Immersion heater with fire protection flange

Abstract

Immersion heater (5) comprising a heating resistor (6), a flange (7) on which the heating resistor is mounted, two separate lugs (10, 11) to be respectively connected to a source of electrical power to electrically supply the heating resistor, the flange being provided with a thread to be screwed to a complementary thread provided on a tank of a domestic water heater, the flange comprising a plate (12) and a collar (8) such that the two lugs protrude from this plate, and such that the collar is erected on the plate, the collar having a length (l2) relative to the plate greater than a distance (d) between a free end of the lugs and a plane defining the opening of the collar. Figure for the abstract: Fig. 3

Description

Title of the invention: Immersion heater with fire protection flange

[0001] The present invention relates to the field of water heater installations. In particular, the invention relates to a connector for connecting an immersion heater, also called 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 seal, means for fixing said immersion heater to a tank of a water heater, and a cover intended to mask the immersion heater connected to the tank.

[0003] To ensure the supply of 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 retained in a threaded terminal block and screwed to a plate itself bolted to a wall of the tank.

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

[0005] An electric water heater allows water to be heated on demand, and instantly. These water heaters are compact and can be adapted to restricted environments, such as the smallest rooms in a home. They offer rapid delivery of hot water, with a reduced heating time due to the high power of the immersion heaters used. Three-phase immersion heaters can also be used to increase the speed of hot water delivery.

[0006] Among water heaters, there are mainly two types of installation. We know vertically installed water heaters, for which the volume of the tank extends along a vertical axis of elongation, and for which the connection is generally located at the level of a side wall of the tank. The tanks are conventionally cylindrical in shape with a large diameter, so that the side wall has a convex surface with a small radius of curvature allowing the fixing of the immersion heater and holes for connections to a cold water supply and a water drain for connection to a domestic hot water circuit of the dwelling.

[0007] For vertically installed water heaters, the fixing of the electrical connection is generally located on a generator of the side wall, separate from the generators on which the hydraulic connections are located, generally also formed in this side wall of the tank.

[0008] Electrical connections are sensitive given the way electric water heaters operate. The EN60335-1 standard relating to the electrical safety of household and similar electrical appliances imposes conditions for preventing risks in the use of these appliances, and in particular the prevention of fires.

[0009] The invention proposes an immersion heater comprising a heating resistor, a flange on which the heating resistor is mounted, two separate terminals to be respectively connected to a source of electrical current to electrically supply the heating resistor, the flange being provided with a thread to be screwed to a complementary thread provided on a tank inside which the heating resistor is intended to be placed, characterized in that the flange comprises a plate and a collar such that the two terminals protrude from this plate, and such that the collar is erected on the plate, the collar having a length relative to the plate greater than a length of the terminals relative to the same reference plane.

[0010] In particular, the reference plane is determined by an external peripheral circumference of the plate on which the collar is erected.

[0011] The collar of the immersion heater according to the invention forms a screen in the event of a fire starting at one or more terminals. The collar is particularly effective when an immersion heater is placed on a tank of a vertical water heater, because the terminal emerging laterally from the tank is then overhung by a portion of this collar. Any fire starting at the terminal would be interrupted in the formation of its flame due to the collar forming a fire barrier. The presence of this collar also makes it possible to protect any part located in the immediate environment of this immersion heater, and in particular an electronic circuit board arranged above the immersion heater.In fact, electronic devices necessary for the operation of the immersion heater and in particular for monitoring its operation, such as a temperature measuring probe, are arranged vertically above the connection receiving the immersion heater in order to avoid any damage to these devices in the event of a water leak at the immersion heater.

[0012] Preferably, the collar has an outer circumference provided with at least one longitudinal edge, so as to have at least two flats. In particular, this outer circumference has an octagonal section in order to facilitate the use of a useful key to increase the lever arm necessary for fixing the immersion heater to the tank by screwing. Advantageously, this octagonal circumference extends over the entire length of the collar, in order to further facilitate the handling of a key around this flange provided with a collar, while limiting the risks of impact between this key and the terminals and other elements arranged in the collar.

[0013] Advantageously, the inner periphery of this collar is free from roughness. It defines a smooth wall, for example cylindrical with a circular section. This configuration makes it possible to avoid an accumulation of heat in the wall of this collar.

[0014] Preferably the length (11) of the lug is at least less than or equal to half the length (12) of the collar, preferably at least less than or equal to a quarter of the length of the collar, and more preferably at least less than or equal to a fifth of the length of the collar. Thus the further the lug is set back relative to an opening defined by the collar, the more a theoretical flame diameter starting at the lug would be prevented by said collar.

