FR2718317A1 - Combination of building elements. - Google Patents

Abstract

Combination of building elements for electric heating plates, ignition devices, temperature sensors or the like, comprising an electric resistant element (3), an electrically insulating layer (2) and a heat transfer plate (1) in one material of complex matrix metal type (MMC).

Description

Combination of building elements The object of the present invention

  is a combination of building elements for electric heating plates, ignition devices, temperature sensors or the like, arranged one above the other and comprising an electric resistance element, a

  insulating layer of electricity and a heat transfer plate.

  In principle, such a combination of construction elements is carried out in any heating or baking panel customary hitherto, for which below a heat carrier is provided a heating spiral which is separated from the heat carrier by a gap

air or insulating air gap.

  The thermal transfer between the heating spiral and the air, as well as air to the heat transfer plate and relatively bad, which is why thermal losses

  considerable are observed in these constructions.

  He was therefore tempted to replace the gap

  air through a layer of solid insulating material.

  Molded metallic materials, which are generally used as heat transfer plates, cannot, however, with regard to their thermal expansion properties, be ill-suited to solid insulating materials, so that a combination of construction elements with a insulating layer consisting of a solid has been practically impossible so far, due to the manifestation of high thermal stresses. The object of the present invention is to improve this type of

  construction from a technological, thermal point of view.

  To achieve this goal, it is proposed according to the invention that the heat transfer plate is made at least in part, preferably entirely, of a material

  metal matrix composite (MMC).

  This material, which for other applications, is known among other things for the manufacture of electronic chip cases in the electronic industry, consists of a reinforcing material, soaked or infiltrated by a

matrix metal.

  Thanks to the choice made each time for the reinforcement component and the metal, one can exercise at will, as regards their mechanical as well as thermal properties. It is certainly also possible to obtain an adaptation of the thermal expansion properties of the

  heat transfer plate to those of an insulating material.

  This is why, according to a preferred embodiment of the invention, the electrically insulating layer, in the context of combinations of building elements of the type mentioned at the beginning, consists of a solid electrical insulator and no more air, in particular the material of the MMC plate and the material of the electrically insulating layer having coefficients of thermal expansion which are substantially suitable

to one another.

  Thanks to this combination of building elements, it is possible to use a

  thin film structure, preferably based on silicon.

  In practice, an insulating material, the dimensions of which correspond substantially to those of the resistant element, is applied to the heat-carrying plate or in cavities thereof. Therefore, the cost of the insulating material is kept low, which acts favorably in the price of the combination elements manufactured. Another embodiment of the invention may consist in that the insulating layer is produced in the form of an insulating plate, integrated on one face of the heat-carrying plate and on which the element is applied.

  resistant, for example by plating or soldering.

  Therefore, the heat transfer plate and the insulation can be manufactured jointly. The integration of the insulating plate is best effected by means of a metal bond, which is formed during the infiltration of the reinforcing material by the matrix material. The infiltration is preferably carried out in a manner which causes overmolding, so that a surface layer is formed from

matrix metal.

  An improvement of the invention can consist in that all the resistant elements and the tracks

  conductive for the power supply of those

  these are arranged on a common insulating layer.

  As a result, manufacturing costs can be reduced and certain steps in the process can be saved. According to another embodiment of the invention, it can be provided that the conductive tracks of the resistive element consist of a molded metal layer

on the insulating layer.

  On the other hand, however, it is also possible to provide in the insulating layer cavities in the form of grooves which fill with metal during the infiltration process and can be used as electrical supply conductors and

of departure.

  Therefore we can then machine with removal of material the surface of the MMC body, the metal remaining in the grooves used to form the lines

power supply.

  The power supply lines for the resistive element can, according to another embodiment of the invention, be manufactured by local removal of a surface metal layer which comes from overmolding taking place simultaneously with infiltration by

of the metal of the MMC material.

  According to an improvement of the invention, the MMC material used as reinforcement is a ceramic based on oxide, carbide and / or nitride, such as for example silicon carbide, aluminum nitride, beryllium oxide, aluminum oxide, boron nitride or carbon and / or a metal, for example molybdenum, with a higher melting point than that of

matrix metal.

  The metallic component of the MMC material can, according to one embodiment of the invention, consist of one or more metals from the aluminum, iron, nickel group,

  cobalt, silicon, copper, molybdenum or their alloys.

  The MMC material has channels filled with metal,

  connecting for example together faces of opposite plates.

  During the infiltration of the metal, these holes or channels fill with the metal and then constitute heat conducting bridges, with the help of which a faster evacuation or distribution of the

  heat in the desired direction.

  The material of the electrically insulating layer is a ceramic based on oxide, carbide and / or nitride, such as for example aluminum nitride, aluminum oxide or beryllium oxide, or a temperature-resistant synthetic material, insulating

  electricity, such as polybenzimidazol (PBI).

  Apart from the thin-film structures based on silicon, according to another variant of the embodiment, an element based on a ceramic with a PTC or NTC characteristic can be used as the resistant element. These types of ceramics are made of materials with temperature dependent conductivity coefficients and can

  be used to advantage in this regard.

