FR2777410A1 - THERMOPLONGER FORMING DEVICE THAT CAN BE USED IN PARTICULAR IN A WATER CIRCULATION HEATER - Google Patents

Abstract

The immersion heater has a heating cartridge (3), formed with a sleeve (4) housing and an electric resistance element (5) fixed inside an external collector (1) that contains a heat transfer fluid (2). This fluid has good electrical insulation properties, and is usually a mineral oil.

Description

The present invention relates to a device forming an immersion heater

can be used in particular

  in a water circulation heating radiator.

  There is known a device forming an immersion heater comprising a collector closed in a sealed manner at its two ends and containing a heat transfer liquid to be heated and, housed in the collector while immersed in the heat transfer liquid, a heating cartridge with electric heating resistance embedded in the cartridge being electrically isolated from it. More specifically, the heating cartridge comprises a cylindrical metallic tubular body, for example of steel, in which is compacted magnesia insulating the

  electrical resistance of the cartridge tube.

  However, this known device has the major drawback of not ensuring perfect safety from the point of view of electrical insulation since the internal electrical resistance of the heating cartridge may accidentally come into contact with the internal wall of the metal tube of the cartridge, for example at because of a crumbling of the magnesia due to a defect in the compaction thereof or a crack in the cartridge tube through which the heat transfer fluid can penetrate to disintegrate the compacted magnesia, so that the short-circuit current circuit reaching the metal collector can cause electric shocks to the user when the device is integrated in a

  metal heating radiator with water circulation.

  To improve the degree of safety of such an immersion heater device, it has been proposed to produce the heating cartridge in two concentric cylindrical metal tubes, electrically isolated from each other by compacted magnesia, the internal tube comprising the electrical resistance. heater embedded in compacted magnesia to isolate it from the inner tube. However, if this double-insulated heating cartridge provides the desired degree of security, it is very expensive to produce since it requires not only the two internal and external concentric tubes, but also to compact magnesia in the internal tube to drown the electrical resistance and between the two inner and outer tubes to isolate them

one of the other.

  The object of the present invention is to eliminate the drawbacks of the above known devices by proposing a device forming an immersion heater comprising a collector in the form of a tube closed in leaktight manner at its two ends and containing a heat transfer liquid to be heated and housed in the collector by bathing in the heat transfer liquid, a heating cartridge with internal electrical heating resistance embedded inside the cartridge being electrically insulated therefrom and which is characterized in that

  that the heat transfer liquid is electrically insulating.

  The heat transfer liquid is mineral oil, preferably of the paraffinic type with a high viscosity index. The heating cartridge is fixed in the collector substantially coaxially thereto by being carried at one of its ends by a support sleeve made of electrically insulating material fixed to

  through one of the end walls of the manifold.

  Advantageously, the cartridge support sleeve comprises an externally threaded cylindrical part engaging in a corresponding tapped hole in the end wall of the manifold and a flange bearing on the external face of the end wall in the position of sleeve blocking in

the end wall.

  Preferably, the heating cartridge is fixed

  to the support sleeve by welding or gluing.

  The heating cartridge comprises a cylindrical tube containing compacted magnesia in which the electric heating resistor is embedded, the two ends of which are connected respectively to two supply conductor wires passing through the support sleeve projecting outside the latter. . The heating cartridge comprises one or more rings of electrically insulating material fitted to

force on the cartridge tube.

  The free end of the cartridge is covered

  a cap of electrically insulating material.

  The tube of the heating cartridge and the

  manifold are metallic, for example steel.

  According to a variant, the tube of the heating cartridge is made of an electrically insulating material,

for example ceramic.

  The invention will be better understood and other aims, characteristics, details and advantages thereof

  will appear more clearly during the description

  Explanatory which will follow made with reference to the appended schematic drawings given solely by way of example illustrating an embodiment of the invention and in which: - Figure 1 is a view in longitudinal section of the device forming an immersion heater of the invention; and - Figure 2 is a sectional view along the

line II-II of figure 1.

  The device forming an immersion heater will be described in the application to a water circulation heating radiator in which it is integrated to heat the circulating water, but it is understood that it can be used for other different applications

  requiring the heating of a liquid or a fluid.

  Referring to Figures 1 and 2, the immersion heater device comprises a collector 1 in the form of a metallic cylindrical tube closed in leaktight manner at its two ends and containing a heat transfer liquid

to heat 2.

  The device further comprises, housed in the collector 1 while immersed in the heat transfer liquid 2, a heating cartridge 3 making it possible to heat the heat transfer liquid 2 and constituted by a metallic cylindrical tube 4 in which there is an internal electrical heating resistance 5 embedded in magnesia M compacted in the tube 4 in order to electrically isolate the resistor 5 from the tube 4. The resistor consists of a conductive wire wound in a spiral with contiguous turns and has substantially the shape of an elongated U so that these two free ends leaving the tube 4 are connected respectively to two wires

  external power conductors 6.

