugated configuration of the circumferential strip of the bushing or of the portion of tube coincident with the thickness of the wall delimiting the snap seat and particularly the hole with the bushing in the assembled condition.

When such corrugated configuration provides a section with projections having a sharp pattern, for example like a curved and closed zig-zag line, then the scoring effect is also provided as in the embodiment with one or more teeth.

It is also possible for such circumferential strip where the wall of the bushing or of the tube portion are ridged or have a corrugated pattern to be provided with such a conical arrangement to generate a progressive increase in the diameter towards the radial stop abutment enlargement.

Still according to an improvement, the protuberance or protuberances are made with the shape of a asymmetric tooth having the side less steep with respect to the axial direction of the bushing or tube portion .

Advantageously at least the protuberance or protuberances and particularly the tooth or teeth, preferably the whole supporting body are made of a material having a hardness higher than that of aluminium or similar metals and that therefore score the surface of the wall delimiting the receiving hole during the press snap fit of the thermocouple into said hole of the structure of the use unit.

A further advantage of the snap fit of the thermocouple is that it is not only locked as regards an axial movement, that is in the direction fitting or removing it from the seat, but also as regards a rotation .

This is particularly advantageous in comparison with thermocouples according to prior art, since the rotation is the movement that is more efficacious in breaking the conductors and the junctions thereof, both of the pressing mechanical type and by welding or brazing .

A preferred embodiment provides one or more protuberances to be provided each one on a flexible tab formed by a part of the shell wall of the bushing or of the tube portion separated from the remaining part of the wall by at least two or more cuts forming a separation polygonal line and that leave a material bridge to the remaining part.

In single-wire thermocouples when the supporting body is a conductor for connection of one of the conductor elements forming the thermocouple, the score or scratch made by the tip or tips of the protuberances and particularly by the tooth or teeth penetrate into the metal of the seat obtained in the structure of the use unit, crossing or removing away the layer of aluminium oxide and therefore establishing a good electric contact.

In order to guarantee an optimal electric conduction between the supporting body and one of the two conductor elements forming the thermocouple, preferably, but not exclusively made of nickel chrome, said conductor element is connected to the supporting body by welding, particularly laser welding.

On the contrary, in two-wire thermocouples, the supporting body at its end opposite to the one fastening to the thermocouple, has a terminal for the connection to an electric conductor that generally is designed to be connected to the ground potential .

As regards the possibility of changing the position of the sensitive end of the thermocouple from the heat source, it is possible to provide an insertion stop abutment radial enlargement whose position in relation to the sensitive end of the thermocouple is variable. This can be obtained in different manners, such as for example by providing a series of tabs obtained by cuts of the wall of the bushing or of the tube, similarly to tabs carrying the protuberances or teeth and arranged along different circumferential strips of the bushing or of the tube portion, which strips have different distances from the sensitive end of the thermocouple. Depending on the provided position the tabs having the corresponding distance from said thermocouple sensitive end are bent outwardly.

As an alternative a stop abutment radial enlargement can be obtained by simply making it as an annular radial enlargement composed of a metal ring having an inner diameter slightly lower than the outer diameter of the bushing or of the tube portion, said bushing or tube portion being shaped such to form one or more annular circumferential grooves along the outer shell wall whose diameter substantially corresponds to the inner diameter of the ring, said grooves being arranged side-by-side at different axial distances from the sensitive end of the thermocouple, that is from the end intended to be exposed to the heat source, said ring being moved by an elastic compression at the provided groove at a predetermined distance.

A preferred alternative for the coupling of the ring forming the stop abutment radial enlargement, provides the ring to have an inner diameter substantially equal to the outer diameter of the supporting body, at least at the fastening area and said ring to be fitted on the supporting body, to be axially slid up to the proper position and then axially pressed. By the axial compression, the ring gets deformed also in a radial direction reducing the inner diameter and therefore generating a radial narrowing that is pushed by a given pressure against the outer shell surface of the supporting body.

Such solution can be provided in combination with or without the supporting body having the annular circumferential groove along the outer shell wall. If at least one groove is provided, the axial compression causes the material generating the reduction in the inner diameter of the ring to penetrate into the groove generating a mutual engagement between the ring and the supporting body that prevents the ring from axially sliding. This is important since when the supporting body is mounted by being snap-fitted in the mounting seat by an axial compression, the coupling between the ring and the supporting body with respect to the mutual axial movement has to withstand the compression forces acting on the supporting body for snap-pressing it in the seat.

