Multiple-pole switch and/or circuit breaker for low voltage

Description

Object of the Invention

[0001] The invention relates to a switch and/or circuit breaker incorporating various cut-off poles that can be connected in series to reduce the cut-off voltage.

[0002] An object of the invention is to provide a multiple-pole switch in which several poles are more effectively and more safely connected in series, preventing excessive overheating of the components and possible switch failures.

[0003] The invention essentially applies to switches for low voltage with selfcleaning blade contacts, although it can also apply to any other type of switch, such as for example cam switches.

Background of the Invention

[0004] Switches of any type or model are devices used to connect and disconnect a load from an electric power source. These switches are based on applying an external force which moves several moving contacts with respect to other fixed contacts, such that when the circuit is to be closed, the moving contacts come into contact with the fixed contacts, forming the connection between load and power source, and causing the corresponding installation to start operating.

[0005] The opposite process corresponds to the movement of the moving contacts with respect to the fixed contacts, such that these moving contacts move away from the fixed contacts, causing the circuit to open and therefore isolating the load from the power source, and as a result the installation stops.

[0006] An electric arc causing wear in the contacts is formed during the opening and closing process. To increase the opening and closing power of the contacts, contact reliability must be assured, and to do so it is necessary to reduce the effects of the electric arc on said contacts because the less wear that occurs in them, the more durable they will be or the greater closing and cut-off power they will withstand.

[0007] This functionality is applied both for alternating current and direct current, with the difference that in direct current, the wave does not cross zero, i.e., it is not cancelled, and therefore the arc extinction is much more complicated. Therefore, in the applications of direct current and as the voltage is increased, is necessary to connect various contacts in series for splitting the arc power, and such that a voltage smaller than the total working voltage and which will be proportional to the number of poles in series can be cut-off in each contact.

[0008] As shown in Figure 1 flat bars screwed to connecting contacts of the switch which acts as bridges between the contacts are currently used for connecting various contacts in series for splitting the arc power. Conventionally, such switches, for the case of four pole switches, is formed by a first group of fixed contacts (2,3, 4 and 5), a second group of fixed contacts (2',3', 4' and 5'), and a group of moving contacts (2", 3", 4", and 5"), able to move simultaneously between an electrical cut-off position and an electrical closure position in which, for each pole, a moving contact electrically connects a fixed contact of the first group with a fixed contact of the second group.

[0009] A bridge or flat bar (1, 11, 12) is screwed to the respective fixed contacts belonging to two consecutive poles for connecting two poles in series, using to that end screws (10) passing through corresponding holes made in the contacts and flat bar.

[0010] This conventional solution implies many drawbacks:

First, the connection between terminals and flat bar are points with increase electrical resistance due to the electrical resistance per se through the gap of the material in that of the attachment between the three parts, and therefore are points which cause a temperature increase,

Since it is a threaded attachment, it can become loose with time due to temperature changes and vibrations. The threaded attachment requires verifying the coupling torque and its assembly because if said torque is not applied correctly damage can be produced by the effect of temperature increase due to a poor contact, whether due to the fact the torque is insufficient and the pressure in the connection area is insufficient or due to an excess of torque and the thread is destroyed or damaged, thereby also causing a similar defect of lack of pressure in the connection area.

[0011] The bridge installation operation requires a certain amount of time, whether at the factory or on site assembly, so there is extra cost involved in the installation.

[0012] All threaded attachment is exposed to the environment, and therefore withstanding the obvious cyclic environmental conditions, it undergoes expansions and contractions, and in order to prevent these deformations from entailing a failure in the connection area over time the installation must be periodically maintained for verifying and assuring that all the attachments are maintained within the corresponding safety parameters. In summary it is necessary to prevent a poor contact, the consequence of which is overheating and subsequently a fire and destruction of the equipment and installation itself, as well as maintaining the safety of the personnel.

[0013] British patent GB-22309001A describes an electrical distribution board equipped with disconnectors.

[0014] German Patent DE-10207539 refers to a switch for remote controls which has circuit board with conducting tracks, thrust part with contact parts for tracks, covering housing and elastic intermediate body between thrust element.

[0015] The Us Patent US-4090293 refers to a method for manufacturing an electrical component comprising a connection tag.

[0016] British patent GB-926705 refers to an isolating electric switch.

