Heating device equipped with a door comprising a triple glazing

Abstract

A heating device equipped with a chamber defining a cavity, includes a door or wall incorporating a triple glazing including three transparent substrates defining, from the interior to the exterior of the cavity, faces numbered 1 to 6 respectively, at least the faces 1 and 2 of the first substrate and 3 and/or 4 of the second substrate being covered with heat-reflecting coatings, wherein the mean spacing e1 between the first substrate and the second substrate and the mean spacing e2 between the second substrate and the third substrate is different, the ratio between the largest spacing and the smallest spacing being greater than 1.1, and e1 and e2 being between 2 and 20 mm.

Claims

1. A heating device equipped with a chamber defining a cavity, said device comprising a door or wall incorporating a triple glazing comprising first, second and third transparent substrates defining, from an interior to an exterior of the cavity, six faces numbered 1 to 6 respectively, at least the faces 1 and 2 of the first substrate and 3 and/or 4 of the second substrate being covered with heat-reflecting coatings, wherein a mean spacing e.sub.1 between the first substrate and the second substrate and a mean spacing e.sub.2 between the second substrate and the third substrate is different, a ratio between a largest spacing of one of e.sub.1 and e.sub.2 and a smallest spacing of the other one of e.sub.1 and e.sub.2 being greater than 1.1, e.sub.1 and e.sub.2 being between 2 and 20 mm, and wherein e.sub.1>e.sub.2.

2. The heating device as claimed in claim 1, wherein faces 1 and 2 of the first substrate and face 3 of the second substrate are covered with heat-reflecting coatings, faces 4 to 6 being free of such coatings.

3. The heating device as claimed in claim 1, wherein e.sub.1 and e.sub.2 are between 4 and 15 mm.

4. The heating device as claimed in claim 1, wherein the triple glazing comprises: a) for the first substrate in contact with the cavity: on the face 1, turned toward the interior of and in direct contact with said cavity, a first stack that reflects heat essentially by means of one or more functional layers based on a transparent conductive oxide, on the other face 2, turned toward the exterior of said cavity, a second stack that reflects heat essentially by means of one or more functional layers based on a metal chosen from gold or silver, b) for the second substrate: on the face 3 turned toward the interior of said cavity, a third stack that reflects heat essentially by means of one or more functional layers based on a transparent conductive oxide, the face 4 of the second substrate being free of a heat-reflecting coating, the faces 5 and 6 being free of a heat-reflecting coating.

5. The heating device as claimed in claim 1, wherein the multiple glazing comprises: a) for the first substrate in contact with the cavity: on the face 1, turned toward the interior of and in direct contact with said cavity, a first stack that reflects heat essentially by means of one or more functional layers based on a transparent conductive oxide, on the other face 2, turned toward the exterior of said cavity, a second stack that reflects heat essentially by means of one or more functional layers based on a metal chosen from gold or silver, b) for the second substrate: on the face 3 turned toward the interior of said cavity, a third stack that reflects heat essentially by means of one or more functional layers based on a metal chosen from gold or silver, the face 4 of the second substrate being free of a heat-reflecting coating, the faces 5 and 6 of the third substrate being free of a heat-reflecting coating.

6. The heating device as claimed in claim 1, wherein the first coating on the first face 1 of the first substrate comprises, as functional layer, an indium tin oxide, the atomic percentage of Sn of which in the oxide is within a range extending from 5% to 70%.

7. The heating device as claimed in claim 1, wherein the first coating on the first face 1 of the first substrate comprises, as functional layer, an indium tin oxide comprising a proportion by weight of around 85% to 95% of indium oxide and around 15% to 5% of tin oxide.

8. The heating device as claimed in claim 1, wherein the first coating on the first face 1 of the first substrate comprises, in succession, starting from the substrate: at least one underlayer of a dielectric compound chosen from silicon nitride, silicon oxide or zinc tin oxide, an ITO functional layer, and at least one overlayer of a dielectric compound chosen from silicon nitride, silicon oxide, or zinc tin oxide.

9. The heating device as claimed in claim 1, wherein the first coating on the first face 1 of the first substrate comprises, in succession, starting from the substrate: at least one underlayer of a dielectric compound chosen from silicon nitride, silicon oxide or zinc tin oxide, a first ITO functional layer, an intermediate layer of a dielectric compound chosen from silicon oxide, silicon nitride or zinc tin oxide, a second ITO functional layer; and at least one overlayer of a dielectric compound chosen from silicon nitride, silicon oxide, or zinc tin oxide.

