DESCRIPTION

The present invention relates to a system for the connection between a standard thermostat and one or more candle resistances, by plug-in coupling of respective fastons.

The invention falls within the sector of heater appliances, in particular electrically-powered storage water heaters (a sector that shall be referred to exclusively hereinafter, for clarity of description and consistency with what shown in the annexed figures), but it is applicable to any household appliance in which electric heating elements and safety and temperature regulation thermostats are used. Even more particularly, the object of the present invention relates to a specific type of electrical resistance, known as “candle resistance” and long been used in the sector: such type of resistance is part of the family of “dry heating” elements, i.e. electrical resistances not operating in direct contact with the liquid to be heated but they operate in air, inside a special containment sheath. More in detail, the candle resistance consists of a resistive filament contained in a metal tube (hereinafter referred to as “armor") folded onto itself, to form two parallel branches, by means of a hydraulic press, also adapted to flatten the section thereof except the end portions, which remain of circular section and spread apart because not introduced into such hydraulic press. Figs. 1.A and 1.B help clarify the configuration of a candle resistance currently in use, as well as show a connection system between such resistance R and a standard thermostat T according to the current state of the art, whose respective armor and rod A are housed inside containment sheaths GR and GT supported by the flange F of the water heater.

As mentioned, the candle resistance R comprises a resistive filament FR inserted in a folded armor, delineating two spread apart ends MR’, from which the two terminals of said resistive filament FR protrude (hereinafter referred to as “pins FR”): the application of insulating inserts IS and the sufficient spatial distance, deriving from the spreading of the two ends MR’ of the armor, avoid risks of short circuit due to contact between such pins FR.

Such candle resistance R is located inside the containment sheath GR, substantially for the entire length of its armor, except for such spread apart ends MR’, which remain below the flange F.

According to the variant of the prior art of Figs. l.A and l.B, the electrical connection between said candle resistance R and said thermostat T takes place by means of a special connection wiring (not shown in figure) between fastons CR, applied on the pins FR, and fastons CT of said thermostat T.

Alternatively, the electrical contact between the two components is ensured with a direct mechanical constraint (typically bolting with nuts and washers) of the pins FR of the candle resistance R on the fastons CT of the thermostat T.

Both connection methods just mentioned have drawbacks related to the number of components to be assembled, with an increase in costs for raw materials and labour and greater possibility of failures, for example associated with deterioration due to the Joule effect of the electrical wiring or mounting errors. The purpose of the present invention is to obviate such kind of drawbacks, by providing a different electrical connection method between the candle resistance and thermostat, which allows the assembly operations of the system to be simplified and the risks of malfunction to be reduced.

A further object, at least of some variants of the invention, lies in the possibility of providing a different configuration of the candle resistance, with positive effects on the heating capacity and on the manufacturing costs.

Another object, at least of some variants of the invention, consists in indicating means and methods for coupling between a plurality of candle resistances and a thermostat. These and other objects, which shall appear clearly hereinafter, are achieved with a connection system according to claim 1.

Other objects may also be achieved by means of the additional features of the dependent claims.

Further features of the present invention shall be better highlighted by the following description of some preferred embodiments, in accordance with the patent claims and illustrated, by way of a non-limiting example, in the accompanying drawing tables, in which:

- Figs. l.A and l.B depict a connection system between a candle resistance R and a thermostat T in accordance with a method of the prior art as previously described, according to a side view and a perspective view, respectively;

- Fig. 2 is a side view of the connection system between a candle resistance R and a thermostat T in accordance with a preferred variant of the invention; - Fig. 3 shows a perspective exploded view of the connection system of Fig. 2;

- Figs. 4. A and 4.B show, respectively, according to a perspective exploded view and a side exploded view, the connection system between a candle resistance R and a thermostat T according to a further variant of the invention;

- Fig. 5 is a perspective exploded view of the connection system between a plurality of candle resistances R and a thermostat T according to a variant of the invention;

- Fig. 6 is a plan view of the system shown in Fig. 5; - Figs. 7. A and 7.B show perspective exploded views of the connection system between a plurality of candle resistances R and a thermostat T according to another variant of the invention;

- Fig. 8 is a perspective view of the connection system between a plurality of candle resistances R and a thermostat T according to a further variant of the invention;

- Fig. 9. A is a perspective exploded view of the connection system between a plurality of candle resistances R and a thermostat T according to another variant of the invention;

- Fig. 9.B is a variant of the pins of the candle resistance R for the connection to the thermostat T according to the invention shown in the variant of Fig. 9. A.

The features of a preferred variant of the invention are now described using the references in the figures and with specific reference to the scope of application of the storage water heaters. It is noted that the above figures, although schematic, reproduce the elements of the invention according to proportions among their spatial dimensions and orientations that are compatible with a possible embodiment.

