WO2007019885A1

WO2007019885A1 - Bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly controlling gas flow in a burner

Info

Publication number: WO2007019885A1
Application number: PCT/EP2005/054065
Authority: WO
Inventors: Giorgio Offredi
Original assignee: Castfutura S.P.A.
Priority date: 2005-08-17
Filing date: 2005-08-17
Publication date: 2007-02-22

Abstract

Bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly controlling gas flow in a burner comprising a first central electrical contact member intended to engage a complementary first electrical contact terminal of the magnetic assembly and a second electrical contact terminal surrounding said first electrical contact terminal of the magnetic assembly in turn surrounding the first terminal, said first and second electrical contact member being mounted in a plug structure constituting an insulating member retaining said contact members and said first and second terminal being mounted on an electrical contact end of the magnetic assembly, while both first and second electrical contact member and both first and second terminal are positioned such that said first member and the corresponding terminal and the second member and the corresponding terminal are provided in such positions that engage one with the other contemporaneously and with a single mutual engagement movement, characterized in that at least one of the contact terminals and the corresponding contact member have mutual, movable coupling means, comprising cooperating elastic mutual interlocking surfaces that are partially oriented transversal to the direction of engagement/disengagement of connection member or members on contact terminal or terminals.

Description

Bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly controlling gas flow in a burner

The invention relates to a bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly controlling gas flow in a burner comprising a first central electrical con- tact member intended to engage a complementary first electrical contact terminal of the magnetic assembly and a second electrical contact member surrounding said first electrical contact member and intended to engage with a second electrical contact terminal of the mag- netic assembly surrounding also the first terminal, said first and second electrical contact member being mounted in a plug structure constituting an insulating member retaining said contact members and said first and said second terminal being mounted on an electrical connection end of the magnetic assembly, while both the first and the second electrical contact member and both the first and the second terminal are positioned such that said first member and the corresponding terminal and said second member and the corresponding terminal are provided in such positions that engage one with the other simultaneously and with one single mutual engagement movement .

Bipolar, coaxial connectors are known for a long time and are applied in varied technical fields. Generally this type of connectors comprise cylin- drically shaped male terminals that are brought into force engagement in corresponding tubular, cylindrical contact members contemporaneously generating both electrical contact between inner and external walls of ter- minals and of contact members and mechanical coupling by means of a certain action tightening tubular contact members on cylindrical terminals. To this aim generally the ductility of the electrically conductive material or materials composing terminals and especially tubular contact members is used. In some embodiments, tubular contact members are provided with an axial opening such to have an open transversal section and therefore to allow a radial opening out upon engagement on corresponding terminals. Such opening out is generally par- tially inelastic, this leads to a permanent and partially elastic expansion deformation. However the tubular shape with an axial opening in the tubular wall is adverse to an elastic recovery of the material that allows, upon uncoupling of contact members from corris- ponding terminals, a substantial recovery to initial size of the diameter of contact members prior to the first engagement action on the corresponding terminal.

In addition, the mutual contact between terminals and contact members has to be necessarily a large sur- face one in order to guarantee a sufficient mechanical constraint resistant up to a predetermined coupling force for resisting to accidental stress actions on contact members that therefore can lead to an accidental uncoupling. The mutual contact large surface and substantially the inelastic force coupling contact mem- bers with terminals leads to the drawback that after a long time surfaces in mutual contact can have a certain mutual attachment degree because of degradations due for example to oxidation or other effects wearing or changing materials, so the uncoupling may be at least very hard and arduous or even impossible to have without the risk of damaging the connector and/or the magnetic assembly or assembling supports thereof.

At present taps setting gas flow provided with a magnetic assembly are known and which magnetic assembly has at least ' a contact terminal having a disk-like enlarged head, the so called pin-like terminal. The other contact terminal is generally composed of the tap case or at least the housing case in the tap for the magnetic assembly. The contact with the second conductor of a thermocouple, generally with the so called cold junction, that is with the external sheath of the thermocouple occurs through the generally metallic mounting frame of the tap, the cable from the electrode of the thermocouple being secured thereto with the assistance of an eye terminal of the cable that is tightened to the mounting frame of the tap near the tap by means of a tightening screw.

Moreover generally the other cable from the other conductor of the thermocouple, the so called hot junction or phase is connected to the corresponding pin- like contact terminal of the magnetic assembly by means of a connector of the type called "faston" engaging the enlarged head of the contact terminal by force engaga- ment according to a radial direction. Generally the so called faston connectors comprise a plate with lateral, longitudinal edges that are bent such to form two lateral tightening tabs. Said edges are rectilinear, so the contact with a disk-like enlarged head is generally tangential to said enlarged head and so electrical contact surfaces are very restricted.

It is to be noted in this case how known and above disclosed modes for connecting the thermocouple provide connection operations quite complicated and how the manufacturing of an enlarged head contact terminal prevents the use of axial or coaxial bipolar connectors with known structures and widely used in the specific field.

Regarding such axial connectors, anyaway all type of bipolar or even monopolar axial connectors, have the drawback of forming an axial extension of contact terminals of the tap magnetic assembly that have quite large overall dimensions with reference to spatial volumes at disposal for example in cooking plates, wherein generally the axis of contact terminals is generally oriented either towards the bottom side or towards the upper side of a case housing taps and burners, as well as ducts supplying gas and which case and which members compose the cooking plate. This has to be necessarily thin and at present the miniaturization inclination is to reduce to a greater extent overall dimensions above all as regards thickness.

Therefore the invention aims to manufacture a bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly controlling gas flow in a burner of the type described hereinbefore, such to overcome drawbacks of known connectors.

Particularly the invention aims also to provide a monopolar or bipolar connector even in the case of a contact terminal of the tap magnetic assembly having an enlarged head, that is the so called pin-like type.

The invention aims also at manufacturing a monopolar or preferably bipolar connector having very small axial overall dimensions.

The invention achieves the above aims by means of a bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly controlling gas flow in a burner of the type disclosed hereinbefore, wherein at least one of the two contact terminal of the tap magnetic assembly has disk- like contact enlarged head and the relevant contact member connected to the cable for the connection to the thermocouple has a cup-like shape having a plurality of perimetric flaps that elastically oscillate radially outwards, which flaps are aligned along a perimeter that substantially corresponds to the perimeter of the enlarged head of the contact terminal, dimensions of such perimeter being such that flaps elastically oscil- late outwards upon an axial coupling of the cup contact member on the enlarged head contact terminal by generating at least electrical contact surfaces along the edge of the enlarged head.

The bottom wall of the cup contact member may be provided also in such a position to generate a contact with the enlarged head or to remain spaced therefrom.

Advantageously, contact flaps of the cup contact member have such a shape to have at an intermediate axial position a groove housing the perimetric edge of the contact enlarged head of the enlarged head contact terminal .

According to a further characteristic, the magnetic assembly of the tap has a further contact terminal surrounding the enlarged head contact terminal and having also a coupling end composed of a radially projecting annular edge, the corresponding contact member being composed of a cup member having an annular bottom wall with an opening for the passage of the cup contact member associated to the enlarged head central contact terminal.

In order to reduce axial overall dimensions of the connector, the two cup contact members, the central one and the annular external one surrounding said central contact member have an axial extension that substan- tially corresponds to or is slightly greater than travel coupling the corresponding contact terminals, while from bottom walls thereof radial extensions connecting and securing to the corresponding cable connecting the associated electrode of a thermocouple branch off, bottom walls of the two cup contact members being provided at a certain axial distance one with respect to the other and being coplanar to radial extensions connecting and securing the corresponding connection cable. Still according to an advantageous characteristic between the two contact members an insulating member is provided comprising two concentric housings for the more external cup contact member with annular bottom and for the central cup contact member respectively and walls delimiting said housings inserted among faced sides of the two contact members.

