Immersion heater with flame-arrester flange

Abstract

Immersion heater (5, fig. 1) comprising a resistive heating element (6, fig. 1), a flange 7 on which the resistive heating element is mounted, two distinct terminal lugs 10, 11 to be connected respectively to a power source supplying electrical current to electrically power the resistive heating element, the flange being provided with a screw thread to be screwed into a complementary screw thread provided on a tank of a domestic water heater, the flange comprising a plate 12 and a collar 8 which is such that the two terminal lugs extend beyond this plate, and such that the collar stands out from this plate, the collar having a length l2 relative to the plate that is greater than a distance d between a free end of the terminal lugs and a plane defining the opening of the collar. A kit comprising the immersion heater is also claimed.

Description

Title of the invention: Immersion heater with flame-arrester flange

[0001] The present invention relates to the field of water heater installations. In particular, the invention relates to a coupling for coupling an immersed heating element, also referred to as an immersion heater, to a tank forming a water heater and, more particularly, to a vertical electric water heater.

[0002] The invention also relates to a kit comprising such an immersion heater, a sealing gasket, means for attaching said immersion heater to a water heater tank and a cover intended to conceal the immersion heater coupled to the tank.

[0003] In order to power an electric water heater comprising a metal container forming a water tank, document GB2006584 discloses an electric heating element mounted on a wall of this tank such that the heating element is held in a threaded terminal block screwed to a mounting plate which is itself bolted to one wall of the tank.

[0004] Conventionally, this type of heating element comprises a hairpin-shaped metal sheath with a metal mounting element comprising two terminals extending from the terminal unit so as to be connected to a suitable power supply outside the tank.

[0005] US6123050 describes a sanitary-fluid heating device comprising a corrosion-resistant stainless steel housing. US4217483 describes a wiring unit for an electric immersion heater assembly.

[0006] An electric water heater enables water to be heated, instantaneously, on demand. These water heaters occupy little space and may be adapted to fit tight spaces, such as those in the smallest rooms of a dwelling. They offer speedy delivery of hot water, with a heating time that is low because of the high power of the immersion heaters used. Three-phase immersion heaters may also be used to increase the speed with which hot water is delivered.

[0007] With water heaters, there are chiefly two types of installation. Vertically installed water heaters, in which the volume of the tank extends along a vertically extending axis, and for which the connections are generally situated on a side wall of the tank are known. The tanks are conventionally in the form of a large-diameter cylinder such that the sidewall has a convex surface with a small radius of curvature allowing the attachment of the immersion heater and drillings for connections to a cold water supply and a water outlet so that it can be connected to a domestic hot water circuit of the dwelling.

[0008] For these vertically installed water heaters, the fixing of the electrical connections is generally on a generatrix of the side wall, distinct from the generatrices on which the water connections are made, these too generally being formed in this lateral wall of the tank.

[0009] The electrical connections are sensitive, given the way in which electric water heaters work. The standard EN60335-1 relating to the electrical safety of household and similar electrical appliances imposes conditions on preventing the risks involved in the use of these appliances, and notably on preventing the outbreak of fire.

[0010] The invention proposes an immersion heater comprising a resistive heating element, a flange on which the resistive heating element is mounted, two distinct terminal lugs to be connected respectively to a power source supplying electrical current to electrically power the resistive heating element, the flange being provided with a screw thread to be screwed into a complementary screw thread provided on a tank inside which the resistive heating element is intended to be placed, characterized in that the flange comprises a plate and a collar which is such that the two terminal lugs extend beyond this plate, and such that the collar stands out from this plate, the collar having a length relative to the plate that is greater than a length of the terminal lugs relative to the one same reference plane.

[0011] In particular, the reference plane is determined by an exterior surrounding periphery of the plate from which the collar stands out.

[0012] The collar of the immersion heater according to the invention acts as a shield in the event of a fire breaking out at one or both of the terminal lugs. The collar is notably effective when an immersion heater is placed on a tank of a vertical water heater, because a portion of this collar then overhangs the terminal lug which then emerges laterally from the tank. Any outbreak of fire at the terminal lug would be interrupted as the flame is being formed, because of the collar which acts as a flame arrester. The presence of this collar also makes it possible to protect any components situated in the immediate vicinity of this immersion heater, particularly an electronic circuit board positioned above the immersion heater. Specifically, electronic devices necessary for the operation of the immersion heater and, in particular, for controlling the operation thereof, such as a temperature-measuring probe, are arranged vertically above the coupling housing the immersion heater so as to avoid any damage to these devices in the event of a water leak at the immersion heater.