[0015] To increase the fire resistance of the flange of the immersion heater, a minimum radial distance is defined in the invention between the lug and an inner periphery of the collar, such that this distance is greater than a distance between a distal end of the lug and a plane defined by the opening of the collar, or withdrawal distance of the lug in the collar. Indeed, a free end of the lug defining a combustion zone shape supplied by the air arriving at the opening of the collar, it appeared essential to determine this dimension as a function of the withdrawal distance of this lug in the collar. In particular, a difference between a length of the collar and a length (11) of the lug is strictly greater than 10 mm.

[0016] More particularly, the withdrawal distance of the distal end of the lug in the collar relative to a plane defined by an opening of the collar is strictly positive and greater than a minimum longitudinal distance threshold, in particular this threshold is equal to 0.5 cm.

[0017] More particularly, the terminals of an immersion heater according to the invention comprise a cylindrical portion of circular section at the right of the plate, and are extended respectively by a flat portion up to their free distal end. This configuration makes it possible to orient the flat portion of the terminals in order to minimize the width of a combustion and fire starting zone, and to move its surface away from the collar.

[0018] The invention also provides a kit comprising an immersion heater according to the invention, provided with a seal, means for fixing said immersion heater to a tank of a water heater, and a cover intended to mask the immersion heater connected to the tank, for replacing a used immersion heater on an operational water heater. Brief description of the drawings

[0019] The attached drawings illustrate the invention:

[0020] [Fig. 1] schematically represents a sectional view of a vertical tank provided with an immersion heater according to the invention.

[0021] [Fig.2] schematically represents a perspective profile view from the outside of a tank to which an immersion heater according to the invention is connected.

[0022] [Fig.3] represents a partial schematic view of the immersion heater according to the invention of [Fig.2].

[0023] [Fig.4] represents a view along section plane A of [Fig.3].

[0024] . [Fig.5] represents an external view of a tank provided with connections hydraulics and a connection to receive an immersion heater according to the invention.

[0025] [Fig.6] represents an external view of a tank provided with an immersion heater connected to the tank according to the invention. Description of embodiment(s)

[0026] For reasons of clarity, only the elements essential for understanding the invention have been shown schematically in these figures, and this without respecting the scale.

[0027] The inventive concept is described more fully below with reference to the accompanying drawings, in which embodiments of the inventive concept are shown. In the drawings, the size and relative sizes of elements may be exaggerated for clarity. Like numerals refer to like elements throughout the drawings. However, this inventive concept may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Instead, these embodiments are provided so that this description is complete, and communicates the scope of the inventive concept to those skilled in the art.

[0028] A reference throughout the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the occurrence of the phrase "in an embodiment" at various locations throughout the specification does not necessarily refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Furthermore, the term "comprising" does not exclude other elements or steps.

[0029] [Fig.l] represents a vertical water heater 1 comprising a tank 2 of cylindrical shape and provided with opposite lateral ends 3a and 3b which are substantially hemispherical and flattened. An immersion heater 5 according to the invention is shown mounted on a cylindrical lateral wall 4 of the tank.

[0030] This immersion heater 5 comprises a heating resistor 6 in the form of a loop folded back on itself, and extending inside the tank, along a longitudinal axis X of the tank. This heating resistor 6 is mounted on a flange 7. The flange 7 is preferably a part obtained in one piece by foundry molding.

[0031] The flange 7 is provided with a thread, not shown, to cooperate with a complementary thread not shown, this complementary thread being located on an attached plate, or directly on the side wall 4 of the tank. [Fig.5], the side wall 4 of the tank is shown comprising a hydraulic connection 30 radially emerging from the side wall 4, located in the lower part of the tank, for connection to a cold water inlet, an internal threaded connection 31 formed by tapping in the thickness of the side wall, and configured to cooperate with a thread provided on the outer periphery of the flange 7.

[0032] Figures 5, two hydraulic connections 32 and 33 radially emerging from the side wall 4 form connections for the evacuation of the heated water in the tank, or of the gas contained in the tank in the event of overpressure. These two hydraulic connections are located in the upper part, relatively vertical, so that the internal threaded connection 31 is arranged between on the one hand the hydraulic connection 30 and the two hydraulic connections 32 and 33. The hydraulic connections 30, 32 and 33 are in the form of a barrel emerging radially externally from the side wall 4, this barrel being provided with a thread on its external periphery.

[0033] Outside the tank, and projecting laterally to the left of the side wall 4 of the tank, the flange 7 has a collar 8. This collar 8 defines an outer wall 8b which extends perpendicular to the axis X. This outer wall has longitudinal edges, in particular 8 edges, so that the section proposed by this collar is octagonal and thus has 8 flats to facilitate cooperation with screwing tools. The collar 8 defines an opening 9 which is lateral and parallel to the main elongation axis X of the tank. [Fig.6], above the collar 8, relatively vertical, an electronic card 34 is fixed to the side wall 4. The same generatrix of the cylindrical tank passes both through the flange 7 and this electronic card, together the flange 7 and the card 34 being intended to be hidden behind a vertical sheath formed over the entire height of the tank.

