FR2749645A1 - REGULAR SELF-PROPELLED HEATER - Google Patents

Abstract

The present invention relates to a heater for an oil burner comprising: - a tubular heating body (4) traversed longitudinally by at least one duct (5), - at least one heating element of the wafer type (8, 9) with a positive coefficient of temperature (PTC), - a supply circuit (26) of the PTC (s), - a temperature detection circuit (15), controlling the start-up of the burner, characterized in that at least one PTC plate (8, 9) is maintained in support (F) on at least one flat face (4a, 4b) of the heating body (4) by a wing (10, 11) coming from the area of intersection between said flat face of the body (4a , 4b) and the immediately adjacent face (4d), said wing (10, 11) having an adequate thickness to be able to be suitably folded against the opposite external face of said CTP plate (8, 9) and thus recover the calories diffusing to the outside of it.

Description

2749645,

REGULAR SELF-PROPELLED HEATER

  The invention relates to an improvement made to the devices intended to heat the fuel oil before its

  spraying in an oil burner.

  In the field of oil burners, it is quite known to reheat the oil before its admission to the nozzle to be sprayed. This reheating is necessary to reduce the viscosity of fuel oil on the one hand, and to increase the fineness of

spraying on the other hand.

  Many solutions already exist, consisting essentially of heating a heating body

  interposed between the oil pump and the nozzle.

  Generally it is known to have around this heating body, with high thermo-conductive characteristics, a more or less conventional heating device which will of course seek to regulate the operation; indeed, while it is essential to heat the oil prior to spraying, as we have seen, it is also important not to exceed a maximum reheat temperature from which the coking phenomena would begin to appear, and knows the particularly harmful effects on

level of sprinklers.

  It has therefore long been thought of heating systems coupled with temperature control devices which, in addition to their often very high cost, hardly accommodate the lack of accessibility offered by the vast majority of oil burners in boilers. The oil heaters must indeed be as close as possible to the sprinklers, that is to say in often very congested areas, thus leaving little room for developing thermal regulations. Given these often severe congestion requirements, many manufacturers have already suggested in the past, to use self-regulating systems in the -2-

  heating oil burners.

  Of all the systems proposed, the use of positive temperature coefficient heating elements (PTC thermistor) provides a relatively decisive solution.

  By way of example, it is possible to read in the DE patent

  12 000 filed on 27 March 1979 by MEKU METALL

  description of a device for reheating the

  fuel oil upstream of the nozzle of a burner whose heating system was made from thermistors with a positive temperature coefficient held around a heating body inside which circulates the oil to be heated by a coating of the assembly mounted in a

insulating resin.

  The operation of such a device is simple: the energization of the heating elements provides the primary effect sought namely the temperature increase of the heating body but also of the thermistors, thus causing the elevation of the internal resistance which then comes to limit the electrical power absorbed and therefore reduce the production of calories. It is therefore understood that such an assembly provides a thermal self-regulation since the theoretical increase in temperature is automatically limited by the thermal power of the heating element which

  decreases as the temperature increases.

  Such a self-regulating device has the advantage of a very small footprint and especially a high level of use; however, such a device is particularly difficult to regulate because its effectiveness is closely related to mechanical problems often random contact between the heating elements and heat transfer means. It is well understood that if such contact was not particularly careful, it could lead to a rapid rise in temperature of the thermistor, resulting in a low heat transfer to the product to be heated, with the consequence that the internal resistance of the The thermistor, increasing proportionally, would immediately limit the heating power, which would further amplify the heat transfer defect; Conversely, a particularly careful contact between the thermistors and the heating body allows the latter to recover a maximum of calories, that is to say, to limit the temperature rise of the thermistor which can thus provide a power sufficient and constant to heat the fuel oil. In addition, such heaters must necessarily fit in a small footprint as has already been said, it is mandatory that these devices are particularly effective, since the thermal exchange surfaces available are necessarily

low.