[0013] As a preference, the collar has an exterior periphery that is provided with at least one longitudinal edge, so that it exhibits at least two flats. In particular, this exterior periphery has an octagonal cross section so as to facilitate the use of a spanner which is helpful for increasing the lever arm needed for screwing the immersion heater into the tank. Advantageously, this octagonal periphery maintains this profile over the entire length of the collar, to make it easier still to manipulate a spanner around this flange provided with a collar, while at the same time limiting the risks of this spanner knocking against the terminal lugs and other elements arranged inside the collar.

[0014] Advantageously, the interior periphery of this collar has no roughnesses. It defines a smooth wall, for example cylindrical of circular cross section. This configuration makes it possible to avoid a buildup of heat in the wall of this collar.

[0015] As a preference, the length (11) of the terminal lug is at least less than or equal to half the length (I2) of the collar, preferably at least less than or equal to one quarter of the length of the collar, and more preferentially, at least less than or equal to one fifth of the length of the collar. Thus, the further the terminal lug is set back relative to an opening defined by the collar the greater the theoretical diameter of flame beginning at the terminal lug can be arrested by said collar.

[0016] In order to increase the flame resistance of the flange of the immersion heater, the invention defines a minimum radial distance between the terminal lug and an interior periphery of the collar, such that this distance is greater than a distance between a distal end of the terminal lug and a plane defined by the opening of the collar, or distance by which the terminal lug is set back in the collar. Specifically, as a free end of the terminal lug defines a shape of the combustion zone fed with air arriving at the collar opening, it has seemed essential to determine this dimension as a function of the distance by which this terminal lug is set back in the collar. In particular, a difference between a length of the collar and a length (11) of the terminal lug is strictly greater than 10 mm.

[0017] More particularly, the distance by which the distal end of the terminal lug is set back in the collar relative to a plane defined by an opening of the collar is strictly positive and above the minimum longitudinal distance threshold, this threshold in particular being equal to 0.5 cm.

[0018] More particularly, the terminal lugs of an immersion heater according to the invention comprise a cylindrical portion of circular cross section at the level of the plate, and are respectively extended by a flat portion extending as far as their free distal end. This configuration allows the flat portion of the terminal lugs to be oriented in such a way as to minimize the width of a combustion and fire-outbreak zone and keep the surface thereof away from the collar.

[0019] The invention also proposes a kit comprising an immersion heater according to the invention, supplied with a sealing gasket, means for attaching said immersion heater to a water heater tank, and a cover intended to conceal the immersion heater coupled to the tank, as a replacement for a used immersion heater on an operational water heater. Brief description of the drawings

[0020] The appended drawings illustrate the invention:

[0021] [Fig. 1] schematically depicts a cross-sectional view of a vertical tank provided with an immersion heater according to the invention.

[0022] [Fig. 2] schematically depicts a perspective view, in a profile from the outside, of a tank to which an immersion heater according to the invention is coupled.

[0023] [Fig. 3] depicts a schematic partial view of the immersion heater according to the invention of Figure 2.

[0024] [Fig. 4] depicts a view on a plane of section A of Figure 3.

[0025] [Fig. 5] depicts an exterior view of a tank provided with water connections and with a coupling to house an immersion heater according to the invention.

[0026] [Fig. 6] depicts an exterior view of a tank provided with an immersion heater coupled to the tank according to the invention. Description of embodiment(s)

[0027] For reasons of clarity, only the elements essential for understanding the invention have been shown schematically in these figures, which are not to scale.

[0028] The concept of the invention is described more fully below with reference to the attached drawings, which show embodiments of the concept of the invention. In the drawings, the size and the relative sizes of the elements may be exaggerated for the sake of clarity. Similar numbers refer to similar elements throughout the drawings. However, this concept of the invention can be implemented in many different forms and should not be interpreted as being limited to the embodiments set out here. Instead, these embodiments are provided so that this description is comprehensive, and communicate the scope of the concept of the invention to those skilled in the art.