Even the insulating member comprises a radial extension coinciding with radial extensions connecting and securing the cable connecting the corresponding electrode of the thermocouple, which radial extension of the insulating member is interposed between said two coinciding radial extensions connecting and securing the two contact members.

Still according to a further improvement, the in- vention provides that said radial connection extension provides an engaging housing that is open on the corresponding axial side for each of the two radial extensions of contact members respectively.

Because of this arrangement, a bipolar connector has been advantageously provided with axial coupling direction for enlarged head contact terminals.

Particularly the pipe shape drastically limits axial overall dimensions of the connector, leading to a reduction of said overall dimensions for a distance comprised between two and three cm than usual axial connectors .

It is to be noted how the pipe shape can be applied also to conventional axial connectors.

According to a further characteristic of the in- vention it provides separately or in combination a bi- polar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly- controlling gas flow in a burner of the type disclosed hereinbefore wherein at least one of the two contact terminals and the corresponding contact member have electrical connection means composed of contact flaps with a restricted angular extension on the contact member and of an annular cylindrical contact surface on the contact terminal or vice versa and which contact members and corresponding contact terminals comprise cooperating surfaces for the mechanical, elastic and mutual coupling that are at least in part oriented transversally to the direction of engagement/disengagement of connection member or members in or on contact terminals.

According to an advantageous characteristic, the connector is characterized in that contact surfaces of at least a connector member and of the corresponding contact terminal are at least partially composed even of electrical contact surfaces transverse to a direction of mechanical coupling to the contact member on the contact terminal provided also with at least a contact surface transverse to the direction of mechanical engagement . Moreover electrical contact surfaces of at least one of the contact members are composed of at least one, preferably two, three or more thin contact protrusions arranged on a close surface having longitudinal axis oriented in the direction of coupling between the contact member and the corresponding terminal, which axial protrusions have a thin angular extension and have a shape like a sector complementary to a closed electrical contact surface and with axis parallel to the direction of coupling provided on the contact ter- minal .

Electrical contact axial protrusions adhere with a certain pressure on coincident inner surfaces of the closed contact electrical surface on the terminal.

Electrical contact protrusions of the contact mem- ber have also bosses, preferably rounded on the side that is in contact against the closed electrical contact surface of the contact terminal, which bosses have a such a radial projection that at least at an outermost point are tangent to an ideal closed surface of radial extension envelope slightly greater than the closed electrical contact surface of the contact terminal, upon engagement in said closed contact surface of the contact terminal exerting a radial compression force against said surface for generating a more heavy electrical contact.

According to a first advantageous embodiment at least the contact member and/or the corresponding contact terminal are provided with said elastic means for movable interlocking. A first embodiment provides that a first contact terminal associated to the magnetic assembly of the . tap controlling gas flow comprises an enlarged head-like end, while the corresponding contact member is made with a cup shape the lateral wall being partially open and composed of at least two perimetric axial tabs ex- tending for a partial angular sector of the total perimeter of the cup member.

A preferred embodiment provides that said contact member cooperating with said central contact terminal has a cup shape with a perimetric wall composed of a rim of perimetric flaps separated one with respect to the other by axial notches or slots and whose number can varied between two, three, four or more of said axial flaps. Advantageously said flaps are shaped and at least along their inner surface have at least one, preferably two annular radial, rounded recesses arranged one near the other referring to the axial extension of the cup member and forming therebetween a groove engaging the peripheral edge of the enlarged head of the contact terminal .

According to a further characteristic, at the open end of the cup contact member said recess forms a rounded lead-in surface upon which the also rounded pe- rimetric edge of the enlarged head of the contact terminal acts.

Prefarably both cup contact member and corresponding central terminal have a rotational symmetry, particularly are symmetric by rotation with respect to the central axis oriented in the coupling or engagement direction.

Due to this characteristic, when the cup contact member is axially pushed against the central terminal, the enlarged head thereof cooperates with the lead-in surface of said cup contact member formed by the first annular recess thereof and it leads to radial widening or bent of flaps that elastically snap rearwards when the enlarged head is inserted in the cup contact member in such an axial extent that it goes beyond the minimum inner diameter point of said recess, while the cup contact member is mechanically locked on the enlarged head when it reaches the intermediate region between the two annular radial recesses.

Therefore the two annular recesses form therebe- tween an enlarged annular groove snapping the enlarged head, said region having a diameter slightly smaller than the diameter of the enlarged head of the contact terminal and such that flaps are radially compressed by a predetermined elastic force against the perimetric edge of the enlarged head of the contact terminal, while said intermediate region axially has a length that is at least equal to or slightly greater than the axial thickness of said enlarged head of the contact terminal . Said annular groove snapping the enlarged head of the central contact terminal or at least the inner surface contacting the edge of said enlarged head and said enlarged head or at least the edge of said enlarged head form surfaces for the electrical connection be- tween central contact terminal and corresponding cup contact member, while the mechanical coupling is due to lateral walls of the snap groove that are composed of two faced faces of two subsequent annular recesses.

A possible locking mechanical component is com- posed of the tightening force exerted by the bottom wall of the snap groove on the perimetric edge of the enlarged head of the central contact terminal.

According to a further characteristic of the invention, at least one of the two contact members has an electrical contact surface that is oriented transverse to, particularly perpendicular to the coupling direction, while the corresponding contact terminal associated to the magnet has a corresponding electrical contact surface parallel to the electrical contact surface of the contact member the mechanical coupling between said two parts being formed at least by a pair of perimetric flaps diametrically opposite provided on the contact member and axially projecting in the direction engaging or coupling the contact member on the corre- sponding contact terminal and which flaps have radially inner teeth and cooperating by release snap in external recesses provided on the contact terminal, preferably an external perimetric annular groove.

Teeth on flaps associated to the contact member and the groove on the corresponding contact terminal are provided at such an axial distance from the corresponding electrical contact surface that upon condition adhering electrical contact surfaces one with the other, teeth of flaps of the contact terminal engage by release in notches or annular groove of the contact terminal .

According to a further characteristic, the contact member is composed of a flat ring having contact protrusions arranged along the inner perimeter of said contact ring and having a restricted angular extension, that is like a ring sector, and are intended to adhere to the inner surface of the ring of a coaxial contact bushing of the contact terminal which bushing at the free front-end side has an annular front-end surface substantially fitting with the ring forming the contact member, while said ring along the radially outermost perimeter has two, three or more axial tabs carrying or shaped such to form at a certain axial distance from the ring surface an inner radial tooth that can be elastically moved radially outwards and while said snap groove or said snap notches are made in the external sheath surface of the bushing at a predetermined axial distance from the free annular front-end surface contacting the ring of the contact member. According to a further characteristic, the ring forming the contact member and the bushing forming the contact terminal associated thereto are coaxial to the cup contact member and to the complementary enlarged head of the central contact terminal . Referring to a further characteristic, the cup contact member and/or the ring contact member have radial connection extensions for the mechanical and electrical connection of a conductor.

In the specific application, the hot junction of the thermocouple is connected by means of an electrical cable to the cup contact member and by this latter it can be connected to the central contact terminal of the magnetic assembly, while the annular contact member is connected to the cold junction of the thermocouple and by this latter it is connected to the contact terminal composed of the bushing and connected to the ground.