[0034] Inside the collar 8, as seen in [Fig.2], the immersion heater comprises two terminals 10 and 11 erected from a plate 12 of the flange 7. The two terminals 10 and 11 are identical in their shape. They each comprise a body comprising a cylindrical portion 20 extended by a flat portion 21 to form a free end 22 for each of the terminals. The terminals are connected through the plate 12 at two ends of the heating resistor. The plate 12 has a sunken central zone 13 relative to a planar annular peripheral periphery 14. The planar annular peripheral periphery 14 extends in a plane P parallel to the longitudinal axis X. The depression of the central zone 13 is opposite the side from which the collar 8 stands at the periphery of the planar annular peripheral periphery 14.

[0035] These terminals 10 and 11 are intended to be connected to a power supply. When the power supply is three-phase, an earth connection is also provided via an additional pad 15. Flame-retardant wiring to earth may be provided on the additional pad 15. A second additional pad 16 may also be provided for connecting a thermostat to the immersion heater. This additional pad 16 may alternatively allow the attachment of a mechanical safety device.

[0036] According to a preferred embodiment of the invention, the planar annular peripheral periphery 14 comprises at least three additional pads 15, 16 and 17, these additional pads being equally distributed around the central zone 13. In the example shown [Fig.2], the three additional pads are arranged adjacent to a border with the central zone 13.

[0037] The presence of at least three equally distributed pads around the central zone 13 from which the lugs 10 and 11 protrude makes it possible to guarantee that there is at least one of these additional pads which is located below an imaginary horizontal line H passing through the two lugs. Thus, the connection of the immersion heater with electronic control devices, such as a mechanical safety device or a thermostat for example, will advantageously be made via the pad located below this imaginary horizontal line H. Depending on the control needs of the immersion heater, up to eight additional pads can be provided on the plate 12. These eight pads are equally distributed, and preferably arranged near the collar in order to facilitate the demolding of the flange 7. These additional pads form barrels erected on the plate 12.

[0038] A length 12 of the collar 12 is determined between this flat annular peripheral periphery 14 and the opening 9. The lugs 10 and 11 being inserted into the sunken central zone 13, for the purposes of the present description, when reference is made to the length 11 of these lugs 10 and 11, this is measured only between the free end of each lug and the plane P. For the readability of [Fig. 3], the additional studs such as 15, 16 and 17 are not shown in this partial perspective view. Preferably, this length 11 of the lugs is exclusively formed by the flat portion of these lugs. The depression of the central zone 13 relative to the plane P is such that the length 11 of the lugs represents between 20% and 80% of the total length It of the lugs, this total length It corresponding to the length of lug protruding from the central pressed-in zone.

[0039] The free ends of the lugs are set back by a setback distance d relative to the opening. Preferably, the setback distance d is greater than the length 11 of these lugs 10 and 11 relative to the flat annular peripheral periphery 14. The length 12 of the collar is greater than this setback distance d between a free end of the lugs and a plane defining the opening 9 of the collar.

[0040] As shown in [Fig.4], a radial distance E is defined between a lug and the inner edge closest to the collar.

Claims

Claims

1. Immersion heater (5) comprising a heating resistor (6), a flange (7) on which the heating resistor is mounted, two separate lugs (10, 11) to be respectively connected to a source of electrical current to electrically supply the heating resistor, the flange being provided with a fixing means to be mounted on a tank inside which the heating resistor is intended to be placed, characterized in that the flange comprises a plate (12) and a collar (8) such that the two lugs protrude from this plate, and such that the collar is erected on the plate, the collar having a length (12) relative to a reference plane (P) of the plate greater than a length (11) of the lugs relative to this same reference plane, and in that the length (11) of the lug is at least less than or equal to half the length (12) of the collar.

2. Immersion heater according to claim 1, characterized in that a difference (d) between the length (12) of the collar and the length (11) of the terminal is strictly greater than 10 mm.

3. Immersion heater according to any one of the preceding claims, characterized in that the plate (12) comprises a sunken central zone (13) relative to a flat annular peripheral periphery (14), this flat annular peripheral periphery 14 defining the reference plane (P).

4. An immersion heater according to any preceding claim, wherein a minimum radial distance (E) between the terminal and an inner periphery of the collar is greater than a distance (d) between a distal end of the terminal and a plane defined by an opening in the collar.

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

6. Immersion heater according to any one of the preceding claims, in which the terminals comprise a cylindrical portion (20) of circular section at right angles to the plate, and extend respectively by a flat portion (21) to their free distal end (22).

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

8. Kit comprising an immersion heater according to any one of the preceding claims and a seal, means for fixing said immersion heater to a tank of a water heater, and a cover intended to mask the immersion heater connected to the tank.

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