  In this regard, it has already been suggested in the German application DE-42 16 008 of 15 May 1992 on behalf of RAPA RAUSCH to replace the coating techniques to keep the thermistors around the heating body, as described in the patent MEKU already mentioned, by two lateral flanges coming by means of upper and lower clips to encircle the thermistors around the heating body. If it undeniably results in an improvement of the thermal contact between heating elements and heating body, it remains that such a solution only very incidentally takes into account heat losses corresponding to the external faces of the thermistors, which leads to the elevation of their temperature and therefore to the diminution of their power; in addition, it can be observed that the mechanical fasteners by clips necessarily have reliefs which must nevertheless be inserted in a space often restricted; in this sense, and because of the current standardization of oil burners, the envelopes for receiving the heaters, have inner and outer dimensions set by the burner manufacturers; the most common models of heater envelopes have an outer diameter of 18.4 mm for a working length of 92 mm; it is understandable then that one seeks for this material an optimal surface of exchange, since in any case its external dimensions are fixed. It is therefore essential to use the maximum of the interior volume of the envelope, while respecting the conditions developed previously, namely: - to make as intimate contact as possible between the heating elements of the CTP type and the heating body, - arrange the heating elements so that the heat losses are as low as possible in order to ensure optimal power transfer to the heating element, and thus to the fuel oil that we want

warm up before spraying.

  For this purpose, it is proposed according to the invention, an oil burner heater, comprising inside a cylindrical shell called heater holder: - a tubular heating body of highly thermo-conductive material, section preferably transverse transverse, longitudinally traversed by at least one duct of circular section having means for the sealing coupling, on one side to a pressurized inlet of the oil to be heated and the other to the nozzle holder of the burner, - at least a platelet heater of the positive temperature coefficient (PTC) type fitting against at least one planar face of the tubular heater, and preferably two faces

opposite planes.

  a supply circuit for the one or more PTCs; a temperature detection circuit controlling the start-up of the burner, characterized in that at least one PTC board is held in abutment on at least one plane face of the heating body by an advantageously rectangular wing made of a highly thermo-conductive material, of a width substantially equal to that of the body and issuing from the zone -5 of intersection between said planar face of the body and the immediately adjacent face, said wing extending over practically all the length of the heating body and having an adequate thickness to be able to be folded properly in cooperation with suitable folding zones, against the opposite side of said CTP plate and thus recover the calories diffusing to

outside of it.

  According to the solution of the invention, such a heater has the advantage of recovering the unavoidable thermal losses on the external faces of the CTP platelets by pumping and thermo-injection in the heating body, thus contributing to a very good improvement.

  net of the thermal efficiency of the whole.

  Another object of the invention which contributes to reinforcing the mechanical contact between the various elements involved in heating, is to provide the heater with provisions characterized in that the folding zones of each wing consist of a double preforming of their base from of their connecting line with the heating body, such as when mounting by lateral pressure on a wing, the latter, articulated first around its connecting line, then around a second line parallel to said line connection to escape the thickness of the plate CTP-, comes in parallel position to the contact face of the heating body while remaining in positive support on the entire outer surface of

the CTP wafer.

  According to this first general variant of the invention, it is clear that it is possible both to obtain an intimate contact of the heating body and the wing resulting therefrom, with the two active faces of the

CTP chips.

  According to a preferred variant of the invention, the heating body may be differently equipped to achieve the same final result and, in this sense, it is characterized in that a reserve of several folds is provided at the base of each wing. extends from its line 6-connection, first outwardly and substantially in the plane of the contact face of the heating body with the plates, then performs a complete reversal substantially following a semicircle of diameter approximately equal to the thickness of the CTP plate to bring by lateral pressure the contact surface of the wing against said plate to hold it against the heating body so that the wing remains well parallel to the contact face of the body and is, in addition, positive support on the entire external surface of the same

CTP wafer.

  Other features and benefits will emerge

  better still of the description which will be given below

  a preferred example, although not limiting, of the oil burner heater according to the invention with reference to the accompanying drawings in which: - Figure 1 shows a longitudinal and elevational sectional view of the heater showing the assembled assembly; - Figure 2 shows in left view the

  heater of Figure 1 according to the sectional plane II-

  II - Figure 3 is a top view of the heater showing in a partial cutaway in section the counterblock wedge of the body within its casing in its preferred form of wave spring blade; FIG. 4 is a perspective view of the single heating body provided with its two lateral wings, one on the left in the operating position, the other on the right in an inclined position before mounting the CTP plates by folding along the arrow F ; - Figure 5 is a perspective view showing by successive tearing and just before their insertion between the wings and the heating body of Figure 4, all the intermediate elements comprising the side heating elements, the plastic block and the flexible circuit d supply of CTP boards, including electrodes and thermostat connection -7-

regulation.