  Another characteristic of the invention may also consist in that the resistant element is

  made as a heating element.

  The production of the conductor ribs can then in known manner be done by photolithography, bite

  chemical, laser beam machining or the like.

  According to another embodiment of the invention, the heat transfer plate can be provided with a sealing ring. The heat transfer plate can therefore be integrated

and thermally insulated.

  If the combination of construction elements according to the invention is used as a cooking plate, the surface layer of the heat-transfer plate advantageously has on the face opposite to the heating elements, a layer intended to increase the mechanical resistance, respectively to increase the polish and to

  intensify contact with an object to be placed on it.

  To manufacture the combination of building elements according to the invention, these components can be assembled to each other individually, or else there can be joint prefabrication of the combination consisting of a heat transfer plate and the insulation and then application of the resistant element for example by

plating or soldering.

  An embodiment of a heating and cooking plate according to the invention is shown in the drawings

  annexed with the aid of which the invention is better illustrated.

  In the drawing: FIG. 1 represents a combination of construction elements seen from below FIG. 2 represents a section along line II of FIG. 1 FIG. 3 represents another embodiment of a combination of construction elements according to the invention, seen from below, and FIG. 4 represents a section along the line IV-IV of FIG. 3 FIG. 1 represents a combination of building elements according to the invention, being in the form of a heating plate 1 in the form of a panel, shown in bottom view with respect to its position of use. The heating plate 7 consists of a heat transfer plate 1 and on its underside are introduced rectangular insulating plates 2, arranged in a star, which are integrated into cavities on the underside of the heat transfer plate 1, until filling

the area of a face.

  The heat transfer plate 1 is made of a Composite MétalMatrice (MMC) material, while the insulating layers are made of an electrically insulating material, such as, for example, a ceramic based on oxide, carbide, nitride, such as aluminum nitride, aluminum oxide or beryllium oxide or a heat-resistant and electrically insulating synthetic material such as polybenzimidazole (PBI), on surfaces , opposite to the heat transfer plate 1, to which are applied

  resistant elements 3 of surface.

  As reinforcement, the MMC material may for example contain a ceramic based on oxide, carbide and / or nitride, such as aluminum nitride, aluminum oxide or beryllium oxide and its component. metallic may for example consist of one or more metals belonging to the group aluminum, iron, nickel, cobalt, silicon, copper or their alloys. The metal-matrix compound of the heat transfer plate 1 and the insulating plates 2 then have coefficients of thermal expansion which are substantially adapted to one another, so that the pressure of thermal stress can be avoided. As a reinforcement, it is also possible to use a metal, for example molybdenum, which has a melting point.

  higher than that of the matrix metal.

  The MMC material can be provided, before the infiltration by the piercing metal, respectively, of channels 9 as indicated in FIGS. 2 and 4 which connect together, for example two or more faces. During metal infiltration, these holes or channels are filled with the matrix metal and then constitute heat conducting bridges, by means of which a faster distribution or evacuation of heat takes place in directions. which can be predetermined by the arrangement of the holes or channels. The resistive elements 3 then consist of a thin film structure based on silicon, but it is however also possible to use other suitable thin film materials. As can be seen in FIGS. 1 and 2, the insulating plates 2 and the resistive elements 3 are roughly the same size, the insulating plates 2 extending into insulating tracks 8, extending radially in the direction of the conductive track. 4 and on which run conductive ribs 4 'connected to the annular conductive track 4 and the central conductive track 4. The type of process for applying the resistant elements 3 to the insulating layers 2 can be of different types, for example by plating or brazing. On the surface of these insulating plates 2 are the resistant elements 3 which are made as heating elements. The heating elements 3 are electrically supplied via conductive tracks 4 made to act as supply and discharge lines and which are arranged on the insulating tracks and which are made of the metal of the MMC material, the heating elements 3 being connected in parallel electrically. The resistant elements can however also be made from a ceramic with a coefficient of PTC or NTC type, so that their known properties can be used to obtain a

temperature stabilization.

  To improve the mounting of the heating plate 7 in a support device, such as in a stove or the like, and to better thermally insulate the latter, the heat transfer plate 1 has a seal 5 inserted in it. This can be manufactured jointly at the stage of manufacturing the plate, or else be

inserted afterwards.

  2 shows a section of the plate 7 of Figure 1 along the line II-II. It is clearly seen that the insulating plates 2 are arranged in a cavity of the heat-carrying plate 1, so that it is integrated as far as one side in the MMC plate. The heating element 3 is connected to the electrical supply lines and

  evacuation 4 arranged on the insulating tracks 8.

  Figure 3 and Figure 4 show another embodiment for which the construction elements coinciding with those of Figures 1 and 2 are provided with the same reference characters. Unlike Figures 1 and 2, the heat transfer plate 1 carries a continuous insulating layer 10, on which are arranged the conductive tracks 4 respectively the ribs

  conductive 4 'and the heating elements 3.