Description of the Invention

[0017] The present invention completely and satisfactorily solves the aforementioned problem by means of the subject-matter defined in the attached independent claims.

[0018] The invention relates to a low voltage switch and/or circuit breaker, i.e., to a switch which in addition to performing the opening (disconnection) and making the connection, also has isolating capacity, such that once the opening is performed, the fixed contact and the moving contact are at a sufficient distance for assuring the disconnection preventing the electric arc.

[0019] In this description of the invention, the term switch or switch device must be understood as a device with the function of a switch, or a device with the function of a switch and circuit breaker, or a circuit breaker device.

[0020] The switch object of the invention is characterised by being provided with a multiple terminal or contact, consisting of a single piece configured for making up two or more contacts having different poles of the switch.

[0021] The advantage of removing the outer screwed bridges connecting two contacts in series and thus preventing all the drawbacks of heating and maintenance described above is obtained by means of this multiple contact formed by an integral piece, i.e., a single body, because the electric current flows through an integral piece, i.e., through a single body of continuous material and same section, instead of through the screwed bridge which has material interruptions and section changes, different material resistivity, etc.

[0022] More specifically, the invention relates to an electric breaker switch having two or more poles, comprising first and second groups of fixed contacts, and a group of moving contacts able to move between an electrical cut-off position and an electrical closure position in which, for each pole, a moving contact electrically connects a fixed contact of the first group with a fixed contact of the second group. The switch is characterised in that at least two fixed contacts of the same group of contacts are consist of or are part of an integral piece made of a suitable conductor material connecting the poles of the switch associated with said contacts in series.

[0023] Each pole of the switch is formed by a pair of fixed contacts and a moving contact connecting or disconnecting them.

[0024] Said integral piece is configured such that a first part determining a first fixed contact of one pole, a second part determining a second fixed contact, and a third part connecting with both fixed contacts is distinguished therein.

[0025] The invention also relates to a method of manufacturing an electric breaker switch device having two or more poles, which is characterised by assembling at least one multiple contact like the one described above in a same type of casing. Many configurations of the poles of switch are thus obtained in a simple and economical manner using one and the same type of casing or base, and one and the same type of multiple contact by simply placing this multiple contact in different positions of the casing.

Description of the Drawings

[0026] To complement the description which is being made and for the purpose of aiding to better understand the features of the invention according to a preferred practical embodiment thereof, a set of drawings is attached as an integral piece of said description in which the following has been depicted with an illustrative and non-limiting character:

Figure 1 shows a four pole switch of the state of the art where drawing (a) is a perspective and exploded view, drawing (b) is a top plan view, and drawing (c) is a cross-section view according to lines A-A of drawing (b), and drawing (d) is a top plan view of the inside of the device, i.e., without the upper part of the casing.

Figure 2 shows in three plan views the operation of electrically opening and closing the inside of a multiple-pole switch of the state of the art, where drawing (a) shows the closure position of the contacts (electric connection), drawing (b) shows an intermediate position with the moving slider, and drawing (c) shows the open position of the contacts (electric disconnection).

Figure 3 shows a depiction similar to that of Figure 1 but of a preferred embodiment of the multiple-pole switch according to the present invention.

Figure 4 shows a depiction similar to that of Figure 3 of another embodiment of the multiple-pole switch according to the present invention.

Figure 5 shows a depiction similar to that of Figure 3 of another embodiment of the multiple-pole switch according to the present invention.

Figure 6 is a depiction similar to that of Figure 3 of another embodiment of the present invention.

Figure 7 is a depiction similar to that of Figure 3 of another embodiment of the present invention.

Preferred Embodiment of the Invention

[0027] Figure 3 shows an embodiment of a switch device according to the invention, in this case a four pole switch with two multiple contacts. Each pole of the switch is formed by a fixed contact of a first group of fixed contacts (2, 3, 4 and 5), a second fixed contact of second group of fixed contacts (2', 3', 4', and 5'), and a moving contact (2", 3", 4", and 5") able to move between an electrical cut-off position in which it is not in contact with the fixed contacts (corresponding to the position depicted in Figure 2c) and therefore making current circulation impossible, and an electrical closure position in which it electrically connects the two fixed contacts with which it is associated (corresponding to the position depicted in Figure 2a).

