Heating coil without reflector.
The reflectorless heating coil design addresses the issue of rear radiation in conventional heating devices by incorporating a shunt resistance in the heating coil winding, resulting in a compact, cost-effective heating solution that directs power efficiently into the room volume.
Patent Information
- Application Number
- FR2023013710
- Authority / Receiving Office
- FR · FR
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2023-12-06
- Publication Date
- 2025-06-13
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Conventional heating devices with heating coils require a reflector at the rear to redirect radiation back into the room, which increases the size and cost of the device, and necessitates high surface density and temperature of the heating element.
A reflectorless heating coil design featuring a three-dimensional winding of a single layer heating cord with a shunt resistance in parallel with the upper part of each turn, significantly reducing the rear heat emission and eliminating the need for a reflector.
The design achieves a large heating surface that emits power primarily into the room volume without the need for a rear reflector, reducing the device's size and cost while maintaining effective heating.
Smart Images
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Abstract
Description
Title of the invention: Reflectorless heating coil.
[0001] FIELD OF THE INVENTION The present invention relates to a device for the electrical heating of premises by means of a winding of an electrically heated cord also called a resistive cord, i.e. having an electrical resistance adapted to be powered by an electric generator and emitting heat in its front part and not emitting heat in the rear part of the winding.
[0002] BACKGROUND OF THE INVENTION Heating premises using electrical energy essentially uses the Joule effect in an electrical resistive element powered by electrical connectors from an electrical energy source. The transfer of heat to the premises, the air and the occupants occurs by thermal conduction and / or convection and / or infrared radiation emitted by the electrical resistive element due to its temperature.
[0003] The electrical resistive element may be in the form of a winding (coil) of a resistive cord on a core, for example made of ceramic. The core may be, for example, cylindrical in shape with a director in the form of a circle or a very flattened ellipse or a polygon with rounded corners. The core can be a solid solid body or a hollow body, generally the resistive element has proximity and / or extensive contact with the mass of the core The core may be structured, for example comprising at its periphery longitudinal beams distributed radially regularly at the vertices of a regular polygon, thus allowing support of the ribbon through contact of the ribbon with the beams and the absence of contact of the ribbon with the core in the inter-beam spaces.
[0004] The resistive cord may be, for example, non-limitingly, of cylindrical section in the case of the winding of a conductive wire bearing an insulating varnish or, for example, of rectangular section in the case of the winding of a ribbon.
[0005] A heating device with a heating coil may require a reflector located at the rear of the coil, at a distance from it and of dimensions much greater than those of the coil to return to the volume of the room the radiation emitted towards the rear by the rear part of the coil. Therefore, for a given dimensioning of the heating device, only a small part of the dimensioning corresponds to the radiation emitting surface, which implies choosing that the surface density of radiation emitted by the resistive heating element and therefore the temperature of the resistive heating element are very high so that the total flow of emitted power is sufficient.
[0006] DETAILED DESCRIPTION OF THE INVENTION The device which is the subject of the invention presented below makes it possible to heat a room in particular by infrared radiation while avoiding the aforementioned drawback in the sense that it makes it possible to create a large heating surface emitting the power essentially towards the volume of the room, without the need for a thermal reflector at the rear of the heating element.
[0007] The device which is the subject of the invention consists of at least one three-dimensional winding of a single layer of a heating cord capable of being supplied by means of electrical connectors outside the scope of the invention, from an electrical energy source outside the scope of the invention, preferably in the form of a ribbon, made of electrically conductive material of N turns of pitch p on a core where a single layer means that the possible overlap between two consecutive turns is less than half the width of the cord. A plane passing through the axis of the winding conventionally delimits two complementary parts of the winding. A part of said winding, called the lower part, is intended to be oriented towards the volume of the room and the other part called the upper part is intended to be oriented towards the ceiling or one of the walls of the room.
[0008] An example of a heating cord winding is a winding of a circular cupro-nickel wire section of 1 mm in diameter with a pitch of 2 mm. Another example of a resistive cord winding is a winding of a stainless steel or aluminum alloy ribbon where the width of the ribbon is between 25 mm and 50 mm, typically having the value of 30 mm, and where its thickness is between 15 micrometers and 100 micrometers, typically having the value of 20 micrometers with a pitch of 35 mm. Another example of a resistive cord winding is a ribbon of polymeric material such as polypropylene or PET or Teflon, 50 micrometers thick and 25 mm wide, aluminized on at least one of its faces to a thickness of 5 micrometers. The turns of said winding are electrically isolated from each other, that is to say that there is no electrical conduction path between any two turns other than possibly between the start of one turn and the end of the previous one or vice versa between the end of one turn and the start of the next one, this condition being able to be obtained for example by choosing a pitch p of the winding greater than the width of the resistive cord.
[0009] The device which is the subject of the invention is characterized in that: the electrical resistance of the greater part of each turn included within the limits of the upper part of the winding, called the upper part of the turn, is placed in parallel with a shunt resistance preferably of significant value tively weaker than that of the upper part of the turn which itself is substantially identical to that of the lower part so as to obtain an upper electrical conduction path consisting of the upper part of the turn in parallel with the shunt resistor, having a resistance significantly lower than the resistance of the lower part of the turn, that is to say of the portion of the turn included within the limits of the lower part of the winding. Thus the upper electrical conduction path which is traveled by the same current as the lower part of the turn but under a much lower voltage does not heat up or much less than the lower parts of turns, its temperature rises only very little and the heat emitted towards the rear is extremely low.This avoids the need to use a reflector at the rear of the winding to return the very small amount of residual radiation corresponding to the volume of the room.