  The conductive tracks 4, respectively the conductive ribs 4 'and the heating elements 3, are produced by local removal, for example by chemical bite or the like of a surface metal layer, which comes from overmolding taking place simultaneously with infiltration by metal of the MMC material. As an alternative to this, cavities, such as for example grooves, can be provided in the insulating layer 10, and be filled during the process of infiltration by the matrix metal and be usable as supply and evacuation lines. , since after this process the surface of the MMC body can be machined with removal of material, the metal remaining in the grooves is then used to form the power supply and discharge lines. The heat transfer plate 2 can either be made entirely of the metal-matrix composite material, this being represented by FIGS. 1 and 2, or simply have a core 1 "made of such a material and which is embedded in the matrix material, this being shown

  by way of example in FIGS. 3 and 4.

  For domestic use, the heat transfer plate 1 has, on the face opposite to the face carrying the insulating layers 2, a surface layer 6 which serves to increase the mechanical resistance, to increase the polish and to intensify the contact, therefore to increase heat transfer to objects placed on it, such as

saucepans and the like.

  We also see the seal 5 which is provided to allow an isolated incorporation of the heating plate. The combination of building elements according to the invention is more compact than the previously known elements, because it has no air interstice and it fulfills its function with relatively small heating and insulating elements. It has extremely low heat losses, which help ensure faster heating and conditions

  more user friendly.

  The combination according to the invention can be used with the same advantages as an ignition device, for example for safety airbags for cars or the like, as well as

temperature.

Claims (18)

  1. Combination of building elements for electric heating plates, ignition devices, temperature sensors or the like, comprising arranged one above the other an electric resistant element, an electrically insulating layer and a heat transfer plate, characterized in that the heat transfer plate (1) is made at least in part and preferably entirely of a material   metal matrix composite (MMC).   2. Combination of building elements according to claim 1, characterized in that the electrically insulating layer (2; 10) consists of a solid electrically insulating.   3. Combination of building elements according to claim 2, characterized in that the material of the MMC plate (1) and the material of the electrically insulating layer (2; 10) have coefficients of   thermal expansion substantially adapted to each other.   4. Combination of building elements according to   one of claims 1 to 3, characterized in that   the resistant element (3) consists of a structure with   thin layer preferably based on silicon.   5. Combination of building elements according to   one of claims 1 to 4, characterized in that the   insulating layer (2) corresponds to its dimensions   substantially to those of the resistant element (3).   6. Combination of building elements according to claim 5, characterized in that the insulating layer (2) is produced in the form of an insulating plate, integrated on one face in the heat-carrying plate (1) and on which the resistant element ( 3) is applied, for example plated or brazed.   7. Combination of construction elements according to claim 5, characterized in that all the resistant elements (3) and the conductive tracks (4) intended for the electrical supply of these are arranged on a common insulating layer (10).   8. Combination of construction elements according to   any one of claims 1 to 7, characterized in   that in the insulating layer (2; 10) are provided groove-shaped cavities, which fill with metal during the infiltration process and are usable   as power supply lines.   9. Combination of building elements according to   any one of claims 1 to 8, characterized in   that the conductive tracks (4) of the resistant element (3) consist of a metal layer molded on the insulating layer (2; 10).   10. Combination of construction elements according to claim 9, characterized in that the conductive tracks (4) are produced by local removal of a surface metal layer which comes from overmolding, taking place during infiltration with metal. , of MMC material.   11. Combination of building elements according to   any one of claims 1 to 10, characterized in   what the MMC material comprises as reinforcement a ceramic based on carbide oxide and / or nitride, such as for example silicon carbide, aluminum nitride, beryllium oxide, oxide of aluminum, boron nitride or carbon and / or a metal, for example molybdenum, with a higher melting point than that of matrix metal.   12. Combination of construction elements according to   any one of claims 1 to 11, characterized in   that the metallic components of the MMC material consist of one or more metals from the group consisting of aluminum, iron, nickel, cobalt, silicon,   copper, molybdenum or their alloys.   13. Combination of construction elements according to   any one of claims 1 to 12, characterized in   that the MMC material has channels (9) filled with metal, interconnecting for example opposite faces of the plate. 14. Combination of construction elements according to   any one of claims 1 to 13, characterized in   that the material of the electrically insulating layer (2; 10) is a ceramic based on oxide, carbide and / or nitride, such as for example aluminum nitride, aluminum oxide or l beryllium oxide, or a temperature-resistant synthetic material, insulating   electricity, such as polybenzimidazol (PBI).   15. Combination of construction elements according to   any one of claims 1 to 14, characterized in   that the resistant element (3) is an element based on a   ceramic with PTC or NTC characteristic.   16. Combination of building elements according to   any one of claims 1 to 15, characterized in   that the resistant element (3) is made as a heating element. 17. Combination of building elements according to   any one of claims 1 to 16, characterized in   that the heat transfer plate (1) is provided with a ring sealing (5).   18. Combination of building elements according to   any one of claims 1 to 17, characterized in   that the heat transfer plate (1) is provided, on the face opposite to the heating elements, with a layer (6) intended to increase the mechanical resistance, respectively to increase the polish and to intensify the contact with an object to place on it.