[0028] The moving contacts (2", 3", 4", and 5") are assembled equidistant to one another in a shuttle or slider (9) made of insulating material such that the moving contacts move together and simultaneously. The switch further comprises a casing (7) made of an electrically insulating material, inside which at least part of the fixed contacts, and the slider (9) with the moving contacts are housed, and such that the fixed contacts of the same pole are facing one another in pairs.

[0029] The slider (9) can move linearly inside the casing between two end positions defined by the internal shape of the casing itself and is assembled between the two mentioned groups of fixed contacts such that it moves transversally with respect to them.

[0030] The casing is formed by a lower base (7b) and an upper base (7 a) coupled to one another, and with an opening through which an external control (8) is attached to the slider (9) to operate it manually. Alternatively, the slider can be moved, for example, by means of an automatic driving device.

[0031] The fixed contacts are assembled inside one of the parts of the casing, for example in the lower base (7b) by means of screws (13). The moving contacts (2", 3", 4", and 5") are in turn blades, i.e., they are made up of two pairs of overlapping flat bars (6,6') forming a space between them, inside which they are coupled to each fixed contact, such that each moving contact contacts the corresponding fixed terminal from the top and the bottom, as especially seen in Figure 1c. These moving contacts (2", 3", 4", and 5") are dual moving contacts because they are each made up of two pairs of connected flat bars (6,6'), where each pair is arranged to contact a fixed terminal of the same pole.

[0032] The switch incorporates a first integral piece (14) configured such that it determines at least two fixed contacts of a same group of contacts, specifically in view of Figure 3d, the first integral piece (14) has a first part (14a) determining a fixed contact (4) of a pole, a second part (14b) determining a second fixed contact (5) of another pole, and a third intermediate part (14c) connecting said first and second parts (a,b). Since the two fixed contacts (4, 5) are part of the same body or part, the poles associated with these terminals are connected in series, as seen in Figure 3d.

[0033] The switch of this preferred embodiment incorporates a second integral piece (15) identical to the first piece (14) but placed in the group of opposite fixed contacts, and forming the fixed contacts (2',3') corresponding to the other two poles of the switch, connecting them in series.

[0034] In this embodiment, the integral pieces (14,15) are U-shaped, where each arm corresponds to each of the fixed terminals. In other embodiments, the integral piece (14,15) can be formed to determine more than two fixed contacts, in which case it adopts an E shape or comb shape.

[0035] Preferably, the integral piece has a constant thickness throughout and is made of the same type of material as the rest of the conventional fixed contacts, preferably metal, and has the same thickness, whereby gaps in the section of the material or changes in electrical resistivity for current circulation is prevented.

[0036] As seen in Figure 3, the conventional fixed contacts (2,3,4',5') have the shape of a flat bar and part of the same protrudes outside the casing (7) to enable its electrical connection with the wiring of an external electrical installation in an already known manner, for example for closing or opening the current circulation between an electrical power source and a load.

[0037] The two integral pieces (14,15), which in this case are planar throughout, are completely housed inside the casing, which has the advantage that it cannot be touched by accident, i.e., there is no access to them and therefore the operator cannot have an electric or thermal accident. To that end, the casing is designed for a specific configuration of number and position of pieces (14,15).

[0038] Since these integral pieces (14,15) are internal pieces, they can reach a temperature higher than a bridge or an external terminal, whereby the switch is designed to work within the temperature limits established in the corresponding product regulations. Furthermore, the invention has provided an air chamber (16) in the casing for receiving part of the pieces (14,15) which, together with the walls made of insulating material forming the casing (7), provide a safe heat-electric insulation within the parameters established by the regulations.

[0039] Figure 4 shows a four pole switch similar to that of Figure 3, but in this embodiment, the integral pieces (14,15) are arranged in the same group of fixed contacts, so a configuration of switch different from that of Figure 3 is obtained in which the conventional fixed contacts were located on opposite sides of the casing, whereas in the switch of this Figure 4 the conventional fixed contacts are located on the same side of the casing.

[0040] Furthermore, in the embodiment of the invention of Figure 4, the integral pieces (14,15) are formed such that they have a bent portion (17,18) respectively determining an angle with respect to the rest of the part, in this case in a substantially orthogonal shape with respect to the rest of the part. The casing, specifically the lower base of the casing (7b) also has an air chamber (16) for housing, precisely those bent portions (17,18), the integral pieces (14,15), such that the pieces (14,15) are housed entirely inside the casing. Specifically, that bend is formed in the intermediate part (c) of the integral pieces (14,15), and has the effect or advantage of reducing the space occupied by the pieces (14,15) resulting in a more compact switch.