[0010] An exemplary embodiment of the shunt resistor consists of a layer of conductive material, for example aluminum, silver or copper in electrically conductive contact with at least one of the surfaces of the upper parts of the turns (figures 1A to 1C) and (figures 3A to 3C). This contact layer may result from a deposition capable of being carried out by techniques known to those skilled in the art, such as electrolytic deposition, electroless deposition, evaporation, spraying, painting. Another example of the realization of the shunt resistance in the case of a ribbon cord on a cylindrical core is a sigmoid-shaped rod (figures 2A to 2C) made of copper or brass joining the beginning of each upper turn to the end of the upper part of the same turn, through the core which is here preferably a hollow shell provided with holes for the crossing of said sigmoid rod. The electrical junction between the ends of the copper wire and the ribbon cord is made by the contact support of the underside of the ribbon cord on the ends of the copper or brass sigmoid rod. The sigmoid shape of the rod allows it to be inserted into its position by pre-compressing it and also allows, due to the residual pre-compression, to create a support force of the rod on the underside of the ribbon cord. The value of the shunt resistance is for example nine times lower than the value of the resistance of the upper part of the coil, which thus creates a higher electrical conduction path with resistance ten times lower than that of the upper part of the coil. The cord winding is electrically insulated from the core in that said core does not create an electrical path that could divert a portion of the electric current flowing in the cord either because the core is made of insulating material and or because there is an insulating material between the cord and any portion of the core supporting the insulating cord. The shape of the turns is preferably oblong so that the winding has in its lower part a radiating surface of large extension while keeping a limited vertical dimension.
[0011] In an exemplary embodiment known as a parallelepiped shape with rounded ends (figures 1A to 1C), each turn is inscribed on a volume consisting of a rectangular parallelepiped volume of large horizontal extension and much lower vertical height, two of the opposite vertical faces of which are each joined to a semi-cylindrical volume of diameter equal to the height of said face
[0012] In another exemplary embodiment, each turn is inscribed on an ellipsoid with a major horizontal axis much larger than the minor vertical axis (figures 3A to 3C); for example, the major axis is ten times larger than the minor axis.
[0013] BRIEF DESCRIPTION OF THE DRAWINGS Other objects, characteristics and advantages of the invention will be better understood in light of the detailed description which follows, with reference to the appended drawings in which:
[0014] Figures 1A to 1C represent an embodiment of the invention where the heating cord (101) is of cylindrical section on a core (102) of parallelepiped type having a flat extended surface (1021) between two rounded ends (1022) and where the shunt resistance is a layer of conductive metal (103) on the upper part of each turn [Fig.lA] shows the said core (102). [Fig.lB] shows the upper part of the heating cord (101) installed on the core (102) and covered with the layer of conductive metal (103) performing the shunt resistance. [Fig.lC] shows the lower part of the heating cord (101) installed on the core (102)
[0015] Figures 2A to 2C show an embodiment of the invention where the heating cord is a flat ribbon (201) wound on a cylindrical core (202) pierced with passages for the sigmoid-shaped rods (204) which are the shunt resistance connecting the start of the upper part of each turn of the ribbon (201) to the end of this same upper part through the core (202). [Fig.2A] shows the flat ribbon (201), the cylindrical core (202) and a sigmoid-shaped rod (204) as separate and spaced pieces. [Fig.2B] shows the flat ribbon (201) installed on the cylindrical core (202). [Fig.2C] is an exploded view to allow a good visualization of the assembly of the flat ribbon (201) on the core (202) with the set of sigmoid-shaped rods (204) connecting the start of the upper part of each turn to the end of this same upper part through the core (202).
[0016] Figures 3A to 3C show an embodiment of the invention where the heating cord is a flat ribbon, the core section is of elongated elliptical shape and the shunt resistor is a layer of conductive metal on the top of each coil . [Fig.3A] shows the elliptical cross-section core (302). [Fig.3B] describes the flat ribbon (301) as it appears once wound on the core (302) which is not shown here and without the conductive metal layer on the upper part of the coils. [Fig.3C] represents the flat ribbon (301) as it appears once wound on the core (302) and with the conductive metal layer (303) (the thickness of which has been deliberately accentuated for better readability) on the upper part of the coils
Claims
Claims
1. An electric heating device consisting of at least one single-layer three-dimensional winding of an electrical resistive cord on a core where the winding comprises N turns electrically insulated from each other and electrically insulated from the core, characterized in that: the electrical resistance of at least a portion of each upper portion of the turns is paralleled with a shunt resistor so as to obtain an electrical conduction path having a resistance significantly lower than the resistance of the lower portion of the turns
2. Claim according to 1 wherein the shunt resistor is an electrical conductor connecting the ends of the upper part of the turns
3. Claim according to 1 to 2 where the shunt resistor is a layer of conductive material on at least one of the faces of the upper part of the turns.
4.
5. Claim according to 1 to 3 where the resistive cord is a ribbon. Claim according to 4 where the ribbon is made of aluminum alloy or iron alloy or aluminized polymeric material.
6. Claim according to 4 and 5 where the width of the tape is between 25mm and 50mm and where its thickness is between 15 micrometers and 100 micrometers.
7. Claim according to 1 to 2 where the core is a hollow cylinder whose wall is pierced with openings for the passage of electrical conductors performing the shunt resistance
8. Claim according to 1 to 6 where the core is of parallelepipedal shape with rounded edges
9.
10. Claim according to 1 to 6 wherein the core is of elongated elliptical shape. Claim according to 1 to 2 wherein the electrical conductor connecting the ends of the upper longitudinal part is a metal rod of sigmoidal shape