  With reference to FIGS. 1 to 3, the heater, according to its preferred embodiment, internally comprises a cylindrical casing 1 normally made of steel, having a diameter of 18.4 mm in its useful part and a total length of about 92 mm; these dimensions correspond to the dimensions widely used in other heaters; at one end of the casing 1 is fitted a connection assembly 2 to the burner pump and the other, a device 3 for connecting the heater to the burner spray nozzle (such connectors are shown in FIG. in fine mixed lines

in Figures 1 and 3).

  Inside the casing 1, there is the heating body 4 whose tubular shape of square cross-section determines four rectangular outer faces, namely: two right and left lateral faces 4a, 4b, an upper face 4c and one face lower 4d; the tubular heating body 4 is made of a highly thermo-conductive material such as brass, copper or bronze and according to the most advantageous version of the invention, it is provided in the axis of the heating body 4, a longitudinal duct 5 opening, of circular section, inside which the heating oil can freely circulate to be heated, or better, flow through stuffing elements 6 such as, for example, sintered bronze balls or similar, thus increasing the heat exchange surfaces between the heating body 4 and the

oil.

  As an accessory to the assembly, the inner pipe 5 of the heating body 4 having, at each of its two ends, an O-ring 7 is mounted in a circular counterbore intended to receive, in a sealed manner, the connectors 2, 3 of the pipes coming respectively from

pump and nozzle.

  Supported by one of their active faces, on the lateral faces 4a and 4b of the heating body 4, heating elements 8, 9 are arranged over the entire length of said body 4, over a height substantially identical to the width of the side faces 4a, 4b of the same body, to provide an exchange area as large as possible between said heating elements 8,9 and the

heating body 4.

  According to an important characteristic of the invention, the heating elements 8, 9 are ceramic plates with a positive temperature coefficient (PTC); it is recalled here that such ceramics subjected to an electric current between their two active faces heat up and their internal resistance, unlike the conventional material increases with temperature; at constant voltage, it follows that the current decreases and therefore, the power absorbed decreases: it results self-limitation in temperature of these heating elements and therefore, a self-limitation of the

production of heat energy.

  It will be understood, therefore, that the power of such heating elements 8,9 must be accurately calculated, and on the basis of this calculation which is known to those skilled in the art, an optimum thickness of the plates 8,9 will emerge; Of course, it is also necessary to take into account the phenomenon of self-limitation characteristic of CTP ceramics and therefore, to treat particularly all

thermal contact surfaces.

  In addition to positioning them as close as possible to the lateral faces 4a and 4b of the body 4 by mechanical means incorporating the power supply circuit of the CTPs which will be detailed later, it is expected to recover the calories that can escape on the external faces of the two platelets CTP 8,9. Indeed, if we naturally allowed to radiate the calories emitted by the external faces of CTP 8,9 and given the very poor coefficient of heat conduction of the air, we would contribute to a very high temperature rise of ceramics 8,9, so that these would be very quickly limited in power - 9 - and it would become difficult to obtain a power

acceptable thermal.

  In the context of the invention and according to its main characteristic, the external face of the CTP 8.9 is coupled with side wings 10, 11 arranged, as will be said later, to bear positively on the entire external surface of each CTP. , in order to pump the calories from these same external faces and bring them back to the heating body 4 where they can be thermally

reinjected.

  Finally, the heating body assembly 4, plates 8, 9,11 pumping wings and supply circuit are slid into the casing 1 of the heater and counterblocked between its inner wall and each side wing 10,11 by means of two springs 12,13 mounted longitudinally forcibly, at the same time

other rooms.

  Advantageously, the two springs 12, 13 consist of preferably spring steel blades, corrugated according to their edge, providing an elastic effect well distributed over the entire length of the wings, 11, thanks to the summits of the corrugation which alternate in support on the wings 10,11, then on the inner face of the casing 1; it is clear that such a setting, in addition to centering the assembly mounted in the cylindrical casing 1 and block it in a suitable position, maintains a relatively large transverse pressure counter-tightening each lateral wing 10,11 on the outer face of the platelets 8.9 and contribute to strengthening the support between the inner face of each of the platelets 8.9 with the lateral surfaces 4a and 4b of the body

heating 4.

  This is an exceptionally advantageous assembly since it contributes to both the mechanical stiffening of the device and the maintenance of optimum thermal power, which in the same space imposed by the manufacturers will lead to heating of the fuel oil. optimum in conditions

- 10 -

ideal thermal.