[0041] The preferred embodiment alternative of Figure 5 consists of a four pole switch similar to that of Figure 4, provided with two integral pieces (14,15) with bent portions (17,18), but located in groups of opposite fixed contacts and with the particularity that these bent portions (17,18) protrude outside the casing (7) so they are exposed. Optionally, the switch incorporates insulating covers (19,20) configured to enable it to be coupled to the casing (7) to cover the bent portions (17,18) respectively. The effect or advantage of this alternative with couplable covers is that switches can be manufactured using an already existing casing or a universal casing that works for many switch configurations , i.e., with various positions, number and type of integral pieces, and subsequently coupling the covers as deemed necessary to cover the parts protruding from the integral parts.

[0042] The embodiment of Figure 6 is similar to that of Figure 5, but in this case the integral pieces (14,15) are completely planar and protrudes out of the casing, such that the covers (19,20) are of suitable size and shape for enclosing the protruding portions of the pieces (14,15).

[0043] Alternatively, a universal casing can be provided for receiving several integral pieces (14,15) with bent portions (17,18), placed in different positions whether on a single side or on both sides of the device, as has been depicted in Figure 7. The casing is sized for receiving many integral pieces, on both sides of the slider, for which it has respective grooves (16,16'), one on each side of the casing for receiving the bent portions (17, 18) of the integral pieces. In other words, the same casing can house one or several integral pieces in any position inside the casing or can even be used for applications of alternating current which do not incorporate integral pieces

[0044] The embodiments of Figures 3 to 6 can be combined with one another resulting in switches with one or more multiple contacts, i.e., with two or more integral pieces having two or more poles, placed in one or the two groups of fixed contacts irrespectively, said parts being able to be internal or external planar parts or with a bent.

[0045] The invention is also applicable to switches of another type and with a greater or lesser number of poles.

[0046] Depending on the needs of each application, in the manufacturing of the switch one or more integral pieces are installed in positions selected for connecting several poles in series, obtaining the configurations for four poles such as for example the following:

• 4+0. All the poles are attached in series, such that it would be connected to the power cable at one end and to the load at the other end, i.e., the four poles are attached and would be for example the positive cable. The circuit of the negative cable would not be able to be opened and closed and, therefore, it would be a cable which is on the outside of the switch (i.e., 0 of 4+0).
• 3+1. Three poles in series for making up for example the circuit of the positive and a pole for the circuit of the negative which, in this case, would also be able to open and close the circuit.
• 2+2. Both the circuit of the positive and that of the negative would comprise two poles in series.

Claims

1. Electric switching device having two or more poles, comprising:

first (2,3,4,5) and second (2',3',4',5') groups of fixed contacts, and a group of moving contacts (2",3",4",5") configured for connecting the fixed contacts of the same pole,

a slider (9) made of an insulating material arranged in between the first (2,3,4,5) and second (2',3',4',5') groups of fixed contacts, and wherein the moving contacts (2",3",4",5") are assembled in the slider (9) which is arranged to move linearly between an electrical cut-off position and an electrical closure position, such as in the electrical closure position, for each pole, a moving contact (2",3",4",5") electrically connects a fixed contact of the first group (2,3,4,5) with a fixed contact of the second group (2',3',4',5') of fixed contacts,

a casing (7) made of an electrically insulating material, inside which the moving contacts and at least part of the fixed contacts are housed, and such that the fixed contacts of the same pole are facing one another in pairs,

characterized in that at least two fixed contacts of the same group of fixed contacts are part of an integral piece (14) formed as a single body made of an electrically conductive material,

and wherein said integral piece (14) comprises a first part (14a) determining a fixed contact of one pole, a second part (14b) determining a second fixed contact of another pole, and a third part (14c) connecting said first and second parts (14a,14b),

such as the poles of the switch associated with the fixed contacts formed with the integral piece (14) are connected in series.

2. Device according to claim 1, characterized in that the integral piece (14) is U-shaped.

3. Device according to claim 1, characterized in that the integral piece (14) is E-shaped.

4. Device according to any of the preceding claims, characterized in that the integralpiece (14,15) is substantially planar.