An advantageous embodiment provides for the two contact members to be mounted in an pipe-like insulating member having an axial annular recess on the en- gagement side that is complementary to and intended to house the annular contact member and a central axial hole composing the housing for the central cup contact member.

The pipe insulating member has a cylindrical wall separating the cup contact member from the annular contact member forming the lateral inner wall delimiting the annular recess housing the annular contact member and the external lateral wall delimiting the through hole housing the central cup contact member. The central contact terminal and the coaxial bushing-like contact terminal are spaced such to form a annular hollow with a radial length and a radial depth corresponding to the radial length of walls of cup contact member and of cylindrical wall separating the lat- ter from the annular contact member, so that in the assembled condition of the connector said inner cilindri- cal wall of the insulating member overlaps the inner wall of the bushing- like contact terminal.

The pipe insulating member has a radial extension in whose two opposite sides referring to the axis of contact members and/or to the engagement direction there are provided recesses, for radial extensions connecting conductors of the thermocouple, housing the cup contact member and the annular contact member respec- tively. In addition according to a further advantageous characteristic, the cup contact member and the annular contact member have locking means by release snap in the insulating member. Said means are composed of one, two or more elastic snap flaps and/or tabs cooperating with complementary recesses in the insulating member.

Advantageously release snap flaps or tabs are oriented in the coupling or engaging direction and elasti- cally enter inwards in the radial direction, while snap recesses are radial recesses with engagement surfaces transverse to the direction for engaging and/or coupling contact members and contact terminals one with the other. Particularly release snap tabs or flaps are oriented in a direction that conically diverges in the direction of their free end said free end being provided on the side opposite to the side for the introduction of the corresponding contact member in the insulating member and can radially oscillate inwards, so that upon the introduction of the contact member in the insulating member, said snap flaps or tabs are first radially pushed inwards and radially snap outwards in engagement recesses when the contact member is in the final assem- bling position in the insulating member.

Advantageously the coupling direction corresponds to the direction engaging the contact members on contact terminals.

According to a preferred embodiment, at least one of the contact members have more than two flaps or tabs for the snap inside the insulating member arranged along a circumference coaxial to the central axis of the cup and/or ring contact member.

Referring still to a further characteristic, the insulating member has radial bosses for stopping the introduction of the cup contact member which radial bosses are axially aligned with axial slots separating tabs forming the lateral sheath wall of the cup contact member and cooperating with the bottom wall of said slots.

Moreover, the insulating member can also have stop abutments against the enlarged head of the contact terminal abutting against the front-end surface of the enlarged head of the contact terminal . Such abutments can be composed of radial bosses stopping the introduction of the cup contact member in the insulating member.

In a particular embodiment, along the sheath surface formed by axial contact tabs the cup contact mem- ber has snap axial flaps or tabs of the type radially elastically flexible inwards and are provided as a rim of said snap flaps or tabs and are axially aligned with a rim of corresponding snap radial recesses provided in the wall separating the insulating member surrounding the cup contact member and a rim of axial slots separating contact perimetric tabs of the cup member that are provided in an intermediate angular position between two adjacent snap tabs or flaps, and in a position coinciding with corresponding inner radial bosses stopping the introduction of the cup contact member in the insulating member.

Particularly snap tabs or flaps are formed by notches along two axial or substantially axial sides and along a side joining said two axial or substan- tially axial sides in the material wall forming contact tabs of the cup contact member.

In the assembled condition of the connector the two contact members are locked to the insulating member in a position engaged in said insulating member by said snap flaps or tabs.

It has to be noted how the assembling of contact members on contact terminals can be carried out in sequence and in a separate manner for the two contact members and the insulating member, in a first step by applying the annular contact member on the cylindrical contact terminal and then by inserting above the annular contact member the insulating member till it is brought in stop abutment against the annular contact member while as the last step the cup member is engaged on the enlarged head central terminal through the central hole of the insulating member of the annular contact member, till said cup contact member is in a stop engagement position on said terminal and simultaneously in a locking position in the insulating member. To this aim, the position of snap flaps or tabs with respect to the position of contact members in the condition engaged on the corresponding contact terminal and of complementary recesses engaging snap flaps or tabs on the insulating member with respect to the as- sembling position thereof on contact terminals and with respect to flaps or tabs snapping on contact members, preferably the relevant position of said snap flaps or tabs and engaging recesses with reference to the engagement direction is such that upon coupling condition of contact members on corresponding contact terminals, the two contact members are perfectly engaged in the insulating member in the locking condition inside said insulating member.

With reference to the separation of contact mem- bers from contact terminals, that occurs in such a way that three parts that is contact members and the insulating member remain joined together forming a kind of bipolar pipe plug.

A subsequent coupling of contact members on corre- sponding terminals may occur at the same time in the assembled condition of the two contact members on the insulating member as bipolar plug.

Due to above structural features, the invention allows to overcome limits of coaxial bipolar connectors wherein electrical and mechanical connection occur on cylindrical surfaces by radial force of substantially cylindrical members.

It is easy to note how the shape of contact members give them a greater elasticity and then a pre- servetion of elastic features for more time. The mechanical coupling force is exerted more by the component due to elastic deformation than by the one due to inelastic deformation and the recovery to initial conditions upon uncoupling is almost a complete one or however is greater than known connector. The assembling in sequence of members guarantees a visual control of conditions for a correct electrical and mechanical connection. Moreover surfaces among which electrical connection occurs are separated from connector parts intended to generate the mechanical connection.

Furhter characteristics and advantages of the invention will be more evident from the following description of a non limitative embodiment shown in attched drawings, wherein:

Figures 1 to 3 are three exploded and perspective views of the connector according to the invention taken from three different angles.

Figures 4 and 5 are two perspective views taken from different angles of the insulating member.

Fig.6 is a perspective view of the connector composed of contact members associated to cables connecting the thermocouple and contact terminals associated to a magnet of a tap setting supplying gas flow to burner in the coupling condition, the magnet and the tap being omitted and only a part of the tap body carrying terminals being shown.

Fig.7 is a top and perspective view on the connector according to the invention. Fig.8 is a perspective view of a bottom detail of the connector according to fig.7.

Fig.9 shows two contact members associated to cables of the thermocouple and insulating member in the assembled condition one with respect to the other and according to a section axial plane parallel to the ra- dial extension of contact memebrs and of insulating member .

Fig.10 is a section of the part according to fig.9 but according to a plane substantially perpendicular to the section plane according to figure 9.

Fig.11 is a bottom view of an half of the connector part shown in previous figures 9 and 10.

Fig.12 is a view similar to the one of fig.10 but according to a different perspective angle. Fig.13 is an perspective exploded view of a variant embodiment .

Fig.14 is a section perspective view of the variant embodiment of fig.13.

Figures 15 to 17 illustrate a further variant of the connector according to the present invention and to the preceding drawings.

With reference to figures these show various views of a bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic as- sembly controlling gas flow in a burner.

The controlling magnetic assembly, typically an electromagnet, is housed inside the body of a tap supplying gas that sets said tap. Such taps are known and a tap of this type is disclosed for example in European Patent EP 619 460.

In figures only two contact terminals 1 and 2 are shown being part of the housing of the magnetic assembly. The contact terminal 1 is composed of a central cylindrical member with an enlarged head 101 that is electrically insulated from a cylindrical housing mouthpiece 3. This housing mouthpiece 3 is part of the housing of the magnetic assembly and it is ground connected. On said mouthpiece 3 there can be mounted the terminal 2 composed of a bushing that can be engaged on said mouthpiece 3 for example by means of threads.