With reference to Figs. 2 and 3, R indicates a candle resistance (hereinafter abbreviated to “resistance R”) that, according to a preferred variant of the invention, has the ends MR of the armor no more spread apart, as seen so far in the prior art, but close and parallel.

Such new geometrical configuration of the resistance R is obtained through an extremisation of the pressing step of its armor, which is subjected to flattening of the section for the entire length of both branches, however, without affecting the electrical insulation and rigidity properties between said armor and the two pins FR.

As per prior art, the ends are in fact always sealed by means of heat-shrink material or by silicone sealant; alternatively or in addition to such standard materials, the application of an insert 4 in the form of a closing cap and spacer, of insulating material, may be provided, still having the function of ensuring electrical insulation of the end of the resistance R and of avoiding any contact between the pins FR.

The resistance R thus obtained has the practical advantage of being able to be entirely inserted (or, however, for a greater stretch with respect to the standard resistance R with spread apart ends MR’) in the containment sheath GR supported by the flange F of the water heater: therefore, also the height mechanical footprint of the thermostat T will be reduced, as well as the pins FR will be in a further position from the possible cap of the water heater accessible to the end user.

According to a preferred variant of the invention, the electrical connection system between the mentioned resistance R and thermostat T comprises a pair of metal connectors 1 (hereinafter “connectors 1”), constrained to the pins FR and having a suitable shape such as to allow the plug-in coupling with respective fastons CT of said thermostat T.

As shown in Fig. 3, each of said connectors 1 comprises:

- a first arm 1.1 developing orthogonally outwards with respect to the longitudinal axis of the resistance R, said arm 1.1 having:

- the proximal end 1.10 adapted to be constrained to the pin FR (typically by welding, but any other constraining methodology may be used) and

- the distal end 1.11 connected to a second arm 1.2,

- said second arm 1.2 developing substantially orthogonally with respect to said first arm 1.1 and having the distal end 1.20 connected to a female faston l.CR,

- said female faston l.CR directed downwards, orthogonally to said second arm 1.2.

In conclusion, the pair of connectors 1, so shaped and constrained to the pins FR of the resistance R results in the location of the relative female fastons l.CR of said resistance R in a position perfectly in axis with the male fastons CT of the thermostat T, thus allowing an axial insertion for the reciprocal plug-in coupling without additional means (such as wiring or mechanical fixing means, provided so far in the systems of the prior art).

According to a preferred variant of the invention and illustrated in Figs. 4. A and 4.B, the connection system is integrated with the presence of a rigid support 2, adapted to act as a protection element of said connectors 1 and as a contrast to the insertion/removal force with the fastons CT of the thermostat T.

Said rigid support 2 is made of dielectric material, suitable for supporting the mechanical stresses deriving from the coupling and uncoupling steps of the female fastons l.CR of the resistance R with the male fastons CT of the thermostat T, as well as withstanding the high operating temperatures.

Preferably, said material consists of a thermoplastic material such as polyphenylsulfone PPS (for example, Fortran), that proved to be ideal for injection co-moulding of the rigid support 2 with such connectors 1.

As an alternative to co-moulding, the rigid support 2 may be moulded separately and subsequently associated to the connectors 1.

Such rigid support 2 comprises a plate-like body having:

- holes 2.1 (slots or openings) for the insertion of the two pins FR of the resistance R,

- seats (not visible in the figure) incorporating the arms 1.1 and 1.2 of the connectors 1,

- at least one hole 2.2 for the fixing of the flange F, with known constraining means or in addition to said at least one hole 2.2, the fixing of such rigid support 2 to said flange F may take place by means of jointing means and/or mechanical hooks,

The rigid support 2 thus made, co-moulded on the connectors 1 or associated thereto as a separate element, also acts as protection for the arms 1.1 and 1.2 during the transport steps of the resistance R.

As said above, the provision of at least one hole 2.2 or jointing means and/or mechanical hooks of equal function, enables such rigid support 2 to stably secure the herein described connection system to flange F, even in the event that the “resistance R/thermostat T” assembly is positioned horizontally or with inclinations that do not allow a stable and firm support on said flange F: such fixing opportunity provides for, in conclusion, the impossibility of locking the candle resistance R to flange F by acting with direct mechanical constraints on the ends MR of the armor thereof, which do not protrude any more from the containment sheath GR supported by flange F of the water heater, unlike the standard known so far in the prior art.

In accordance with a variant of the invention, the system, object of the present invention, may provide for, in addition to the presence of the above described rigid support 2, also the addition of a further protective element 3 in insulating material, specifically aimed to the protection of the female fastons l.CR of the connectors 1.