According to a further improvement, particularly suitable for a supporting body made as a tube or bushing made of a sheet metal, it is possible to fasten the ring by providing it to have an inner diameter corresponding to the outer diameter of the tubular body, at least in the coupling area and with a predetermined dimensional accuracy and by providing that after the ring has been brought in the proper position with respect to the supporting body, the two parts are fastened with each other by welding, particularly laser welding.

A preferred embodiment provides the bushing or the tube portion to be made of sheet metal, for example sheet metal made of steel .

In this case the manufacturing is very simple and cheap since it is possible to form the bushing or tube portion by molding a flat sheet metal and by rolling it.

Moreover the fastening of the thermocouple inside the supporting body can occur very simply upon the rolling of the pre-shaped sheet metal or in a following step radially pressing the tube or bushing on the thermocouple .

This solution is particularly advantageous when it is provided in combination with a thermocouple composed of at least two conductors, one of which forming an outer cylindrical cap that at one end thereof is clamped on a coaxial second conductor with a smaller diameter by a conical narrowing and an end portion with a smaller diameter by means of which said cap element is in direct contact with the second inner conductor.

In this case the bushing or tube portion have at least one end section tightening against the end with greater diameter of the cap element, which tightening determines both the mechanical and electrical connection .

It is clear that it is very easy to modify the mold such to have an arrangement of the supporting body of the type suitable for the single-wire thermocouple and of the type suitable for the two-wire thermocouple.

Also as regards the position of the stop abutment it is possible to provide to rapidly change the mold for forming the groove engaging the ring forming the stop abutment radial shoulder in a predetermined position corresponding to the one necessary for assembling the thermocouple on a specific use unit.

The change in the production line depending on the use unit to which the thermocouple is dedicated is rapid and cheap and it prevents a great amount of different constructional parts from being kept in stock for the different assembling options.

Still according to a further embodiment of the invention, in combination with the above thermocouple a mounting hammer is provided for press snap fitting in the seat, which hammer comprises a head coupling with a cavity intended to house the sensitive end of the thermocouple and to abut against the surface facing such end of the stop radial abutment enlargement.

From the above also a fastening method for a thermocouple is clear, which method provides the steps of fastening the thermocouple to a fastening body having a fastening appendage intended to be fitted in a fastening hole;

Providing a fastening hole with an orifice corresponding to the transverse section of the fastening appendage with reference to the direction of insertion of said appendage into said hole;

Providing a specific axial length of the wall delimiting the hole; Providing the fastening appendage with insertion stop abutment transverse surfaces provided in a predetermined position of the extension of said appendage in the direction of insertion;

Providing enlargements of the transverse section of said appendage with a dimension slightly greater than the orifice of said hole and in a position adjacent to the insertion stop abutment surfaces to such an extent that in said insertion stop position said enlargements are coincident with the wall delimiting the hole;

Providing said enlargements to be inelastically deformable or mounted on wall parts inwardly radially flexible, such to generate a press snap fit of said supporting body within said hole.

According to a further variant embodiment, the supporting body and the snap fastening appendage are made as one piece from the same sheet metal .

A variant embodiment provides the supporting body and the snap fastening appendage to be composed of two separate parts snap connectable with each other, the fastening body being in the form of a supporting tube having a predetermined length and a predetermined inner and outer diameter and the fastening appendage being composed of a bushing engageable by snapping it in a condition fitted on the supporting tube in a predetermined position with respect to the ends of the supporting tube.

The fastening bushing can have the same members for snap engagement with the seat described above and in the different combinations described above.

The inner diameter of the fastening body substantially corresponds to the outer diameter of the outer tubular conductor of the thermocouple, while the outer diameter substantially corresponds to the inner diameter of the bushing.

Advantageously the supporting tube has continuous or discontinuous annular radial shoulders forming abutments for axially holding the fastening bushing.

Advantageously the fastening bushing has an inner diameter greater than that of the supporting tube and at the head ends it has a crown of radial teeth inwardly projecting that reduce the passage orifice to a diameter smaller than that of the outer radial protuberances of the supporting tube and allow said tabs to overcome said outer radial shoulders of the supporting tube by the inherent elastic deformability of said tabs .

According to a further improvement, the tabs have such a radial length that, in the condition with the supporting tube and fastening bushing assembly snap fitted into the corresponding seat, these tabs are pressed against the shell wall of the supporting tube by a predetermined tightening pressure, by locking in position the supporting tube with respect to the fastening bushing.