The enlarged head 101 has a disk-like shape perpendicular to the axis of the terminal and it can be made by means of an annular groove provided at the end portion of the central contact terminal 1. In this case the enlarged head 101 has the same diameter or substantially the same diameter of the central contact terminal 1. Alternatively the enlarged head 1 can be otherwise made and it can have always a diameter greater than the remaining part of the central contact terminal 1. The housing mouthpiece 3 that is electrically insulated from the central terminal 1 has a diameter greater than the central terminal 1 and than the enlarged head, while the threaded bushing composing the terminal 2 and secured to the end of the housing mouth- piece 3 has a central through hole 102 with a diameter greater than the enlarged head 101. At the edge of the hole 102 opposite to the mouthpiece 3 there is provided a radial enlargement 202 forming an external annular groove 302. Generally thermocouples have two electrodes that are in contact one with the other at a thermosensitive end. Variations of temperature generate various potential differences between the two electrodes. From the latters an electrical connection cable branches off which has to be connected to one of the two contact terminals 1, 2 respectively of the magnetic assembly. The electrical connection of the two cables occurs by means of two contact members 3, 4 that can be engaged and locked in a mechanically movable way and at the same time generating the electrical connection on the corresponding coupling terminal 1, 2.

Generally the central contact terminal 1 is connected to the thermocouple electrode that is called hot junction of the thermocouple, that is to the central electrode mounted inside a cylindrical electrode so called cold junction and that is connected to the external cylindrical terminal 2 that in turn is connected to the ground.

Cables are secured to two contact members 3, 4 by welding or by means of a mechanical tightening among tightening tongues. Thus both the mechanical coupling of the cable to the contact member 3 and 4 and the electrical connection between cable and the corresponding contact member 3, 4 occur. The contact member associated to the external cylindrical contact terminal 2 of the magnetic assembly is composed of an annular flat member made of electrically conducting material having a diameter and a radial length that substantially correspond to the diame- ter and to the radial length of the front-end edge of the terminal 2 surrounding the hole 102. Surfaces for the electrical contact between said terminal and said annular contact member are mainly composed of axial protrusions 803 arranged along the inner perimeter and having a reduced axial extension and a restricted ex- tension in the circumferential direction. These have an external diameter that substantially correspond to the inner diameter of the hole of the bushing 2 and however such to exert a close electrical contact radial com- pression with said contact bushing 2. Moreover in the assembled condition of the annular contact member 3 on said bushing, the ring portion comes to adhere to the corresponding annular front-end side of the bushing 2 forming also annular mutual contact surfaces indicated by 103 and 402. The mechanical locking of the annular contact member 3 in condition contacting the cylindrical contact terminal 2 is made by means of at least two diametrically opposite flaps 203 extending from the peripheric edge of the annular contact member 3 in the axial direction and towards contact terminal 2 and having a S-like shape with an appearance converging towards the centre of the annular contact member 3 in order to form snap teeth cooperating with annular peripheric groove 302 of the contact terminal 2. In this case the axial length of flaps 203 is such that by means of ends rounded towards said groove 302, which ends form snap teeth 303, in a condition of engagement of the snapping teeth 203 in the groove 302, the electrical contact surfaces 103 and 402 are firmly retained in contact one with respect to the other generating the necessary electrical contact. Flaps are shaped' in such a way to generate a radial force for the engagement in the groove 302 and are elastically pliable in the external radial oscillation direction, while elastically snapping inside the groove 302. The S shape is asymmet- rical and it allows to cooperate with lateral walls of the groove 302 that are suitable correspondingly rounded, in order to generate even a force component in the axial compression direction of the annular contact member 3, that is of the electrical contact surface of said member 3 against the front-end annular edge 402 of the contact terminal 2. The cable of the thermocouple electrode corresponding to the cold junction is secured as disclosed above to the end of a radial extension 403 ending with a member tightening the cable and for electrically connecting it to the contact member composed of a U member 503 that forms two flaps that can be bent against the cable so that said cable is thightened between the bottom of the U section and said flaps bent against the cable.

From the side of the annular member 3 opposite to the one of flaps two snap flaps 603 branch off in an intermediate position with reference to the radial width of the annular member 3 on each one of which snap flaps 603 there is provided a tab that can elastically oscillate between a position radially bent outwards in a position less radially bent or substantially aligned at level with the corresponding snap flap 603. Advantageously snap flaps are made by notching a central re- gion of flaps 603 along three edges and substantially along two opposite axial or substantially axial edges and along a transversal connection edge, that is preferably provided on flap side faced towards the annular connection member 3. At rest condition or firm posi- tioning flaps are oscillated in a position that ra- dially diverge outwards and in which position they firmly recover after being subjected for example to a radial push inwards .

An insulating member 5 has an annular axial hous- ing 105 delimited on the radially inner side by a cylindrical wall 205 and at the outside by the peripheri- cal cylindrical wall 205 of the insulating member 5. The annular axial groove-like bottom of said annular housing is the abutment surface of the annular contact member, while in said bottom wall two slots 305 are provided axially coinciding with snap flaps 603 of the annular contact member 3 and having such a size that said flaps engage by elastic deformation of tongues 703 in said slots 305. The radially external lateral wall of each slot has an hollow 405 forming an axial abutment step 505 against which the transversal edge of the corresponding tongue 703 cooperates. The axial position of said transversal edge of tongues 703 and of the cooperating step 505 is such that in condition of mutual engagement, the annular contact member is perfectly housed in the housing axial groove and in a position adhering to the bottom thereof.

According to a further characteristic, the annular contact member 3 has flaps like a sector of a circle even at the inner perimeter. Said flaps 803 are coaxial to said annular member and are electrical contact flaps arranged in contact with the inner cylindrical wall 105. Inner flaps 803 are radially aligned with external elastic flaps 203 so to improve the mechanical coupling action engaging the inner surface of the cylindrical contact terminal 2 by inner overlapping, while flaps 203 engage said terminal 2 by the external perimeter side. Some inner axial flaps 803 are arranged even not radially coinciding with external flaps 203. Moreover some flaps 803 and/or 203 may be housed in radial recesses or between axial walls for an antirotation retaining of annular contact member 3.

Also the insulating member 5 has a radial extension 605 and in turn it has a central depression 705 wherein the radial extension 403 of the annular contact member 3 is housed in an engaged position. Moreover the radial extension has an external gripping knurling on the two opposite lateral walls oriented in the axial direction. The axial extension of the external cylindrical wall 205 substantially corresponds to the one of flaps 203 of the annular contact member 3 or it is slightly greater than or such to cover the groove 302 on the contact terminal 2 in the assembled condition of con- nector (fig .6) . In this condition a not round radial extension 502 for grasping by rotation the contact terminal 2 prevents the admission to the groove 302 being positioned substantially at level to the annular lateral wall of the groove 302 opposite to the end con- tacting the annular contact member 3. Moreover on the side of the radial extension 605 the external cylindrical wall 205 is open for the passage of the radial extension 403 of the annular contact member 3. The inner diameter of the external cylindrical wall 205 is slightly greater than the one of mechanical locking ax- ial tabs 203 so to allow the straddle thereof upon going beyond the annular enlargement surrounding the edge of the opening 102 of the contact terminal 2 and forming the lateral wall on the electrical contact front- end surface 402 when the annular contact member 3 is coupled to the cylindrical contact terminal 2.