Such protective element 3, as depicted in Figs 4. A and 4.B, comprises a pair of side shells 3.1 wherein said female fastons l.CR are inserted, which are therefore protected and axially guided for the plug-in coupling with the fastons CT of the thermostat T.

Further, said protective element 3, prevents accidental contacts between the female fastons l.CR and the other parts under voltage of the system, a particularly useful quality in the maintenance and technical assistance step of the water heater.

Therefore, the connection assembly just described, comprising the connectors 1 with relative rigid support 2 (and, possibly, the protective element 3 according to a variant of the invention), realises an electrical connection means of the resistance R in which its female fastons l.CR are located vertically in axis with the male fastons of the thermostat T to which they must be connected, enabling quick and reliable plug-in coupling, with significant advantages with respect to the current connections by wiring, in terms of increased safety, reduction of components and costs, possibility of using female fastons l.CR and male fastons CT of standard measures, or, however, having any shape for a mutual coupling to one another. What described so far relates to a plug-in connection system between a resistance R and a thermostat T, as shown in the figures from Fig. 2 to Fig. 4.B; in the figures from Fig. 5 to Fig. 9.B, similar connection systems are shown instead, however, provided with additional and/or slightly different means for using the connection system in case there is a need to use more than one resistance R.

According to the variant shown in figs. 5 and 6, the first resistance R comprises the connection system described above, coupling in a plug-in manner with the thermostat T; the one or more resistances R2, R3, Rn-th ... subsequent to the first resistance R, are instead electrically connected with a modular element system BB (hereinafter, each of which is called “bail BB”), located one following the other depending on the positioning of said one or more additional resistances R2, R3, Rn-th to be installed in the product and to be inserted in their respective containment sheaths GR2, GR3, GRn-th, supported by the flange F.

Each of such bails BB may comprise a rigid support BB.l in insulating material, preferably co-moulded on (or moulded separately and subsequently associated with) a pair of metal connectors B (hereinafter “connectors B”) having first connection means B.C1 adapted to come into contact with the pins of the previous resistance and second connection means B.C2 shaped so as to be in contact with the pins of the additional resistance.

Preferably, each rigid support BB.l further comprises a pair of side appendices BB.2 for fixing to the flange F, by means of common constraining means.

For greater clarity, taking as a reference what is shown in Figs. 5 and 6 that show a variant of the connection system with three resistances R, R2 and R3, the system has the following configuration:

- the first resistance R comprises the connection system consisting of the pair of connectors 1 and the rigid support 2 (plus, possibly, the protective element 3, not shown in Figs. 5 and 6), to couple in plug-in mode with the thermostat T (also not shown in such figures);

- the second resistance R2 is electrically connected thanks to the bail BB, the pair of connectors B whereof has first connection means B.C1 in contact with the pins FR of such first resistance R and second connection means B.C2 in contact with the pins of said second resistance R2;

- similarly, the third resistance R3 is electrically connected by means of a further bail BB, advantageously identical to the previous one, the pair of connectors B whereof has first connection means B.C1 in contact with the pins of said second resistance R2 and second connection means B.C2 in contact with the pins of such third resistance R3.

Similarly to the rigid support 2, therefore, also the rigid support BB.l of such one or more braces BB acts as a dielectric element (for the correct insulation among the phases of the resistances R, R2, R3, Rn-th) and as a mechanical abutment (to withstand the stresses caused by the insertion/disconnection steps with such resistances R, R2, R3, Rn-th, especially in the case of maintenance and technical assistance interventions), incorporating the pair of connectors B. Like said rigid support 2, the aforementioned rigid support BB.l of the bail BB is preferably made of insulating material such as polyphenylsulfone PPS (for example Fortran), co-moulded to its connectors B or constrained thereto subsequently to moulding.

According to the variant illustrated in Figs. 7. A to 9.B it can also be envisaged that the plug-in connection system between a plurality of candle resistances R and a thermostat T takes place with a single bail BB, which comprises:

- a single pair of connectors B, developing lengthwise so as to comprise:

- a proximal end represented by the female fastons l.CR constrained to the pins FR of the first resistance R, said female fastons l.CR being shaped similarly to the female fastons already described for the other variants and adapted, therefore, to be placed perfectly in axis with the male fastons CT of the thermostat T for their mutual plug-in coupling,

- as many connection means B.C1/B.C2 as the candle resistances R, adapted to electrically connect with the pins of each of said resistances R, R2, R3, Rn-th,

- a single rigid support BB.l in thermoplastic material, preferably co moulded on (or moulded separately and subsequently associated with) said single pair of connectors B and (like the rigid support 2 of the variant with single resistance R or the rigid support BB.l of the variant of Figs. 5 and 6) adapted to act as a dielectric element (for the correct insulation among the phases of the resistances R, R2, R3, Rn-th) and as a mechanical abutment (to withstand the stresses caused by the insertion/disconnection with such resistances R, R2, R3, Rn-th, especially in case of maintenance and technical assistance interventions). Preferably said rigid support BB.l comprises at least one hole BB.2 (slot or opening) for fixing to the flange F, by means of common constraining means; advantageously, said at least one hole BB.2 may consist of one or more pairs of side holes BB.2, the term “holes” always meaning any opening or coupling means that allows constraining said rigid support BB.l to the aforementioned flange F.