The annular shoulders axially holding the fastening bushing can be made, with the bushing mounted on the supporting tube or before mounting the bushing on the supporting tube, by axially pressing the supporting tube into an inner and outer radial containment mold.

Also the insertion stop radial abutment enlargement for the supporting body into the seat of the use unit can be in the form of a ring fastened to the supporting tube similarly to the several variants described above.

A preferred embodiment for such variant provides the radial enlargement ring to be tightened between two outer annular shoulders of the supporting tube obtained by axially pressing said tube and forming axial abutments at the two faces of the radial enlargement ring .

With respect to the embodiment providing the fastening appendage to be integrated with the supporting body, such variant that provides the supporting body to be made as a simple tube cut to size made of steel, allows the supporting body to be adapted very fast and simply to the different formal and dimensional specifications required by the contingent case by means of simple steps of axial compression for forming the annular shoulders.

Once the type of burner and the configuration and position of the seat of the thermocouple are determined, it is possible to simple cut to size a length of the supporting tube, to provide such a position of the fastening bushing along said supporting tube that the latter coincides with the axial length, of the snap seat, to make by a controlled axial compression the outer annular radial shoulders corresponding to the positions provided for the fastening bushing and for the radial enlargement ring for the insertion stop abutment of the thermocouple, to fit in the proper end of the supporting tube the thermocouple and weld it to the supporting tube and the thermocouple is substantially mounted in a supporting body that is specifically suitable for a predetermined snap seat and a predetermined burner, all without providing special parts in stock that are dedicated only to specific types of burner or use device.

These and other characteristics and advantages of the present invention will be more clear from the following description of some embodiments shown in the annexed drawings wherein:

Figure 1 is a perspective view of the thermocouple of the present invention in the embodiment used for a two-wire thermocouple;

Figure 2 is the thermocouple of figure 1 according to a view line different than that of figure 1;

figure 3 is a section according to a diametral/axial plane of the thermocouple of the present invention;

Figure 4 is an exploded perspective view;

Figure 5 is an enlarged detail of the supporting body of the thermocouple according to previous figures;

Figure 6 is a schematic view of the thermocouple press fitted in a hole of a structure of a use unit.

Figure 7 is a perspective view of a second embodiment of a thermocouple and of the corresponding supporting body. Figure 8 is an exploded view of the variant of figure 7.

Figure 9 is a thermocouple mounted in a burner body.

Figures 10 and 11 are two perspective views on one of the two head sides respectively of a fastening bushing according to variant of figures 7 to 9;

Figure 12 is a sectional view according to a diametral axial plane of the thermocouple and of the supporting body according to the variant of figures 7 to 11.

It is specified that in the figures annexed to the present patent application some possible embodiments are shown, but such embodiments have to be intended only for illustrative purposes and not as a limitation of the inventive concept of the present invention that is to provide a thermocouple and its components, such to overcome the drawbacks of the current thermocouples by making the assembling more rapid and easy, improving the electric conduction between the body of the thermocouple and the seat for fastening it to the structure of the use unit, for the single-wire arrangements and particularly when the structure of the use unit is made of aluminium, and while reducing manufacturing costs.

The shown embodiment is about a two-wire thermocouple, however for the person skilled in the art it will be immediately clear which variants can be applied for a single-wire thermocouple.

Moreover the particular type of thermocouple shown and described has not to be intended as a limitation of the inventive concept, but only as a solution given by way of example.

Particularly and with reference to figure 4, the thermocouple of the present invention comprises a first conductor element 11 made of a first metal and a second conductor element 12 composed of a rod-like element made of a second metal. The two conductor elements 11 and 12 are brought in electrically conductive contact at one heat detection end 13 obtained by joining an end of the first conductor element 11 with a corresponding end of the second conductor element 12 , such to generate at the two free ends of each conductor element, a potential difference that is a function of the temperature detected at the detecting end.

The conductor element 12 is assembled coaxial with the conductor element 11 that forms an outer tubular cap conically tapering towards the end 13 where it is secured to the conductor element 12 and possibly also welded at the head end of said two conductors.

The free end of the second conductor element 12 opposite to end connecting at end 13 with the first conductor element 11 is connected to a corresponding transmission conductor 22, covered by an electric insulating and protective sheath.