10. The heating device as claimed in claim 1, wherein the second coating on the face 2 of the first substrate comprises at least one silver-based functional metal layer and at least two dielectric assemblies, each dielectric assembly comprising at least one dielectric layer, so that each silver-based layer is positioned between two dielectric layers.

11. The heating device as claimed in claim 1, wherein the third coating on the face 3 of the second substrate or on the face 4 of the second substrate comprises at least one silver-based functional metal layer and at least two dielectric assemblies, each dielectric assembly comprising at least one dielectric layer, so that each silver-based layer is positioned between two dielectric layers.

12. The heating device as claimed in claim 1, wherein at least the coated substrate of the stack is curved and/or tempered and wherein all the substrates of the glazing are tempered.

13. The heating device as claimed in claim 1, wherein the ratio between the largest spacing of one of e.sub.1 and e.sub.2 and the smallest spacing of the other one of e.sub.1 and e.sub.2 is greater than 2.

14. A door or wall for a heating device comprising a triple glazing, the triple glazing including first, second and third transparent substrates which define, from an interior to an exterior of the cavity of said device, six faces numbered 1 to 6 respectively, at least the faces 1 and 2 of the first substrate and 3 of the second substrate being covered with heat-reflecting coatings, wherein a mean spacing e.sub.1 between the first substrate and the second substrate and a mean spacing e.sub.2 between the second substrate and the third substrate is different, a ratio between a largest spacing of one of e.sub.1 and e.sub.2 and a smallest spacing of the other one of e.sub.1 and e.sub.2 being greater than 1.1, and wherein e.sub.1>e.sub.2.

15. The door or wall for a heating device as claimed in claim 14, wherein the faces 1 and 2 of the first substrate and face 3 of the second substrate are covered with heat-reflecting coatings, the faces 4 to 6 being free of such coatings.

16. The door or wall for a heating device as claimed in claim 14, wherein said triple glazing comprises: a) for the first substrate in contact with the cavity: on the face 1, turned toward the interior of and in direct contact with said cavity, a first stack that reflects heat essentially by means of one or more functional layers based on a transparent conductive oxide, on the other face 2, turned toward the exterior of said cavity, a second stack that reflects heat essentially by means of one or more functional layers based on a metal chosen from gold or silver, b) for the second substrate: on the face 3 turned toward the interior of said cavity, a third stack that reflects heat essentially by means of one or more functional layers based on a transparent conductive oxide.

17. The door or wall for a heating device as claimed in claim 16, wherein said triple glazing comprises: a) for the first substrate in contact with the cavity: on a first face 1, turned toward the interior of and in direct contact with said cavity, a first stack that reflects heat essentially by means of one or more functional layers based on a transparent conductive oxide, on the other face 2, turned toward the exterior of said cavity, a second stack that reflects heat essentially by means of one or more functional layers based on a metal chosen from gold or silver, b) for the second substrate: on the face 3 turned toward the interior of said cavity, a third stack that reflects heat essentially by means of one or more silver-based functional layers.

Description

(1) Various embodiments of the present invention are presented below in connection with FIG. 1 which is appended hereto:

(2) FIG. 1 illustrates an example of a heating device comprising a triple glazing according to the invention.

(3) The triple glazing according to FIG. 1 comprises three glass substrates positioned parallel and thus defining, from the interior to the exterior of the cavity of the device, six successive glass surfaces conventionally denoted 1 to 6 from the interior to the exterior. Between the first glass substrate and the second glass spacing, a spacing e.sub.1 was made. Between the first glass substrate and the second glass spacing, a spacing e.sub.2, different from e.sub.1 was made. The spacings between substrates are filled with air at ambient pressure and in fluid communication with the outside. Three configurations according to the invention are represented in FIG. 1:

(4) a) a spacing e.sub.1 of 14 mm and a spacing e.sub.2 of 5 mm (conf. 1).

(5) b) a spacing e.sub.1 of 12 mm and a spacing e.sub.2 of 7 mm (conf. 2).

(6) c) a spacing e.sub.1 of 5 mm and a spacing e.sub.2 of 14 mm (conf. 3).

(7) According to the comparative configuration 4 (conf. 4), the three substrates are spaced apart by the same distance of 9.5 mm.

EXAMPLES

(8) In all the examples which follow, oven doors comprising a triple glazing and in accordance with the configurations described above in relation to FIG. 1 were manufactured.