[0029] Reference throughout the specification to “an / one embodiment” means that a particular function, structure or feature described in relation to one embodiment is included in at least one embodiment of the present invention. The occurrence of the expression “in an / one embodiment” in various places throughout the specification thus does not necessarily refer to the same embodiment. Furthermore, the particular functions, structures or features can be combined in any suitable manner in one or more embodiments. In addition, the term “comprising” does not rule out other elements or steps.

[0030] Figure 1 depicts a vertical water heater 1 comprising a tank 2 of cylindrical shape and provided with opposite lateral ends 3a and 3b substantially in the shape of flattened hemispherical ends. An immersion heater 5 according to the invention is depicted mounted on a cylindrical side wall 4 of the tank.

[0031] This immersion heater 5 comprises a resistive heating element 6 in the form of a loop folded over on itself and extending inside the tank perpendicular to a longitudinal axis X of the tank. This resistive heating element 6 stands out from a flange 7. The flange 7 is preferably a part obtained as a single piece as a casting.

[0032] The flange 7 is provided with a screw thread, not depicted, to engage with a complementary screw thread, not depicted, this complementary screw thread being situated directly on, or on a mounting plate attached to, the side wall 4 of the tank. In Figure 5, the side wall 4 of the tank is depicted as comprising a fluid coupling 30 emerging radially from the side wall 4, situated in the lower part of the tank, for connection to a cold water inlet, an internally threaded coupling 31 formed by tapping the thickness of the side wall and configured to engage with a screw thread provided on the external periphery of the flange 7.

[0033] In Figure 5, two fluid couplings 32 and 33 emerging radially from the side wall 4 form connections for discharging the water heated in the tank or for venting gas contained in the tank in the event of overpressure. These two fluid couplings are situated in the upper part, relative to the vertical, so that the internally threaded coupling 31 is positioned between, on the one hand, the fluid coupling 30 and, on the other hand, the two fluid couplings 32 and 33. The fluid couplings 30, 32 and 33 take the form of a barrel emerging radially out of the side wall 4, this barrel having a screw thread on its external periphery.

[0034] On the outside of the tank, and protruding laterally on the left of the side wall 4 of the tank, the flange 7 has a collar 8. This collar 8 defines an exterior wall 8b which extends perpendicular to the axis X. This exterior wall has longitudinal edges, particularly 8 edges, so that the cross section offered by this collar is octagonal and thus has 8 flats for easier collaboration with screw-tightening tools. The collar 8 defines an opening 9 which is lateral and parallel to the main axis of elongation X of the tank. In Figure 6, an electronic board 34 is fixed to the side wall 4 above the collar 8, relative to the vertical. The one same generatrix of the cylindrical tank passes both through the flange 7 and through this electronic board, the entirety of the flange 7 and the board 34 being intended to be concealed behind a vertical covering formed over the entire height of the tank.

[0035] Inside the collar 8, as visible in Figure 2, the immersion heater comprises two terminal lugs 10 and 11 standing out from a plate 12 of the flange 7. The two terminal lugs 10 and 11 are identical in shape. They each comprise a body comprising a cylindrical portion 20 extended by a flat portion 21 ultimately forming a free end 22 for each of the terminal lugs. The terminal lugs are connected through the plate 12 to two ends of the resistive heating element. The plate 12 has a recessed central zone 13 that is recessed relative to a planar annular surrounding periphery 14. The planar annular surrounding periphery 14 extends in a plane P parallel to the longitudinal axis X. The recessing of the central zone 13 is in the direction away from the side from which the collar 8 stands out from the periphery of the planar annular surrounding periphery 14.

[0036] These terminal lugs 10 and 11 are intended to be connected to an electrical power supply. When the electrical power supply is a three-phase supply, an earth connection is also provided via an additional stud 15. Fireproof earthing wiring may be provided on the additional stud 15. A second additional stud 16 may also be provided, for connecting a thermostat to the immersion heater. This additional stud 16 may alternatively allow for the attachment of a mechanical safety device.

[0037] According to a preferred embodiment of the invention, the planar annular surrounding periphery 14 comprises at least three additional studs 15, 16 and 17, these additional studs being evenly distributed about the central zone 13. In the example depicted in Figure 2, the three additional studs are positioned adjacent to a border with the central zone 13.