The tubular conductor element 11 is assembled by being tightened into a supporting body 1 intended to support the thermocouple in a fastening seat denoted in figure 6 by 102 provided in the structure of a use unit (not shown) . The conductor elements can be made of different metals. Particularly the outer conductor element 11 can be made of nickel chrome.

According to an improvement the conductor element 11 is fastened to the supporting body 1 by welding, particularly laser welding. This guarantees an efficacious electrically conductive contact between the conductor element 11 and the tubular body 1.

Particularly said structure is composed of a wall, a tab or the like wherein a housing is provided with a shape complementary to at least one fastening appendage of the supporting body 1.

Said housing 102 can be a hole, even open on the side and the fastening appendage of the body 1 is composed of a bushing or a tube portion intended to be fitted in said hole.

The structure can be that of a cock supplying gas or other fuel, a support surface for a burner or the fastening structure of the burner or an appendage of the burner body or similar parts.

Such as shown in figures 1 to 6 of such first variant embodiment, the supporting body 1 has the shape of a tube portion having a predetermined diameter, greater than that of the first conductor element 11 and against an end portion of the first conductor element 11 the corresponding end portion 101 of the supporting body 1 is mechanically tightened by forming a conical narrowing 201 and contemporaneously generating an electric connection between the conductor element 11 and the supporting body 1. At the end opposite to the fastening end for the thermocouple 10, the supporting body 1 has a terminal 301 fastening a transmission conductor 21 intended, like the conductor 22, to be connected to a corresponding inlet of the electromagnet of a solenoid valve provided in the gas regulating cock or the like.

As it results from figures in a certain axial position with respect to the sensitive end 13 of the thermocouple, that is the end intended to be exposed to the heat source, the body 1 has an outer annular radial enlargement 3 forming an insertion stop abutment thereof into the hole 102 of the structure 2 of the use unit (fig .6) .

Advantageously, as it results from figure 5, the annular stop abutment shoulder 3 is composed of a ring or a washer engaged by being elastically pressed into a groove 501 provided in the shell wall 401 of the body 1. The inner diameter of the ring or washer is slightly smaller than the outer diameter of the body 1 in the cylindrical portion 401 and substantially corresponding to the outer diameter of the groove 501.

Advantageously it is preferred also for the width of the groove 501 to substantially correspond to the axial thickness of the ring or washer.

In an annular strip adjacent to the stop abutment annular shoulder 3 there is provided a crown of three pairs of teeth 601. The teeth 601 of each pair are axially aligned and radially protrude outwardly from the outer surface of the portion 401 of the supporting body 1. Each tooth 601 has a saw tooth shape with the less steep side oriented forwards with respect to the direction of insertion of the supporting body 1 into the hole 102 of the structure 2 of the use unit.

Each tooth 601 is further carried at the free end of a corresponding tab 701.

Teeth 601 have each one a scraping and/or scoring tip intended to cooperate in the condition pressed into the snap seat, that is the hole 102, with the wall of said hole by gripping or scoring it.

The tab is formed of a part of the same shell wall of the tubular body 1 separated from the remaining part by cuts 801, 901.

When, as in the shown embodiment, the tabs extend in the circumferential direction of the supporting body 1, two cuts 801 are oriented in the circumferential direction and one cut 901 connecting the first two cuts is oriented in the axial direction.

Obviously it is possible to provide only one tooth instead of pairs of teeth 601 or also groups of several teeth. It is also possible to provide the teeth of the individual circumferential strips to be angularly staggered with respect to each other.

Teeth are an exemplary embodiment and have not to be intended as a limitation of the several possible options for the arrangement of the outer radial protuberances .

As an alternative the wall of the supporting body 1 can also be ridged or provided with a corrugated or zig-zag pattern such to form rounded or sharp protuberances and such to have a radial deformability . The corrugated, zig-zag or ridged surfaces can be provided on the tabs 701.

Said corrugated, zig-zag or ridged surfaces act also for scraping, scoring or penetrating the surface of the wall of the snap seat, that is the hole 102.

Teeth 601 or the protuberances formed according to a possible functionally equivalent alternative have such a protrusion that their tips fall on a circumference with a diameter slightly greater than that of the hole 102 (fig.6).

Here as shown in figure 6 upon the snap press fit, due to the deformability of the material of teeth 601 or of the wall of the hole 102 and/or the flexibility of the tabs 701, the tubular body is fitted into the hole 102, in the position where the annular stop abutment shoulder contacts the faced surface of the wall delimiting the hole 102.