(9) More specifically:

(10) Stacks of thin layers as defined below were deposited on a first substrate made of 4 mm-thick clear soda-lime glass:

(11) A stack in accordance with example 1 of patent application WO 2015/033067 was deposited on a first face 1 of the substrate.

(12) More specifically, the following stack A was deposited by AC magnetron sputtering on a 4 mm-thick clear soda-lime-silica glass substrate:

(13) Glass/SiN.sub.x (2 nm)/SiO.sub.2 (34 nm)/ITO (118 nm)/SiN.sub.x (6 nm)/SiO.sub.2 (65 nm)/TiO.sub.2 (3 nm).

(14) The numbers between parentheses correspond to the physical thicknesses deposited for each layer, expressed in nanometers.

(15) The layers of silicon oxide and of silicon nitride were deposited using silicon targets doped with (8 at %) aluminium, in an argon plasma with addition of oxygen and nitrogen respectively. The ITO layers were deposited using ITO targets in an argon plasma. The ITO layer consists of a mixture of indium (III) oxide (In.sub.2O.sub.3) and tin (IV) oxide (SnO.sub.2), the proportion by weight of the first being around 90% and the proportion by weight of the second round 10%. The SiN.sub.x barrier layer was deposited under a pressure of 2.0 pbar. The normal emissivity of this stack, as measured according to standard FR-EN 12898, was 18%.

(16) On the second face 2 of this first substrate, the following stack B, comprising a silver functional layer, and the normal emissivity of which was 3%, was deposited using conventional sputtering deposition techniques:

(17) Glass/SiN.sub.x (30 nm)/ZnO (5 nm)/NiCr (0.5 nm)/Ag (12 nm)/NiCr (0.5 nm)/ZnO (5 nm)/SiN.sub.x (30 nm)/TiO.sub.2 (3 nm).

(18) As second substrate, use was made of a substrate sold by AGC under the reference Planibel G®, comprising a 4 mm-thick clear soda-lime-silica glass sheet, on one face of which a coating C, consisting of a layer of fluorine-doped tin oxide, was deposited by pyrolysis-CVD.

(19) The third substrate was a 4 mm-thick clear soda-lime-silica glass sheet, the faces of which were bare, i.e. not covered with the above coatings.

Examples 1 to 3 (According to the Invention)

(20) Oven doors were manufactured according to the techniques of the art that comprise the assembling of the three glass substrates described above according to the configurations A to C described in connection with FIG. 1, including: a first substrate as described above comprising the coating A on face 1 and the coating B on face 2 of the door, the Planibel G® second substrate, in such a way that the coating C is oriented toward the interior of the door, i.e. is on face 3 of the triple glazing and of the door, then the third glass substrate, the bare faces of which are faces 5 and 6 of the triple glazing (cf. FIG. 1) and of the door.

(21) According to example 1, a spacing e.sub.1 of 14 mm was made between the first two substrates and a spacing e.sub.2 of 5 mm was made between the second and third substrates.

(22) According to example 2, a spacing e.sub.1 of 12 mm was made between the first two substrates and a spacing e.sub.2 of 7 mm was made between the second and third substrates.

(23) According to example 3 a spacing e.sub.1 of 5 mm was made between the first two substrates and a spacing e.sub.2 of 14 mm was made between the second and third substrates.

Example 4 (Comparative)

(24) According to this example 4, the same manufacturing steps as examples 1 to 3 were reproduced, but the three glass substrates were spaced apart by the same distance of 9.5 mm.

Example 5 (Comparative)

(25) According to this example 5, this time a quadruple glazing was assembled for the manufacture of the oven door by repeating the configuration from example 4 to which a fourth glass substrate was added on the exterior side, the fourth substrate being a 4 mm-thick clear glass substrate, the faces of which are bare, each substrate being spaced apart from the next by a distance of 6 mm so as to retain a door thickness comparable to the preceding examples.

Example 6 (Comparative)

(26) According to this example 6, this time a triple glazing was assembled for the manufacture of the oven door, using three Planibel G® substrates. The Planibel substrates were all oriented in such a way that the coating C was turned toward the interior of the door, i.e. the coating C was positioned on face 1, 3, and 5 of the triple glazing. According to this example 6, a spacing e.sub.1 of 14 mm was made between the first two substrates and a spacing e.sub.2 of 5 mm was made between the second and third substrates.