  According to the invention, the heat transfer liquid 2 is electrically insulating and is preferably constituted by mineral oil, preferably of the paraffinic type with a high viscosity index. For example, the mineral oil is that of the company SHELL marketed under the name "SHELLFLEX"

type 110 FC.

  The heating cartridge 3 is fixed in the collector 1 substantially coaxially thereto by having one of its free floating ends and its opposite end secured to a support sleeve 7 made of an electrically insulating material fixed to

  through one of the end walls of the manifold 1.

  As shown in FIG. 1, the support sleeve 7 comprises a cylindrical part 7a externally threaded to engage in a corresponding tapped hole 1b passing through the end wall 1a of the manifold 1 and a flange part 7b coming to bear on the face external of the end wall la when the support sleeve 7 is locked by screwing into the wall la. The support sleeve 7 further comprises a cylindrical end 7c in which is joined, by welding or gluing, the corresponding end of the heating cartridge 3. The supply wires 6 connected to the two ends of the heating resistor 5 pass through a internal drilling of the support sleeve 7 to project outside the

collector 1.

  The heating cartridge 3 comprises one or more rings 8, in this case two in number, made of an electrically insulating material and fixed to the tube 4 of the cartridge 3 by being force-fitted thereon at a distant distance l one of the other. If necessary, the free end of the heating cartridge 3 can be covered with a cap (not shown) made of electrically insulating material. The rings 8 and this cap prevent accidental electrical contact between the tube 4 and the manifold 1. Of course, the rings 8 and the cap are made of a material which also makes it possible to withstand the operating temperatures of the

heating cartridge 3.

  The invention described above thus makes it possible to produce an immersion heater constituted by a heating cartridge known per se as described at the beginning of the

  description and with characteristics

  of extremely high electrical insulation ensuring, thanks to the insulating heat transfer liquid, a very high degree of user safety, especially when the immersion heater is used in a radiator

water circulation heating.

  Various modifications can be made to the immersion heater device without departing from the scope of the present invention. Thus, the support sleeve 7, instead of being made of an electrically insulating material, can be made of metallic material coated with insulating material. In addition, the tube 4 of the heating cartridge 3, instead of being metallic, can be made of electrically insulating material, such as by

example of ceramic.

Claims (11)

  1. Device forming an immersion heater comprising a collector (1) in the form of a tube closed in leaktight manner at its two ends and containing a heat transfer liquid to be heated (2) and, housed in the collector (1) while immersed in the heat transfer liquid (2 ), a heating cartridge (3) with internal electric heating resistance (5) embedded in the cartridge (3) being electrically isolated from the latter, characterized in that   the heat transfer liquid (2) is electrically insulating.   2. Device according to claim 1, characterized in that the heat transfer liquid (2) is mineral oil, preferably of the paraffinic type to high viscosity index.   3. Device according to claim 1 or 2, characterized in that the heating cartridge (3) is fixed in the collector (1) substantially coaxial therewith by being carried at one of its ends by a support sleeve ( 7) of electrically insulating material fixed through one (the) of the end walls of the manifold (1).   4. Device according to claim 3, characterized in that the support sleeve (7) of the cartridge (3) comprises an externally threaded cylindrical part (7a) engaging in a corresponding threaded hole (lb) of the wall end (la) of the manifold (1) and a flange (7b) coming to bear on the external face of the end wall (la) in the locking position of the sleeve (7) in the wall end (la).   5. Device according to claim 3 or 4, characterized in that the heating cartridge (3) is fixed to the support sleeve (7) by welding or by bonding.   6. Device according to one of claims 3 to   , characterized in that the heating cartridge (3) comprises a cylindrical tube (4) containing compacted magnesia in which the electric heating resistor (5) is embedded, the two ends of which are connected respectively to two supply conductor wires (6 ) passing through the support sleeve (7)   protruding outside of it.   7. Device according to claim 6, characterized in that the heating cartridge (3) comprises one or more rings (8) of electrically insulating material force fitted on the tube (4) of the cartridge (3).   8. Device according to claim 6 or 7, characterized in that the free end of the heating cartridge (3) is covered with a cap made of material electrically insulating.   9. Device according to one of claims 6 to   8, characterized in that the tube (4) of the heating cartridge (3) and the manifold (1) are metallic, for example steel.   10. Device according to one of claims 6 to   8, characterized in that the tube (4) of the heating cartridge (3) is made of a material electrically insulator, for example ceramic.   11. Use of the immersion heater device such   as defined in claims 1 to 10 in a radiator water circulation heating.