As it results from figure 6 when the metal material of the tubular body 1 or only of the teeth 601 has a hardness higher than the material of the structure 2 where the hole 102 is provided, then teeth score also partially the wall delimiting the hole 102. This is particularly advantageous when in a single-wire thermocouple the ground contact has to be made through the tubular body 1 and the structure of the use unit. Particularly the advantage is considerable when the hole 102 is obtained into an aluminium structure. In this case the teeth 601 that score the aluminium wall allow the layer of aluminium oxide, which is not electrically conductive, to be crossed and therefore malfunctions are avoided.

Moreover the fact that teeth can grip the material by scoring it makes the mechanical locking safe both with reference to an axial movement and a rotation. This is particularly advantageous since the rotation of the thermocouple is particularly effective in causing the electric connections and conductors to be mechanically broken.

From figure 6 it is clear that instead of only two circumferential crowns of teeth three of them have been provided by splitting into two teeth the tooth axially nearer to the end of the thermocouple to be exposed to the heat source .

With reference to figure 5, when the thermocouple should be used in different assembling conditions with reference to the distance of the end 13 from the heat source, then instead of only one groove 501 it is possible to provide one or more annular grooves arranged at different axial distances from the end 13 of the thermocouple.

It is also clear, as already described in the introduction, that it is possible to provide different alternatives for fastening the ring 3 to the body 1 that do not provide it to be pressed, such as for example the axial compression of the ring that causes the inner diameter to be reduced and therefore the material of said ring to penetrate into the corresponding fitting groove. As an alternative or in combination the ring can have an inner diameter exactly corresponding to that of the body 1 and it can be welded to said body, particularly by laser welding.

The transmission conductor 21 and/or the transmission conductor 22 can be made of any metal known in prior art, such as for example copper but according to a preferred embodiment they can be made of aluminium.

With reference to a possible variant intended for a single-wire thermocouple, here the tubular body does not have a fastening terminal 301 for fastening a transmission conductor 21, but the connection occurs by the structure 2 of the use unit.

As it is clear the supporting body 1 can be easily made by molding it from a flat sheet metal and then by rolling and tightening it on the outer conductor element 11 of the thermocouple.

By arranging several molds it is possible to easily match the configuration of the supporting body to the assembling conditions specific for a given application, and therefore compared with the use of conventional mounting bodies, the invention allows the supporting body to be manufactured more quickly and not to have in stock a great amount of different supporting bodies for the different assembling conditions.

Moreover the construction by means of molding and rolling operations is cheaper than the construction by a shaving removing treatment.

The present invention is particularly suitable in combination with conductor elements made of aluminium that have problems related to a resistance to repeated torsions: the snap press mechanical locking keeps the thermocouple absolutely fixed against any type of roto- translation movements, which is not possible in known thermocouples at least as regards the rotation thereof.

Therefore such construction not only eliminate costs and makes supporting body-related mounting operations more rapid, but it allows an effective and safe use of the aluminium as a conductor wire eliminating at a great extent some drawbacks due to the mechanical brittleness of the material.

With reference to the variant embodiment shown in figures 7 to 12, in these figures the same reference numerals are used as in figures 1 to 6 for like parts or for parts having like functions.

In such variant embodiment, the supporting body 1 is in the form of a cylindrical tube having a predetermined axial length and an inner diameter substantially identical to or slightly greater than the outer diameter of the tubular conductor element 11 of the thermocouple.

Unlike the previous version, since the fastening appendage is not made as one piece, the supporting body has a diameter constant for all its length and it can be obtained by cutting to size a tube portion.

The tubular body 1 is fitted on the conductor element 11 of the thermocouple and the two parts are preferably welded together and particularly welding is a laser welding.

Along the tubular body 1 there are provided different outer radial annular shoulders 111, 211, 311 that are axial delimitations of sections of tube 1 where a radial enlargement ring 3 and a fastening bushing 401' are respectively held.

Such bushing 401' like the examples of the previous variant embodiment has a crown of three pairs of teeth 601.

Teeth 601 of each pair are axially aligned and radially project outwardly from the outer surface of the portion 401 of the supporting body 1. Each tooth 601 has a saw tooth shape with the less steep side oriented forwards with reference to the direction of insertion of the supporting body 1 into the hole 102 of the structure 2 of the use unit.

Each tooth 601 is further carried at the free end of a corresponding tab 701.