  According to a particular and unexpected advantage of the invention, it is pointed out that the thermal short circuit inevitably operated by the springs between the flanges 10, 11 and the casing 1 creating undeniable heat losses is, in principle, largely compensated. in that such a short circuit actually contributes to

  lowering the temperature of the CTP platelets, that is,

  to say a slight increase in their intrinsic power and it was calculated that the thermal balance

final is clearly positive.

  Finally and according to a particular variant, the corrugated spring shims 11, 12 may be replaced by shims obtained from a lamella, for example copper brass or the like, folded on itself longitudinally, the two faces being brought closer together. one of the other without contact to form a half moon in cross-section; these wedges can then be introduced by force, the plane side coming against the wings 10,11 and the

  semi-circular part against the envelope 1.

  According to a last feature of the invention, it is provided, at the end of at least one lateral wing 10, to extend it upwards in order to create an appendage 14 capable of being folded down on the upper face 4c of the body heating 4 and capture the temperature which is advantageously combined with that of the side wing from which the appendix 14; of course, the appendix 14 has a width not exceeding the width of the upper face 4c of the heating body 4 and has at least one surface capable of receiving the active face of a thermostat 15 whose closing contact setting the oil burner is established as soon as the temperature of appendix 14 corresponds to the ideal reheat temperature for the

  spraying the oil at the jet.

  Thus, initially, the heater is energized by the pins 16,17 supplying the PCT 8.9 chips, the burner is not yet powered; fuel oil

- he -

  stationing at this time in the heater just before the nozzle, begins to heat up inside the conduit 5 of the heater body 4, until a correct spray temperature is reached which will then be detected by the thermostat 15, which can then switch, that is to say, start the burner fed

by the two pins 17,18.

  In accordance with FIGS. 4 and 5, the construction of the heating body 4 with its lateral recovery wings 10, 11 and the system for connecting and mounting the plates 8, 9 around the same body will be described below. of

heater 4.

  According to FIG. 4, the heating element 4 of the heater, according to the preferred variant of the invention, is tubular in shape with a square section whose width and length of the four faces 4a, 4b, 4c, 4d will be easily determined by those skilled in the art, depending on the type of oil burner and where appropriate, taking into account the space available around said burner. The heating body 4 is, for example, obtained by spinning from a block of copper, brass or the like, traversed along its longitudinal axis by a duct 5 advantageously circular ensuring the passage of fuel oil to be heated between the pump and the nozzle (not shown) of the oil burner. Incidentally and advantageously, the conduit 5 is filled with stuffing elements 6 formed, for example, by small bronze balls held by any means such as sintering inside the conduit 5 to increase the heat exchange surfaces between the oil and the heating body 4, without too much restraining the flow of fuel oil to heat, which would cause a phenomenon of coking and would lead

  naturally to the dysfunction of the jet.

  From the lower face 4d of the body 4, are derived the two lateral wings 10,11 for pumping the calories from the outer faces of the pads

  CTP 8.9, as mentioned above.

- 12 -

  The wings 10,11 are formed from copper, bronze or brass plates whose length and width are substantially equal to the length and width of the faces of the tubular heating body 4; the thickness of the lateral flanges 10, 11 depends on the CTP plates used and their thermal power delivered; the person skilled in the art knows how to perfectly adapt the thickness of these wings to achieve an optimal pumping of the heat losses of

platelets 8.9.

  Each side wing 10,11 must come into contact

  with the outer face of the plates 8,9 which

  they must come into close contact with the lateral faces 4a and 4b of the heating body 4; this implies that the wings 10,11 are parallel to the lateral faces 4a and 4b of said body, after assembly of the

platelets 8.9.

  According to the invention, this result is obtained by thermally bonding the two wings 10,11 joined by a common base 19 whose central and horizontal portion exactly matches the lower face 4d of the heating body 4 to which said base 19 is secured by solder or equivalent. On either side of this base 19, are connected the lateral wings 10,11 which by a suitable folding can be folded vertically to bear against the outer faces of the plates 8,9; this simple assembly in theory allows the pumping of heat losses as it has been said; however, to ensure the correct final positioning, that is to say vertical in the drawings, the wings 10,11, there is provided, according to the invention, a bead 4e extending along the center line of the face lower 4d of the heating body 4, obtained simultaneously with the spinning of the body 4, to accurately position the base 19 which is provided with a recessed rib along its center line so that, fitting, it marries said bead 4th, after inserting a thin layer of solder for welding the two parts; in the same way, it is planned to