The inner cylindrical wall 105 of the insulating member 5 is axially longer than the external one and at least for a partial axial length it interposes the enlarged head 101 of the contact terminal 1 separating and insulating it from the inner surface of the contact terminal 2. Such cylindrical wall 105 delimits a central through hole 805 wherein a cup contact member 4 engaging on the central contact terminal 1 is intended to be inserted, mechanically engaging the enlarged head 101 of said terminal 1 and generating the electrical contact. On the side of the insulating member opposite to the side housing the annular contact member 3 the radial extension 605 of the insulating member 5 has a central recess housing a radial extension 104 of the cup contact member 4 to which the cable of the other electrode of the thermocouple is intended to be secured in a way substantially similar to that described for the annular contact member 3. In the assembled condi- tion of the cup contact member 4 in the insulating member 5 the radial extension 104 of the cup contact member 4 is housed by disappearance in said central recess 905, while the wall delimiting the through opening 805 is experimentally open at the recess 905. The cup contact member 4 has a sheath wall formed of a plurality of axial tabs 204 having the same axial extension and such an angular extension that axial contact tabs 204 are separated one with respect to the other by axial notches 304 substantially for their to- tal axial length. The end part of axial tabs 204 towards the free end has the sector corresponding to two rounded radial annular recesses 404, 504 that are axi- ally aligned one near the other and forming therebetween an inner radial groove 604. Advantageously rounded radial recesses 404, 504 and the radial intermediate groove 604 are made by a deformation of tabs so the external wall thereof has substantially the same shape of the inner wall.

The inner smallest diameter of the two rounded ra- dial recesses in the axial direction is smaller than the diameter of the circular enlarged head 101 of the contact terminal 1, while the inner diameter of the annular groove 604 interposed between said two radial recesses 404, 504 is slightly smaller or substantially equal to the diameter of the enlarged head 101 of the central contact terminal 1. The wall of the annular recess 404 on the free end of the cup contact member 4 forms a conical lead-in surface that upon the axial coupling on the enlarged head 101 of the central con- tact terminal 1 coopoerates with the peripheral edge thereof in order to determine the elastic radial straddling of tabs that is necessary to pass beyond the corresponding radial recess 404, while the enlarged head 101 progressively axially penetrates inside the cup contact member 4. When going beyond said first radial annular recess 404, the peripheral edge of the enlarged head remains engaged in the radial groove 604 that radially fastens it. Tabs 204 hence remain slightly outward radially straddled generating a radial tightening force of the bottom wall of the radial groove 604 against the perimetral edge of the enlarged head because of their elastic force for the recovery in the rest position.

Advantageously the thickness of the enlarged head 101, at least along the perimetric edge and the shape thereof substantially correspond to the thickness and the shape of the bottom wall of the inner radial annular groove 604 intended to engage the enlarged head 101. In this condition the electrical contact is given by surfaces of inner radial groove 604 and by perimetric edge of the enlarged head, while the mechanical retention is at least further assisted by lateral radially hollow walls of the two inner radial recesses 404, 504 between which the groove 604 is interposed. The inner diameter of the inner cylindrical wall 105 of the insulating member 5 is slightly greater than the diameter of the sheath wall of the cup contact member 4 to an extent sufficient to guarantee the radial outward straddling of contact tabs 204 for the coupling with the enlarged head 101 of the corresponding contact terminal 1.

The end region of the cup contact member 4 opposite to the one coupling the enlarged head 101 of the corresponding central contact terminal 1 has a substan- tially cylindrical appearance and an axial extension that corresponds to the one of a corresponding portion of the wall of hole 805 wherein a step annular recess 1005 is provided. From the inner sheath surface of the step annular recess 1005 in a position axially aligned with each one of axial slots 304 separating contact tabs 204 branch off an inner radial tooth 1105 for stopping the axial introduction of the cup contact member 4 inside the insulating member 5 respectively. Such radial stop teeth 1105 abut against bottom sides of slots 304 separating contact tabs 204 and are provided in axial position so when in condition stopping the introduction of the cup contact member 4 in insulating member, contact tabs 204 do not project beyond the inner cylindrical wall 105 completely overlapping thereto, while on the opposite end the bottom of the cup contact member is substantially at level or approximately at level with the corresponding side of the insulating member 5 and the radial extension 104 is engaged in the central recess 905. It is possible to provide for radial teeth 1105 stopping the introduction of the cup contact member 4 inside the insulating member 5 to have an axial length such to constitute at the same time a stop for the introduction of the cup contact member 4 on the enlarged head of the contact terminal 1 axial ends of said teeth being abutted against the faced side of the enlarged head 101 of the central contact terminal 1.

Analogously to what disclosed with reference to the annular contact member 3 , even the cup contact mem- ber 4 has means for snapping inside the insulating mem- ber retaining said cup contact member 4 inside the insulating member.

Analogously to the annular contact member 4, the cup contact member 4 has at least a pair of snap flaps 704, preferably a rim of snap flaps 704 that are made of U notches in the wall of the end part of the sheath wall of the cup contact member 4 opposite to the free end of contact tabs 204.

Flaps or tabs diverge towards said end opposite to the coupling one, that is the free one of contact tabs 204 and can elastically oscillate inwards, while automatically passing in the rest condition diverging outwards .

Said snap flaps 704 are intended to cooperate by their free edge transversal to the axis with faced retaining walls 1305 composed of corresponding sides transversal to the axis of notches 1205 obtained in inner walls of the cylindrical annular recess 1005 of the wall of the through hole 805. In the assembled condi- tion of the cup contact member inside the insulating member 5, the cup contact member is axially retained against a displacement in two axial directions by means of introduction stop teeth 1105 cooperating with bottom sides of slots 304 separating contact tabs 204 and by radial snap tabs 704 cooperating with snap recesses 1205.

Snap tabs 704 are inserted angularly to axial slots 304.

In first assembling condition it is possible to mount the annular contact member 3 on the corresponding cylindrical terminal 2 one after the other. Subsequently the insulating member 5 and finally the cup contact member 4. It is also possible to couple the insulating member 5 with the cup contact member and to mount said two members together on terminals to which the annular contact member 3 has already been coupled.

After the first assembling, three members 3, 4 and 5 that is two contact members 3 and 4 and the insulating member 5 carrying or housing them remain con- strained one with the other. Therefore it is possible to withdrawn said three members from contact terminals without being separated one from the other, but in a single piece as a connector similar to a pipe connector. Subsequent coupling to contact terminals of a magnetic assembly may occur in the assembled form of three members 3, 4 and 5 without the requirement of a separation one with respect to the other.

Obviously the invention is not to be considered limitative to disclosed and shown embodiments, but it may comprise all variants referring to the same guiding principle described above and claimed below. So for example the shape may not be the rotation symmetric one and particularly the symmetry has not to be necessarily the circular one.

Referring to snap flaps 704 and corresponding engagement recesses 1205, 1305 these can be also made by providing snap flaps integral with the insulating member 5 and recesses as slots on the cup contact member 4 instead of flaps 704. Moreover figures 13 and 14 show a variant embodiment, wherein in order to increase the electrical contact between axial protrusions of the annular contact member 3 with the inner surface of the cylindrical con- tact terminal 2, each protrusion 803 on the face faced towards said inner surface of the cylindrical contact terminal 2 carries a buckle-like boss or with a lenticular shape indicated by 903. Bosses have such a thickness that result tangent to an external circumfer- ence with a diameter slightly greater than the diameter of the cylindrical surface of the cylindrical contact terminal 2. The lenticular shape or however flaring and/or beveled and/or with a progressive appearance is an engaging lead-in in the cylindrical contact terminal 2. Due to this characteristic, protrusions 803 are radially oscillated inwards generating an elastic force compressing them against the inner surface of the cylindrical contact terminal 2 improving the electrical contact between said terminal 3 and protrusions 803. In figures 15 to 17 a further variant of the connector according to the present invention is illustrated. In this figure the same reference numbers are used as in the previous figures for parts having in- detical structure or function. Additional parts are in- dicated by new reference numbers.