Teeth 601 have each one a scraping and/or scoring tip intended to cooperate in the condition pressed into the snap seat, that is the hole 102, with the wall of said hole by gripping or scoring it.

The tab is formed of a part of the same shell wall of the tubular body 1 separated from the remaining part by cuts 801, 901.

When, as in the shown embodiment, the tabs extend in the circumferential direction of the supporting body 1, two cuts 801 are oriented in the circumferential direction and one cut 901 connecting the first two cuts is oriented in the axial direction.

Obviously it is possible to provide only one tooth instead of pairs of teeth 601 or also groups of several teeth. It is also possible to provide the teeth of the individual circumferential strips to be angularly staggered with respect to each other.

Teeth are an exemplary embodiment and have not to be intended as a limitation of the several possible options for the arrangement of the outer radial protuberances .

As an alternative the wall of the supporting body 1 can also be ridged or provided with a corrugated or zig-zag pattern such to form rounded or sharp protuberances and such to have a radial deformability .

The corrugated, zig-zag or ridged surfaces can be provided on the tabs 701.

Said corrugated, zig-zag or ridged surfaces act also for scraping, scoring or penetrating the surface of the wall of the snap seat, that is the hole 102.

Teeth 601 or protuberances formed according to a possible functionally equivalent alternative have such a protrusion that their tips fall on a circumference with a diameter slightly greater than that of the hole 102.

As it results particularly from the combination of figures 10, 11 and 12 the fastening bushing 401' is axially held between two annular shoulders 111 and 211, while the ring 3 is held between the annular shoulder 211 and a further annular shoulder 311.

The bushing 401' has an outer diameter proportioned to the diameter of the snap hole and at the head ends it has a crown of radial inner teeth or a given number of radial inner teeth arranged along the perimeter which inner radial teeth 1001 have a given radial length and end at such an inner diameter that by their elasticity they can overcome the annular shoulder 111 thus retaining the bushing coupled to the tube 1 in the proper axial position.

The inner and outer diameters of the bushing 401' and of the tubular body 1 have such a dimension that, in the condition fitted into the snap seat 102, the fastening bushing 401' remains pressed between the wall of the snap seat, that is the hole 102, and the outer wall of the tube 1 against which the inner radial tabs 1001 are pressed as it is clear from the section of figure 12.

Figure 9 shows the body of a burner 2' having a hole 102 in an outer radial extension a thermocouple being fitted into such hole 102 according to the variant of figures 7 to 12. However such condition can be applied also to the variant of figures 1 to 6. The difference simply is that since the fastening bushing 401' is not integrated in this variant it is not necessary to provide a conical enlargement 201, but the whole tubular body has the same inner and outer diameter that in the variant of figures 1 to 6 has the portion 101 fastening to the conductor element 11 of the thermocouple.

As regards the annular shoulders on the tubular body, these can be formed by an axial compression of the supporting tube 1.

It is possible to provide molds and counter-molds allowing the tube wall to be deformed only outwardly, preventing it from collapsing inwardly, such as for example a core inserted in the tube and walls containing the outer radial deformation of the tube wall that allows outer, radial annular shoulders with different radii to be formed.

An alternative can provide pliers clamping the tube at different axial distances from each other associated with a core inside the tube that prevents it from collapsing inwardly and that exert a compression of the material in the axial direction of the tube.

A part of such outer radial annular shoulders can be made before assembling on the tube 1 the ring 3 and/or the fastening bushing 401' and/or a part also after said assembling.

The advantage of such embodiment is the fact of saving further material, in comparison to the embodiment of figures 1 to 6, making more easy and more rapid to adapt the different conditions for assembling the thermocouples on different types of burners.

In order to adapt a supporting body to a specific assembling condition of the thermocouple that is to a specific assembling seat on a burner or another use unit it is only necessary to:

cut to size the tube;

forming at least a part of the annular shoulders; assembling the radial enlargement ring 3 and the fastening bushing 401' on the tube;

possibly forming the further annular shoulders; fitting the thermocouple into one end of the tube 1 and welding it to the tube 1.

Further steps can be to provide a connection with the transmission conductors. An alternative can provide the radial enlargement ring 3 to be completely omitted and to be replaced by a radial annular shoulder formed by the axial compression of the tube 1.

It has to be noted how the object of the present invention can be applied also as a fastening means for an igniter.

Here, the fastening bushing can be mounted on the ceramic body of the igniter and retained in a smaller diameter area or by another manner.