- 13 -

  preform the base of each wing; this preforming is intended to reserve material to take into account the thickness of the platelets CTP 8.9 when, for example, by pressing down according to the arrow F of FIG. 4, the flange 11 against the face external of said platelets CTP 8,9. According to a first variant, the base of each wing is preformed by a first bending downwards, from the connection line 20 to the heating body 4, then by a complete reversal according to an arc of circle of diameter equal to thickness of the plates 8, 9, the vertical and flat portion 10a, 11a of the lateral wings 10, 11 are folded, to bring them vertically and parallel to the faces 4a, 4b of the heating body 4 (this

  first variant is not shown in Figure 4).

  According to another variant of the invention, the vertical and flat portion 10a, 11a of the lateral wings 10,11 will simply be connected to the heating body 4 by preforming the connection zone consisting of two successive bends from the line connecting piece 20 to the heating body 4; the base of each wing then extends along a first surface 21 towards the outside and in the extension of the lateral contact faces 4a, 4b of the heating body 4; following a first folding made along a line 22 parallel to the connecting line 20, the wings 10,11 are folded outwards and upwards at an angle α; then a second folding along a new line 24 parallel to the two preceding 20,22 is performed in the same direction at an angle P to bring the vertical portion 10a, 11a of each wing in parallel position to the lateral surfaces 4a, 4b of the body 4 ; it will be noted that advantageously, the folding angle a is equal to 45 and the angle 3 equal to about 135; indeed, it is important that the heating body 4 is centered on the axis of the casing 1 of the heater, which leads to choose an angle of 45 so that the part 23 of the basic preforming comes to register fairly accurately on the inner wall of the casing 1. Under these conditions, a simple calculation shows that the vertical part of the preforming from the body 4 from the connecting line 20 must be of a length substantially equal to the thickness of the platelets. CTP 8,9 and similarly, the distance between the two parallel fold lines 22,24 must be equal to the thickness of the platelets CTP multiplied by V2; it follows moreover that the fold line 24 must then be substantially at the same level as the connecting line 20 (see cross section of the assembly

mounted in Figure 2).

  According to a particular characteristic of the invention, it is also planned to extend up one of the two lateral wings 10, 11, at least over part of its length to form an appendage 14 that can be folded on the face upper 4c of the heating body 4, after complete assembly of said body and its heating and feeding system, as has been said; it is a matter of sensing more precisely the temperature of said body through a thermostat 15 disposed on the upper surface of the appendix 14, to trigger the start of the burner as soon as the heating temperature of the desired oil is reached. Of course, the form of Appendix 14 depends on the form of

the bearing face of the thermostat 15.

  According to Figure 5, it will now be described the mounting of the CTP 8.9 on the heater 4

  as well as their feeding system.

  The plates are mounted on either side of the body by means of a plastic shim 25 having the general shape of a stirrup whose length is equal to the length of said body, its width and height being substantially equal to the widths of the lateral faces of the same body 4; the stirrup wedge 25 is intended to cap the heater body 4 from above. The thickness of the spacer 25 is slightly less than the thickness of the CTP plates 8, 9 so that they can be embedded therein. lateral cuts 25a, 25b made exactly to the right of the lateral bearing faces 4a, 4b of the

- 15 -

  heating body 4, without the wedge 25 prevents the wings 10,11 from coming to apply as intimately as

  possible on the active faces of the CTPs.

  The assembly and, above all, the correct and definitive positioning of the CTP plates 8, 9 are thus

  considerably facilitated by the stirrup 25.

  According to particular variants of the invention, it may be advantageous to replace one or both of the CTP 8.9 wafers by a succession, a combination, a juxtaposition or a stack of two or more wafers whose dimensions and the thermal characteristics can vary and even be very substantially different, while remaining in the dimensional space of the cutout (s) 25a and / or 25b

from the hold 25.

  For example, two or more side-by-side wafers having different temperatures can be used on a cut 25a of the shim 25 to obtain a desired final temperature, while not modifying anything on the other cut-out 25b or, on the contrary, in juxtaposing

  other elements of different characteristics or not.

  Thus, it is easier to use standardized elements, less expensive, to achieve various reheating temperatures in accordance with

user requirements.