As said, the aforementioned rigid support BB.l of said single bail BB is always preferably made of insulating material such as polyphenylsulfone PPS (for example Fortran), co-moulded to its connectors B or constrained thereto subsequently to moulding.

In the variant of Figs. 7. A and 7.B, said connection means B.C1/B.C2 are represented by springs for contact with the pins of the resistances R, R2, R3, Rn- th; in the variant of Fig. 8, on the other hand, such connection means B.C1/B.C2 consist of metal terminals equipped with tightening screws with said pins of the resistances R, R2, R3, Rn-th; in the variant of Fig. 9. A, finally, such connection means B.C1/B.C2 consist of through holes with fixing means (such as, for example, screws and washers) to the pins (possibly also threaded, see the variant of Fig. 9.B) of such resistances R, R2, R3, Rn-th.

However, such connection means B.C1/B.C2 are only non-limiting examples, as they can consist of any metal means that ensures the electrical connection with the pins FR of said resistances.

In each of the cases shown in the variants of Figs. 7. A to 9.B, the connection system for multiple candle resistances R may comprise a single rigid support BB.l incorporating the pair of connectors B, (although it is not shown in Figs. 8 and 9. A), adapted to act as a protection element of said connectors B and as a contrast to the coupling/uncoupling force of the female fastons l.CR of the resistance R with the male fastons CT of the thermostat T.

However, in a minimal and less effective version of the invention according to the variants of Figs. 5 to 9.B, such rigid support BB.l may also be absent; where present, on the other hand, the provision of at least one hole BB.2 (advantageously consisting of one or more pairs of side holes BB.2, the term “holes” always meaning any opening, slot or coupling means that allows constraining said rigid support BB.l to flange F), enables such rigid support BB.l to stably secure the herein described connection system to the aforementioned flange F, even in the event that the “resistance R/ thermostat T” assembly is positioned horizontally or with inclinations that do not allow a stable and firm support on said flange F: such fixing opportunity ultimately compensates for the impossibility of locking the candle resistance R to the flange F by acting with direct mechanical constraints on the ends MR of its armor, which no longer protrude from the containment sheath GR supported by the flange F of the water heater, unlike the standard known so far in the prior art. From the above description, the advantages achievable with the present invention appear clear, the first of which relates to the possibility of achieving a plug-in coupling between the resistance R and the thermostat T without the aid of the wiring used so far, subject to structural weaknesses and unreliability over time, or of the direct mechanical constraint, which causes an increase in costs for raw materials and labour.

The connection system claimed herein extends the application of standard type thermostats T to the kind of candle resistances R, enabling the use of standard sized female fastons l.CR on the latter, intended to be coupled in plug-in mode with the male faston CT of the thermostat, also of standard size.

Furthermore, for the same reasons, it is also possible to use fully electronic thermostats; the plug-in coupling of the thermostat T immediately close to the candle resistances R also makes the tripping of the mechanical safety of such thermostats more reactive in the event of overtemperatures, eliminating the delays and intrinsic weaknesses of the connection with wiring or with direct mechanical constraint.

It is clear that several variants of the connection system described above are possible for the man skilled in the art, without departing from the novelty scopes of the inventive idea, as well as it is clear that in the practical embodiment of the invention the various components described above may be replaced with technically equivalent ones.

For example, it is possible to provide that the pair of connectors 1 has a different shape than that described for the preferred variant of the invention, providing for example first or second arms 1.1, 1.2 with different spatial profile or development, it being understood the positioning of the female fastons l.CR according to the correct vertical axis with the male fastons CR of the thermostat T to which the must be coupled in plug-in mode.

According to a less efficient variant of the invention, it is also possible to provide for the application of the connection system described above also to candle resistances R shaped according to the prior art, i.e. having the ends MR’ of the armor spread apart and not close and parallel.

In such case, the connectors 1 will be equipped with first arms 1.1 with less longitudinal development, to compensate for the distance between the pins FR already resulting from the spreading of such ends MR’; likewise, the pair of connectors B of the one or more bails BB will have the first and second connection means B.C1/B.C2 more distantly spaced, in axis with the pins of the resistances with which they must come into contact.