[0038] The presence of at least three studs evenly distributed around the central zone 13 from which the terminal lugs 10 and 11 protrude makes it possible to ensure that at least one of these additional studs will be situated below an imaginary horizontal line H passing through the two terminal lugs. Thus, the connection of the immersion heater to electronic control devices, such as a mechanical safety device or thermostat for example, will advantageously be made via the stud situated below this imaginary horizontal line H. Up to eight additional studs may be provided on the plate 12, depending on the immersion heater control requirements. These eight studs are evenly distributed, and preferably positioned near the collar so as to make the casting of the flange 7 easier to demould. These additional studs form barrels standing out from the plate 12.

[0039] A length I2 of the collar 8 between this planar annular surrounding periphery 14 and the opening 9 is determined. Because the terminal lugs 10 and 11 are set into the recessed central zone 13, for the purposes of the present description, when reference is made to the length 11 of these terminal lugs 10 and 11, this length is measured only between the free end of each terminal lug and the plane P. For the sake of the legibility of Figure 3, the additional studs such as 15, 16 and 17 are not depicted in this partial perspective view. As a preference, this length 11 of the terminal lugs is formed exclusively by the flat portion of these terminal lugs. The recessing of the central zone 13 relative to the plane P is such that the length 11 of the terminal lugs represents between 20% and 80% of the 5 total length It of the terminal lugs, this total length It corresponding to the length of terminal lug protruding from the recessed central zone.

[0040] The free ends of the terminal lugs are set back from the opening by a setback distance d. As a preference, the set-back distance d is greater than the length 11 of these terminal lugs Wand 11 relative to the planar annular io surrounding periphery 14. The length I2 of the collar is greater than this set-back distance d between a free end of the terminal lugs and a plane defining the opening 9 of the collar.

[0041] As is depicted in Figure 4, a radial distance E is defined between a terminal lug and the closest interior border of the collar.

Claims

1. Immersion heater (5) comprising a resistive heating element (6), a flange (7) on which the resistive heating element is mounted, two distinct terminal lugs (10, 11) to be connected respectively to a power source supplying electrical current to electrically power the resistive heating element, the flange being provided with a fixing means so that it can be mounted on a tank inside which the resistive heating element is intended to be placed, characterized in that the flange comprises a plate (12) and a collar (8) which is such that the two terminal lugs extend beyond this plate, and such that the collar stands out from this plate, the collar having a length (I2) relative to a reference plane (P) of the plate that is greater than a length (11) of the terminal lugs relative to this same reference plane.

2. Immersion heater according to Claim 1, characterized in that the length (11) of the terminal lug is at least less than or equal to half the length (I2) of the collar.

3. Immersion heater according to one of Claims 1 or 2, characterized in that a difference (d) between the length (I2) of the collar and the length (11) of the terminal lug is strictly greater than 10 mm.

4. Immersion heater according to any one of the preceding claims, characterized in that the plate (12) has a recessed central zone (13) that is recessed relative to a planar annular surrounding periphery (14), this planar annular surrounding periphery (14) defining the reference plane (P).

5. Immersion heater according to any one of the preceding claims, wherein a minimum radial distance (E) between the terminal lug and an interior periphery of the collar is greater than a distance (d) between a distal end of the terminal lug and a plane defined by an opening of the collar.

6. Immersion heater according to the preceding claim, wherein the distance (d) between a distal end of the terminal lug and a plane (9) defined by an opening of the collar is strictly positive and above a minimum longitudinal distance threshold, this threshold in particular being equal to 0.5 cm.

7. Immersion heater according to any one of the preceding claims, wherein the terminal lugs comprise a cylindrical portion (20) of circular crosssection at the level of the plate, and are respectively extended by a flat portion (21) extending as far as their free distal end (22).

8. Immersion heater according to any one of the preceding claims, characterized in that the collar has an external periphery (8a) provided with at 5 least one longitudinal edge so that it exhibits at least two flats.

9. Kit comprising an immersion heater according to any one of the preceding claims and a sealing gasket, means for attaching said immersion heater to a water heater tank and a cover intended to conceal the immersion heater coupled to the tank.io11

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