Example 7 (Comparative)

(27) According to this example 7, this time a quadruple glazing was assembled for the manufacture of the oven door, using three Planibel G® substrates as described in example 6. The Planibel substrates are used as the first three substrates of the quadruple glazing. They are all oriented in such a way that the coating C is turned toward the interior of the door, i.e. the coating C is positioned on face 1, 3, and 5 of the quadruple glazing, the fourth substrate being a 4 mm-thick clear glass substrate, the faces of which are bare. The substrates are spaced apart by the same distance of around 6 mm.

(28) The cavity of an oven equipped with resistors and provided with various doors according to examples 1 to 6 was then heated at a temperature of the order of 430° C. The results are reported in table 1 below:

(29) In table 1, a face coated with the stack A (comprising the ITO functional layer) is denoted A, a face coated with the stack B (comprising the silver functional layer) is denoted B, a face coated with the coating C (comprising the pyrolytic SnO.sub.2:F layer) is denoted C and an uncoated face is denoted X.

(30) It is indicated that, according to the GIFAM (Groupement Interprofessionnel des Fabricants d'Appareils d'Equipement Ménager [Interprofessional Group of Domestic Appliance Manufacturers]), the maximum temperature of the exterior wall of the door of an oven must never exceed 70° C. in order for the appliance to be considered a “cold door” appliance.

(31) TABLE-US-00001 TABLE 1 Average Exterior T° of wall the cavity temperature Example F1 F2 F3 F4 F5 F6 F7 F8 e.sub.1 e.sub.2 e.sub.3 (° C.) (° C.) 1* A B C X X X — — 14 5 — 430 67 2* A B C X X X — — 12 7 — 430 70 3* A B C X X X — — 5 14 — 430 70 4 A B C X X X — — 9.5 9.5 — 430 77 5 A B C X X X X X 6 6 6 430 65 6 C X C X C X — — 14 5 — 430 83 7 C X C X C X X X 6 6 6 430 73 *invention

(32) In table 1, the temperature of the exterior wall of the door indicates the maximum temperature measured on the exterior glass pane of the door, e.sub.1 is the spacing between substrate 1 and substrate 2, e.sub.2 is the spacing between substrate 2 and substrate 3 in a triple glazing. In the case of a quadruple glazing, e.sub.3 is the spacing between substrate 3 and substrate 4.

(33) The results reported in table 1 demonstrate the advantages of the present invention:

(34) Example 7 is representative of an oven door currently used. It comprises 4 glazings, a heat-reflecting coating being positioned on faces 1, 3 and 5 of the glazing. For an average temperature of the cavity of 430° C., an exterior temperature of 73° C. is observed.

(35) The reference example 5 is a quadruple glazing in which heat-reflecting coatings have been deposited on faces 1, 2 and 3 of the various glass substrates. In this configuration, the maximum temperature measured on the exterior face 6 of the door, in contact with the outside, is equal to 65° C. when the cavity of the oven is brought to 430° C. Such a temperature makes it possible to guarantee user safety, even when the oven is brought to a very high temperature, under pyrolysis conditions for example. The drawback of such a configuration is however linked to the use of 4 glass substrates, making the door heavy and making the manufacture thereof substantially more expensive.

(36) In example 4, the fourth substrate has been removed, the spacing e.sub.1 between the first and second substrates and the spacing e.sub.2 between the second and third substrates being kept substantially identical. A significant increase in the exterior temperature of the door is then observed.

(37) In examples 1 to 3 according to the invention, the configuration of example 4 (triple glazing configuration) has been modified, by modifying the respective spacings e.sub.1 and e.sub.2, the thickness of the door being kept constant. A significant reduction in the exterior temperature of the door is observed, down to values comparable with that of the reference example 5. A particularly advantageous configuration of the invention in which e.sub.1 is greater than e.sub.2 is illustrated by example 1.

(38) Thus, according to the invention and by means of a particular combination combining a triple glazing provided with three heat-reflecting stacks respectively on faces 1, 2 and 3 of said triple glazing and a particular spacing selected between the three glass substrates, it is possible to provide lighter oven doors that even so have all the safety guarantees for the user.

(39) Example 6 should be compared with example 7 in accordance with current practice. It can thus be observed that the removal of the fourth substrate (example 6) cannot in this case be compensated for by a different spacing between the three substrates as observed by comparison between the respective examples 5 and 1 to 3.

(40) It thus appears, in view of these two examples, that it is indeed the particular combination of the positioning of the reflective coatings and of the selection of the spacing between substrates which makes it possible to minimize the temperature of the exterior face of the door.