  The electrical power supply of the CTP plates 8, 9 is advantageously, but not necessarily, via a flexible circuit 26 that envelops the wings of the plastic stirrup 25 equipped in its lateral cutouts 25a, 25b with the CTP plates 8. 9, in such a way that electrodes 27, 28 consisting for example of tin-copper or aluminum conductive thin strips printed in the flexible circuit 26 come into exact contact with the two lateral faces of the CTP plates 8, 9, as shown in FIG. FIG. 5. The flexible circuit 26 (not shown in the drawings) having printed connections supplies the electrodes 27, 28 connected in parallel, and connected to the

- 16 -

  power source of the heater.

  The steps of mounting the heater according to the preferred variant of the invention are now well understood: mounting of the CTP plates within the lateral cutouts provided in the wedging stirrer 25 preferably made of a plastic material; - Implementation of the flexible circuit 26 from enveloping the two vertical wings of the plastic caliper; the assembly is then mounted on the heating body 4, the lateral wings of the plastic stirrup 25 guiding the plates CTP and the flexible circuit 26 in the space between the pumping flanges 10, 11 and the lateral faces 4a , 4b of the heating body 4. When the stirrup 25 is in contact with the upper surface 4c of the body 4, the two flat lateral wings 10a, 11a are folded over the wings of the stirrup 25; the appendix 14 is then folded against the upper face 4c of the heating body 4 to come against the upper part of the stirrup 25; the corrugated springs 12, 13 are mounted against the external faces of the lateral flanges 10a and 11a which are provided for this purpose with notches 30 at their vertical ends for receiving the curved ends 29 of the springs 12, 13 and thus keeping them in position. place, especially longitudinally; the assembly thus formed is forced into the interior of the casing 1 of the heater: in view of the geometry of the elements in the presence, it is understood that there is automatic centering of the heating body 4 in the casing 1 at the same time; - finally, it has, thanks to a light provided for this purpose on the casing 1 (not shown in the drawings), the thermostat 15 properly connected to the circuit

flexible 26.

- 17 -

Claims (13)