5. Device according to claim 1, characterized in that a portion (17,18) of the third part of the integral piece (14,15) is bent forming an angle with respect to the rest of the integral piece.

6. Device according to any of the preceding claims, characterized in that the integral piece (14,15) has a constant thickness throughout.

7. Device according to claim 1, characterized in that it comprises at least one integral piece (14,15) housed in its entirely inside the casing (7).

8. Device according to claim 1 or 6, characterized in that it comprises at least one integral piece (14,15) having an inner part housed inside the casing (7), and another outer part projecting outside the casing (7).

9. Device according to claim 8, characterized in that it further comprises at least one cover (19,20) made of an insulating material coupled to the casing (7), such that the outer part of the integral piece is housed inside said cover.

10. Device according to claim 5, characterized in that the casing is sized for housing several integral pieces (14,15) with bent portions (17, 18) and internally has grooves (16,16') inside the casing (7) where the bent part of the integral pieces can be housed.

Ansprüche

1. Elektrische Schaltvorrichtung mit zwei oder mehr Polen, umfassend:

erste (2,3,4,5) und zweite (2',3',4',5') Gruppen fester Kontakte und eine Gruppe beweglicher Kontakte (2",3",4",5"), eingerichtet zum Verbinden der festen Kontakte des gleichen Pols,

einen Schieber (9), hergestellt aus einem isolierenden Material und angeordnet zwischen den ersten (2,3,4,5) und zweiten (2',3',4',5') Gruppen fester Kontakte, und wobei die beweglichen Kontakte (2",3",4",5") im Schieber (9) eingesetzt sind, welcher eingerichtet ist, sich linear zwischen einer elektrischen Unterbrechungsposition und einer elektrischen Schließposition zu bewegen, sodass in der elektrischen Schließposition für jeden Pol ein beweglicher Kontakt (2",3",4",5") mit einem festen Kontakt der ersten Gruppe (2,3,4,5) und mit einem festen Kontakt der zweiten Gruppe (2',3',4',5') fester Kontakte verbunden wird,

ein Gehäuse (7), hergestellt aus einem elektrisch isolierenden Material, innerhalb dessen die beweglichen Kontakte und zumindest ein Teil der festen Kontakte angeordnet sind, und zwar so, dass die festen Kontakte des gleichen Pols einander paarweise zugewandt sind,

dadurch gekennzeichnet, dass zumindest zwei feste Kontakte der gleichen Gruppe fester Kontakte Teil eines integralen Bauteils (14) sind, welches als ein einzelner Körper, hergestellt aus einem elektrisch leitenden Material, geformt ist,

und wobei besagtes integrales Bauteil (14) einen ersten Teil (14a), der einen festen Kontakt eines Pols definiert, einen zweiten Teil (14b), der einen zweiten festen Kontakt eines anderen Pols definiert, und einen dritten Teil (14c), der besagte erste und zweite Teile (14a, 14b) verbindet, umfasst,

sodass die Pole des Schalters, die den mit dem integralen Bauteil (14) geformten festen Kontakten zugeordnet sind, in Serie verbunden sind.

2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass das integrale Bauteil (14) U-förmig ist.

3. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass das integrale Bauteil (14) E-förmig ist.

4. Vorrichtung nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass das integrale Bauteil (14,15) im Wesentlichen eben ist.

5. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass ein Abschnitt (17,18) des dritten Teils des integralen Bauteils (14,15) gebogen ist, um gegenüber dem Rest des integralen Bauteils einen Winkel zu bilden.

6. Vorrichtung nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass das integrale Bauteil (14,15) durchweg eine konstante Dicke hat.

7. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass sie zumindest ein integrales Bauteil (14,15), dass in Gänze [assumption: it should read "entirety" instead of "entirely" in claim 7] innerhalb des Gehäuses (7) angeordnet ist, umfasst.

8. Vorrichtung nach Anspruch 1 oder 6, dadurch gekennzeichnet, dass sie zumindest ein integrales Bauteil (14,15) umfasst, das einen inneren Teil, der innerhalb des Gehäuses (7) angeordnet ist, und einen äußeren Teil, der aus dem Gehäuse (7) hervorragt, umfasst.