As a first feature, in the present variant the annular contact member 3 does not show the snap flaps 603 with the tabs 703 engaging the axial slots 305 of the insulating member 5. This insulating member lacks so the corresponding axial slots 305. The annular contact member 3 is held in position against the annular head end of the bushings forming the ciontact terminal 2 by means od the snapping action of the contact member 4 when it is engaged by snap connection to the enlarged head 101 of the contact terminal 1. In this condition the annular contact member 3 is pressed between the annular end surface of the contact terminal 2 and an internal annular surface of the insulating member 5, which surface can be continuous or discontinuous and is coaxial with the annular head end of the contact terminal 2.

Furthermore the annular contact member 3 lacks the axial peripheral flaps 203 engaging the external groove 302 of the contact terminal 2 but bears only the axial flaps 803 at the internal perimeter of the annular contact surface, which flaps comes into contact with the internal cylindrical surface of the contatct terminal 2.

Alternatively or in combination with the abive feature, the insulating member 5 itself can be provided with means for a snapping engagement with the annular contact terminal 2. In this case the annular terminal 2 is provided with radial outer teeth which cooperates with radial internal teeth of the insulating member 5. According to¹ the illustrated embodiment, the outer teeth of the annular member are formed by the lateral wall of the annular groove 302, while the insulating member has a continuous annular projection along its inner cylindrical surface which cooperates with the said lateral wall of the contact terminal 3 as a snap engagement .

As a further feature, the axial tabs 204 of the cup contact member 4 are shaped in such a way that they have tapered ends 1204. Still another featire consist in a cable retaining tongue 1505 provided at the radially outer end of the through recess 905 which forms a guiding channel for the cable which end is secured mechanically and in electrical contact with the radial extension 104 of the cup contact member 4. This cable retaining tongue 1505 is made of the same plastic material as the insulating member 5 and has an intrinsic elasticity in order to be elastically bent for allowing passage of the cable either for engagement or for disengagement of the said cable. Advantageously the tongue departs in a cantile- vered way from a lateral wall of the recess or channel 905 and its free end terminates near the opposite lateral surface at a certain distance which is less than the typical cable diameter. Accordinbg to a further feature, the said tongue 1505 is also oriented in an inclined direction departing from the upper end of the lateral wall of the channel or of the recess 905 and is directed to the bottom side of the opposite lateral wall . As it can be appreciated by means of the preceding description of the different variants of the connector according to the present invention, this connector can also be employed in the case that no earth connection is needed by means of a cable. In some cooking devices, the earth connection is formed by the frame or the structure of the cooking device itself so that no earth cable is needed. Electrical connection to earth is achieved through the metallic and electrically conductive means for securing the thermocouple and the mag- netic assembly for controlling the gas flow in the burner. In this case the annular contact member 3 is not present and only the cup contact member 4 and the insulating memember 5 are provided. So the connector of the present invention, both provides with the same structure for effective functions of a bipolar connector and of a monopolar connector.

Claims

1. Bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly controlling gas flow in a burner comprising at least a first enlarged contact head electrical contact member, the so called pin-like one, intended to engage a complementary first electrical contact terminal of the magnetic assembly, characterized in that the rele- vant contact member connected to the cable for the connection to the thermocouple has a cup shape having a plurality of perimetric flaps that elastiσally oscillate radially outwards, which flaps are aligned along a perimeter that substantially corresponds to the perime- ter of the enlarged head of the contact terminal, dimensions of such perimeter being such that flaps elas- tically oscillate outwards upon an axial coupling of the cup contact member on the enlarged head contact terminal by generating at least electrical contact sur- faces along the edge of the enlarged head.

2. Bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly controlling gas flow in a burner comprising a first central electrical contact member intended to en- gage a complementary first electrical contact terminal of the magnetic assembly and a second electrical contact member surrounding said first electrical contact member and intended to engage a second electrical contact terminal of the magnetic group surrounding also the first terminal, said first and second electrical contact member being mounted in a plug structure constituting an insulating member retaining said contact members and said first and said second terminal being mounted on an electrical contact end of the magnetic assembly, while both first and second electrical contact member and both first and second terminal are positioned such that said first member and the corresponding terminal and said second member and the corresponding terminal are provided in such positions that engage one with the other contemporaneously and with a single mutual engagement movement, characterized in that at least one of the two contact terminals of the magnetic assembly of the tap has a contact enlarged head of the disk-like type or an annular edge radially projecting and the relevant contact member connected to the cable for the connection to the thermocouple has a cup shape having a plurality of perimetric flaps that elastically oscillate radially outwards, which flaps are aligned along a perimeter that substantially corre- sponds to the perimeter of the enlarged head of the contact terminal, dimensions of such perimeter being such that flaps elastically oscillate outwards upon an axial coupling of the cup contact member on the enlarged head contact terminal by generating at least electrical contact surfaces along the edge of the enlarged head.

3. Connector according to claims 1 or 2, characterized in that the bottom wall of the cup contact member may be provided also in such a position to generate a contact with the enlarged head or to remain spaced therefrom.

4. Connector according to one or more of the preceding claims, characterized in that contact flaps of the cup contact member have such a shape to have at an intermediate axial position a groove housing the perimetric edge of the contact enlarged head of the enlarged head contact terminal.

5. Connector according to one or more of the preceding claims, characterized in that the magnetic as- sembly of the tap has a further contact terminal surrounding the enlarged head contact terminal and having also a coupling end composed of a radially projecting annular edge, the corresponding contact member being composed of a cup member having an annular bottom wall with an opening for the passage of the cup contact member associated to the .enlarged head central contact terminal .

6. Connector according to one or more of the preceding claims, characterized in that in order to reduce axial overall dimensions of the connector, the two cup contact members, the central one and the annular external one surrounding said central contact member have an axial extension that substantially corresponds to or is slightly greater than travel coupling the corresponding contact terminals, while from bottom walls thereof radial extensions connecting and securing to the corresponding cable connecting the associated electrode of a thermocouple branch off, bottom walls of the two cup contact members being provided at a certain axial dis- tance one with respect to the other and being coplanar to radial extensions connecting and securing the corresponding connection cable.

7. Connector according to one or more of the preceding claims, characterized in that between the two contact members an insulating member is provided comprising two concentric housings for the more external cup contact member with annular bottom and for the central cup contact member respectively and walls delimiting said housings interposed among faced sides of the two contact members.

8. Connector according to one or more of the preceding claims, characterized in that even the insulating member comprises a radial extension coinciding with radial extensions connecting and securing the cable connecting the corresponding electrode of the thermocouple, which radial extension of the insulating member is interposed between said two coinciding radial extensions connecting and securing the two contact members.

9. Connector according to one or more of the pre- ceding claims, characterized in that said radial connection extension provides an engaging housing that is open on the corresponding axial side for each one of the two radial extensions of contact members respectively.

10. Connector according to one or more of the preceding claims, characterized in that between the two contact members there is provided an insulating member, at least one of the contact members and the insulating member being provided with cooperating release snap means.

11. Bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly controlling gas flow in a burner comprising a first central electrical contact member intended to en- gage a complementary first electrical contact terminal of the magnetic assembly and a second electrical contact member surrounding said first electrical contact member and intended to engage a second electrical contact terminal of the magnetic group surrounding also the first terminal, said first and second electrical contact member being mounted in a plug structure constituting an insulating member retaining said contact members and said first and said second terminal being mounted on an electrical contact end of the magnetic assembly, while both first and second electrical contact member and both first and second terminal are positioned such that said first member and the corresponding terminal and said second member and the corresponding terminal are provided in such positions that engage one with the other contemporaneously and with a single mutual engagement movement, characterized in that in the axial and engaging direction contact members have an extension that substantially corresponds to or is slightly greater than the axial coupling travel, while the remaining extension of said connectors is provided in the direction transverse to, particularly radial than the coupling direction that is an angled or pipe shape.

12. Bipolar electrical connector particularly for connecting flame detector thermocouples to a magnetic assembly controlling gas flow in a burner comprising a first central electrical contact member intended to engage a complementary first electrical contact terminal of the magnetic assembly and a second electrical con- tact member surrounding said first electrical contact member and intended to engage a second electrical contact terminal of the magnetic assembly surrounding also the first terminal, said first and second electrical contact member being mounted in a plug structure con- stituting an insulating member retaining said contact members and said first and said second terminal being mounted on an electrical contact end of the magnetic assembly, while both first and second electrical contact member and both first and second terminal are po- sitioned such that said first member and the corresponding terminal and said second member and the corresponding terminal are provided in such positions that engage one with the other contemporaneously and with a single mutual engagement movement, characterized in that at least one of the two contact terminals and the corresponding contact member have electrical connection means composed of at least a contact flap with a restricted angular extension on the contact member and of a cylindrical annular contact surface on the contact terminal or vice versa and which contact members and the corresponding contact terminals comprise cooperating elastic and mutual mechanical interlocking surfaces that are partially oriented transversal to the direction of engagement/disengagement of connection member or members on contact terminal or terminals.

13. Connector according to one or more of the preceding claims, characterized in that contact surfaces of at least a connector member and of the corresponding contact terminal are at least partially composed even of electrical contact surfaces transverse to a direction for the mechanical coupling of the contact member on the contact terminal provided also with at least a contact surface transverse to the direction of mechanical engagement.

14. Connector according to one or more of the preceding claims, characterized in that electrical contact surfaces of at least one of the contact members are composed of at least one, preferably two, three or more thin contact protrusions arranged on a closed surface having longitudinal axis oriented in the direction of coupling between the contact member and the corresponding terminal, which axial protrusions have a thin angular extension and have a shape like a sector complementary to a closed electrical contact surface and with axis parallel to the direction of coupling provided on the contact terminal .

15. Connector according to one or more of the preceding claims, characterized in that electrical contact axial protrusions adhere with a certain pressure on co- incident inner surfaces of the closed contact electrical surface on the terminal.

16. Connector according to one or more of the preceding claims, characterized in that electrical contact protrusions of the contact member have bosses, prefera- bly rounded on the side that is in contact against the closed electrical contact surface of the contact terminal, which bosses have such a radial projection that at least at an outermost point are tangent to an ideal closed surface of radial extension envelope slightly greater than the closed electrical contact surface of the contact terminal, upon engagement in said closed contact surface of the contact terminal exerting a radial compression force against said surface for generating a more heavy electrical contact.

17. Connector according to one or more of the preceding claims, characterized in that at least the contact member and/or the corresponding contact terminal are provided with said elastic means for movable interlocking.

18. Connector according to one or more of the preceding claims, characterized in that a second contact terminal associated to the magnetic assembly of the tap controlling gas flow comprises an enlarged head-like end, while the corresponding contact member is made with a cup shape the lateral wall being partially open and composed of at least two perimetric axial tabs extending for a partial angular sector of the total perimeter of the cup member.

19. Connector according to one or more of the pre- ceding claims, characterized in that said contact member cooperating with said central contact terminal has a cup shape with a perimetric wall composed of a rim of perimetric flaps separated one with respect to the other by axial notches or slots, and whose number can varied between two, three, four or more of said axial flaps .

20. Connector according to one or more of the preceding claims, characterized in that said flaps are shaped and at least along their inner surface have at least two annular radial, rounded recesses arranged one near the other referring to the axial extension of the cup member and forming therebetween a groove engaging the peripheral edge of the enlarged head of the contact terminal .

21. Connector according to one or more of the preceding claims, characterized in that at the open end of the cup contact member said recess forms a rounded lead-in surface upon which the also rounded perimetric edge of the enlarged head of the contact terminal acts.

22. Connector according to one or more of the preceding claims, characterized in that both cup contact member and corresponding central terminal have a rotational symmetry, particularly are symmetric by rotation with respect to the central axis oriented in the cou- pling or engagement direction.

23. Connector according to one or more of the preceding claims, characterized in that the two annular recesses form therebetween an enlarged annular groove snapping the enlarged head, said region having a diame- ter slightly smaller than the diameter of the enlarged head of the contact terminal and such that flaps are radially compressed by a predetermined elastic force against the perimetric edge of the enlarged head of the contact terminal, while said intermediate region axi- ally has a length that is at least equal to or slightly greater than the axial thickness of said enlarged head of the contact terminal.

24. Connector according to one or more of the preceding claims, characterized in that said annular groove snapping the enlarged head of the central contact terminal or at least the inner surface contacting the edge of said enlarged head and said enlarged head or at least the edge of said enlarged head form surfaces for the electrical connection between central contact terminal and corresponding cup contact member, while the mechanical coupling is due to lateral walls of the snap groove that are composed of two faced faces of two subsequent annular recesses.

25. Connector according to one or more of the pre- ceding claims, characterized in that a possible locking mechanical component is composed even of the tightening force exerted by the bottom wall of the snap groove on the perimetric edge of the enlarged head of the central contact terminal .

26. Connector according to one or more of the preceding claims, characterized in that at least one of the two contact members has an electrical contact surface that is oriented transverse to, particularly perpendicular to the coupling direction, while the corre- sponding contact terminal associated to the magnet has a corresponding electrical contact surface parallel to the electrical contact surface of the contact member the mechanical coupling between said two parts being made at least by a pair of perimetric flaps diametri- cally opposite provided on the contact member and axi- ally project in the direction engaging or coupling the contact member on the corresponding contact terminal and which flaps have radially inner teeth and cooperating by release snap in external recesses provided on the contact terminal, preferably an external perimetric annular groove.

27. Connector according to one or more of the preceding claims, characterized in that teeth on flaps associated to the contact member and the groove on the corresponding contact terminal are provided at such an axial distance from the corresponding electrical contact surface that upon condition adhering electrical contact surfaces one with the other, teeth of flaps of the contact member engage by release in notches or an- nular groove of the contact terminal .

28. Connector according to one or more of the preceding claims, characterized in that the contact member is composed of a flat ring having contact protrusions arranged along inner perimeter of said contact ring and having a restricted angular extension, that is like a ring sector, and are intended to adhere to the inner surface of the ring of a coaxial contact bushing of the contact terminal which bushing at the free front-end has an annular front-end surface substantially fitting with the ring forming the contact member, while said ring along the radially outermost perimeter has two, three or more axial tabs carrying or shaped such to form at a certain axial distance from the ring surface an inner radial tooth that can be elastically moved ra- dially outwards and while said snap groove or said snap notches are formed in the external sheath surface of the bushing at a predetermined axial distance from the free annular front-end surface contacting the ring of the contact member.