  1 - Heater for oil burner comprising inside a cylindrical casing (1): - a tubular heating body (4) of highly thermally conductive material, preferably of square cross section, longitudinally traversed by at least one duct (5) of circular section provided with means (2,3,7) for the sealed coupling, on one side at a pressurized inlet of the oil to be heated and the other to the nozzle holder of the burner, - at least one platelet-shaped heating element (8,9) of the positive temperature coefficient (PTC) type fitting against at least one planar face (4a, 4b) of the tubular heater (4), and   advantageously two opposite planar faces.   - a supply circuit (26) of the CTP or - CTC, a temperature detection circuit (15) controlling the start of the burner, characterized in that at least one PTC board (8, 9) is maintained in support on at least one planar face (4a, 4b) of the heating body (4) with a preferably rectangular flange (10, 11) of highly thermally conductive material, of a width substantially equal to that of the body (4) and resulting from the zone of intersection between said plane face of the body (4a, 4b) and the immediately adjacent face (4d), said flange (10,11) extending over substantially the entire length of the heating body (4) and having a thickness to be suitably folded in external cooperation with suitable folding zones (20 to 24), against the opposite outer face of said CTP plate (8,9) and thus recover the calories diffusing to outside of it.   2 - heater according to the preceding claim characterized in that the folding zones of each wing (10,11) consist of a double preforming of their base from their connecting line (20) with the heating body (4), such as during press fitting - 18 -   lateral section (F) on a wing (10, 11), which first articulates around its connecting line (20) and then around a second line parallel to said connecting line to escape the thickness of the PTC board (8,9), comes in parallel position to the contact face (4a, 4b) of the heating body (4) while remaining in positive support on the entire outer surface of said CTP wafer.   3 - heater according to claim 1 characterized in that a reserve is provided at the base of each wing (10,11) which extends from its connecting line (20), first outward and substantially in the plane of the contact face (4a, 4b) of the heating body (4) with the plates (8,9), then performs a complete reversal substantially in a half circle of diameter normally equal to the thickness of the CTP plate (8,9) for bringing by lateral pressure (F) the contact face of the wing (10, 11) against said plate to thereby hold it against the heater (4) so that the wing remains well parallel to the contact face (4a, 4b) of the body and is in addition positively supported on the entire external surface of the body. the same CTP plate (8,9).   4 - heater according to claim 3 characterized in that the reserve is obtained by successive folds (22,24) of the wing (10,11) from its connecting line (20), to form: - a first surface (21 ) in the extension and outside of the contact face (4a, 4b) of the PTC plates (8,9) on the body, - a second surface (23) connected to the first (21) by a folding line (22) parallel to the connecting line (20) and forming therewith an angle α of about 45 to the outside, - a third surface (11a) connected to the second (23) by a fold line (24). ) parallel to the preceding and forming with the second surface (23) an angle 3 of about 135 so as to bring it back to the - 19 -   body (4) in a position substantially parallel to the contact face (4a, 4b), the width of each surface successively corresponding to the width of the platelets CTP (8,9) for the third (11a), to the thickness of the platelet multiplied by V2 about for the second (23) and about the thickness of the wafer for the first surface (21).   - Heater according to any one of   preceding claims characterized in that the wings   side (10,11) are joined by a common base (19) intimately marry the lower face (4d) of the heating body (4) to which it is connected by solder or equivalent. 6 - Heater according to one of the preceding claim characterized in that a bead (4e) extending along the center line of the lower face (4d) of the body (4) cooperates with a recessed rib, corresponding to it on the base (19) connecting the two lateral wings (10,11), a solder layer being advantageously interposed between the   face (4d) and the base (19) for welding parts.   7 - Heater according to any one of   preceding claims characterized in that   the power supply of the CTP plates (8, 9) is obtained by inserting a first electrode (27) between said wafer (8, 9) and the contact face (4a, 4b) on the body (4), the second electrode (27) being interposed between the wing (10,11) and the opposite face of the plate (8,9).   8 - heater according to claim 7 characterized in that the electrodes (27,28) are constituted by thin conductive strips for example tinned copper or aluminum, coming to cover approximately the totality   opposite active faces of the CTP platelets (8, 9).   9 - heater according to claim 8 characterized in that the electrical connections putting the pads   CTP energized are performed by a flexible circuit (26).   - Heater according to any one of - 20 -   preceding claims characterized in that the   CTP plates (8,9) are recessed according to their thickness inside cutouts (25a, 25b) of a plastic shim (25) keeping them on the one hand at insulation distance and on the other hand in an adequate position relative to the electrodes 27, 28 between the wings (10, 11) and the heating element (4), the shim (25) advantageously taking the form of a stirrup when the PTC plates (8, 9) are available on two opposite flat surfaces (4a, 4b) of the body heating (4).   11 - Heater according to any one of   preceding claims characterized in that   wing (10,11) of the heating body (4) is extended in height and over at least part of its length to form an appendix (14) capable of receiving a thermostatic sensor (15), the appendix (14) being folded against the upper face (4c) of the heating element (4), after mounting the CTP plates (8, 9) on the   or the lateral faces (4a, 4b) of the body (4).   12 - Heater according to any one of   preceding claims characterized in that the   internal conduits (5) of the heating body (4) are provided with stuffing elements (16) such as balls or the like to increase the heat exchange surface without obstruct the conduit (s) (5).   13 - Heater according to any one of   preceding claims provided with elements   heaters (8,9) on two opposite planar faces (4a, 4b) of the heating body (4) characterized in that a shim (12,13) is disposed longitudinally between the inner face of the casing (1) and the outer side face of the wings (10,11) in the folded position on the CTP plates (8,9) in contact with the heating body (4) in order to counterblock the assembly in the casing (1) and to create a thermal short circuit between it and the wings (10,11).   14 - heater according to the preceding claim characterized in that the wedges (12,13) are blades, - 21 -   preferably spring steel, longitudinal and corrugated according to their edge to provide a spring effect well distributed over the entire length of the wings (10,11) to ensure a positive and permanent contact with the CTP plates (8,9). - Heater according to claim 13 characterized in that the longitudinal wedges (12,13) are made from a longitudinally folded lamella on itself, the two faces being brought closer to one another without contact, section cross-section in the general shape of a half-moon of length normally equal to the length of the wings (10,11), the effect   spring resulting from the compression between the half   on the inner wall of the casing (1) and the flat face resting on the wings (10, 11) guaranteeing a   positive and permanent contact with the CTPs.   16 - heater according to the preceding claim characterized in that the wedges (12,13) are made of copper, brass or the like.   17 - Heater according to any one of   preceding claims characterized in that each   CTP (8,9) can result from a combination, a juxtaposition or a stack of two or more elementary wafers whose thermal characteristics may be different, the total size of said wafers remaining identical to that of each CTP (8.9).