9. Vorrichtung nach Anspruch 8, dadurch gekennzeichnet, dass sie weiter zumindest eine Abdeckung (19,20) umfasst, welche aus einem isolierenden Material hergestellt ist, welches an das Gehäuse (7) gekoppelt ist, sodass der äußere Teil des integralen Bauteils (14,15) innerhalb der Abdeckung (19,20) angeordnet ist.

10. Vorrichtung nach Anspruch 5, dadurch gekennzeichnet, dass das Gehäuse (7) so bemessen ist, dass es mehrere integrale Bauteile (14,15) mit gebogenen Abschnitten (17,18) aufnehmen kann, und innen Vertiefungen (16,16') hat, wo der gebogene Teil der integralen Bauteile (14,15) aufgenommen werden kann.

Revendications

1. Dispositif de commutation électrique possédant deux, ou plus, pôles, comprenant :

des premier (2, 3, 4, 5) et second (2', 3', 4', 5') groupes de contacts fixes, et un groupe de contacts mobiles (2'', 3'', 4'', 5'') configurés pour connecter les contacts fixes du même pôle,

un coulisseau (9) fait d'un matériau isolant agencé entre les premier (2, 3, 4, 5) et second (2', 3', 4', 5') groupes de contacts fixes, et dans lequel les contacts mobiles (2'', 3'', 4'', 5'') sont assemblés dans le coulisseau (9) qui est agencé pour se déplacer linéairement entre une position de coupure électrique et une position de fermeture électrique, de telle sorte que, dans la position de fermeture électrique, pour chaque pôle, un contact mobile (2'', 3'', 4'', 5'') connecte électriquement un contact fixe du premier groupe (2, 3, 4, 5) à un contact fixe du second groupe (2', 3', 4', 5') de contacts fixes,

un boîtier (7) fait d'un matériau électriquement isolant, à l'intérieur duquel les contacts mobiles et au moins une partie des contacts fixes sont logés, et de telle sorte que les contacts fixes du même pôle se fassent face par paires,

caractérisé en ce qu'au moins deux contacts fixes du même groupe de contacts fixes font partie d'une pièce monobloc (14) présentant la forme d'un corps unique fait d'un matériau électriquement conducteur,

et dans lequel ladite pièce monobloc (14) comprend une première partie (14a) déterminant un contact fixe d'un pôle, une deuxième partie (14b) déterminant un second contact fixe d'un autre pôle, et une troisième partie (14c) raccordant lesdites première et deuxième parties (14a, 14b),

de telle sorte que les pôles du commutateur associé aux contacts fixes formés avec la pièce monobloc (14) soient connectés en série.

2. Dispositif selon la revendication 1, caractérisé en ce que la pièce monobloc (14) présente une forme de U.

3. Dispositif selon la revendication 1, caractérisé en ce que la pièce monobloc (14) présente une forme de E.

4. Dispositif selon l'une quelconque des revendications précédentes, caractérisé en ce que la pièce monobloc (14, 15) est sensiblement plane.

5. Dispositif selon la revendication 1, caractérisé en ce qu'une portion (17, 18) de la troisième partie de la pièce monobloc (14, 15) est pliée, formant un angle par rapport au reste de la pièce monobloc.

6. Dispositif selon l'une quelconque des revendications précédentes, caractérisé en ce que la pièce monobloc (14, 15) présente une épaisseur constante dans sa totalité.

7. Dispositif selon la revendication 1, caractérisé en ce qu'il comprend au moins une pièce monobloc (14, 15) logée dans sa totalité à l'intérieur du boîtier (7).

8. Dispositif selon la revendication 1 ou 6, caractérisé en ce qu'il comprend au moins une pièce monobloc (14, 15) possédant une partie intérieure logée à l'intérieur du boîtier (7), et une autre partie extérieure faisant saillie à l'extérieur du boîtier (7).

9. Dispositif selon la revendication 8, caractérisé en ce qu'il comprend en outre au moins un couvercle (19, 20) fait d'un matériau isolant accouplé au boîtier (7), de telle sorte que la partie extérieure de la pièce monobloc soit logée à l'intérieur dudit couvercle.

10. Dispositif selon la revendication 5, caractérisé en ce que le boîtier est dimensionné pour loger plusieurs pièces monoblocs (14, 15) avec des portions pliées (17, 18) et possède intérieurement des rainures (16, 16') à l'intérieur du boîtier (7) où la partie pliée des pièces monoblocs peut être logée.

Drawing