29. Connector according to one or more of the preceding claims, characterized in that the ring forming the contact member and the bushing forming the contact terminal associated thereto are coaxial to the cup contact member and to the complementary enlarged head of the central contact terminal.

30. Connector according to one or more of the preceding claims/ characterized in that the cup contact member and/or the ring contact member have radial connection extensions for the mechanical and electrical connection of a conductor.

31. Connector according to one or more of the preceding claims, characterized in that the hot junction of the thermocouple is connected by means of an electrical cable to the cup contact member and by this lat- ter it can be connected to the central contact terminal of the magnetic assembly, while the annular contact member is connected to the cold junction of the thermocouple and by this latter it is connected to the contact terminal composed of the bushing and connected to the ground.

32. Connector according to one or more of the preceding claims, characterized in that the two contact members are mounted in a pipe- like insulating member having an axial annular recess on the engagement side that is complementary to and intended to house the an- nular contact member and a central axial hole composing the housing for the central cup contact member.

33. Connector according to one or more of the preceding claims, characterized in that the pipe insulat- ing member has a cylindrical wall separating the cup contact member from the annular contact member forming the lateral inner wall delimiting the annular recess housing the annular contact member and the external lateral wall delimiting the through hole housing the central cup contact member.

34. Connector according to one or more of the preceding claims, characterized in that the central contact terminal and the coaxial bushing-like contact terminal are spaced such to form an annular hollow with a radial length and a radial depth corresponding to the radial length of walls of cup contact member and of cylindrical wall separating the latter from the annular contact member, so that in the assembled condition of the connector said inner cilindrical wall of the insu- lating member overlaps the inner wall of the bushing- like contact terminal.

35. Connector according to one or more of the preceding claims, characterized in that the pipe insulating member has a radial extension in whose two opposite sides referring to the axis of contact members and/or to the engagement direction there are provided recesses, for radial extensions connecting conductors of the thermocouple, housing the cup contact member and the annular contact member respectively.

36. Connector according to one or more of the pre- ceding claims, characterized in that the cup contact member and the annular contact member have locking means by release snap in the insulating member.

37. Connector according to claim 36, characterized in that said means are composed of one, two or more elastic snap flaps and/or tabs cooperating with complementary recesses in the insulating member.

38. Connector according to claim 36 or 37, characterized in that release snap flaps or tabs are oriented in the coupling or engaging direction and elastically enter inwards in the radial direction, while snap recesses are radial recesses with engagement surfaces transverse to the direction for engaging and/or coupling contact members and contact terminals one with the other.

39. Connector according to one or more of the preceding claims 36 to 38, characterized in that release snap tabs or flaps are oriented in a direction that conically diverges in the direction of their free end said free end being provided on the side opposite to the side for the introduction of the corresponding contact member in the insulating member and can radially oscillate inwards, so that upon the introduction of the contact member in the insulating member, said snap flaps or tabs are first radially pushed inwards and radially snap outwards in engagement recesses when the contact member is in the final assembling position in the insulating member.

40. Connector according to one or more of the pre- ceding claims, characterized in that the coupling di- rection corresponds to the direction engaging the contact members on contact terminals.

41. Connector according to one or more of the preceding claims, characterized in that at least one of the contact members have more than two flaps or tabs for the snap inside the insulating member arranged along a circumference coaxial to the central axis of the cup and/or ring contact member.

42. Connector according to one or more of the pre- ceding claims, characterized in that the insulating member has radial bosses for stopping the introduction of the cup contact member which radial bosses are axi- ally aligned with axial slots separating tabs forming the lateral sheath wall of the cup contact member and cooperating with the bottom wall of said slots.

43. Connector according to one or more of the preceding claims, characterized in that the insulating member can also have stop abutments against the enlarged head of the contact terminal abutting against the front-end surface of the enlarged head of the contact terminal.

44. Connector according to claim 39, characterized in that such abutments can be composed of radial bosses stopping the introduction of the cup contact member in the insulating member.

45. Connector according to one or more of the preceding claims, characterized in that the along the sheath surface formed by axial contact tabs the cup contact member has snap axial flaps or tabs of the type radially elastically flexible inwards and are provided as a rim of said snap flaps or tabs and are axially aligned with a rim of corresponding snap radial recesses provided in the wall separating the insulating member surrounding the cup contact member and a rim of axial slots separating contact perimetric tabs of the cup member that are provided in an intermediate angular position between two adjacent snap tabs or flaps, and in a position coinciding with corresponding inner radial bosses stopping the introduction of the cup con- tact member in the insulated member.

46. Connector according to claim 45, characterized in that snap tabs or flaps are formed by notches along two axial or substantially axial sides and along a side joining said two axial or substantially axial sides in the material wall forming contact tabs of the cup contact member.

47. Connector according to one or more of the preceding claims, characterized in that in the assembled condition of the connector the two contact members are locked to the insulating member in a position engaged in said insulating member by said snap flaps or tabs .

48. Method for assembling or coupling contact members on contact terminals of a connector according to one or more of the preceding claims, characterized by following steps: assembling is carried out in sequence and in a separate manner for the two contact members and the insulating member, in a first step by applying the annular contact member on the cylindrical contact terminal and then by inserting above the annular contact member the insulating member till it is brought in stop abutment against the annular contact member, while as the last step the cup member is engaged on the enlarged head central terminal through the central hole of the insulating member of the annular contact member, till said cup contact member is in a stop engagement position on said terminal and simultaneously in a locking position in the insulating member.

49. Method according to claim 48, characterized in that the position of snap flaps or tabs with respect to the position of contact members in the condition engaged on the corresponding contact terminal and of complementary recesses engaging snap flaps or tabs on the insulating member with respect to the assembling posi- tion thereof on contact terminals and with respect to flaps or tabs snapping on contact members, preferably the relevant position of said snap flaps or tabs and engaging recesses with reference to the engagement direction is such that upon coupling condition of contact members on corresponding contact terminals, the two contact members are perfectly engaged in the insulating member in the locking condition inside said insulating member .

50. Method according to claims 48 or 49, charac- terized in that for the separation or uncoupling of contact members from contact terminals, that occurs in such a way that the three parts that is contact members and the insulating member remain joined together forming a kind of bipolar pipe plug.

51. Method according to one or more of claims 48 to 50, characterized in that a subsequent ^" coupling of contact members on corresponding terminals may occur at the same time in the assembled condition of the two contact members on the insulating member as bipolar 5 plug.

52. Connector according to one or more of the preceding claims 1 to 47, characterized in that it is a monopolar connector comprising only the cup shaped contact member (4) and the insulating member (5) .

LO

53. Connector according to one or more of the preceding claims 1 to 47 and 52, characterized in that the insulating member (5) is provided with a radial extension forming a radial channel (905) for housing a radial extension (104) of the cup shaped contact member

L5 (4) and the cable mechanically connected and electrically connected to the said radial extension (104) of the cup shaped contact member (4) , the said channel (905) being provided at its radially outer end with elastic means for retaining the cable inside the said

20 channel (905) .

54. Connector according to one or more of the preceding claims 1 to 47 and 52 and 53, characterized in that the annular contact member (3) is pressed against an annular head surface of an annular contact terminal 5 (2) by means of the insulating member (5) , the means for retaining the insulating member (5) in this position being provided on the insulating member (5) itself and on the cup shaped contact member (4) .

0