REFRIGERATING APPARATUSES

The present invention refers to an improved insulating glass door, in particular for refrigerating apparatuses.

As known, the art proposes the use of doors or the like comprising glass surfaces for closing the refrigerating apparatuses, mainly for commercial use, in order to allow a user to see their contents. The use of such glass surfaces is obviously preferable than the open solutions, also for energy saving reasons.

In particular, the characteristics of glass surfaces are linked to use conditions of the apparatus, namely mainly type (ex. horizontal, vertical, etc.), internal temperature, external temperature and external humidity.

In the sector of apparatuses with operating temperature equal to -18 °C, namely negative temperature, the glass door is normally composed of a triple glass, whose global thickness ranges in general between 24 and 36 mm, composed of an electrically heated external glass, of a channel with dry air fluid and aluminium raceway with molecular sieve, of an intermediate glass, of un channel with dry air fluid and aluminium raceway with molecular sieve and of an internal glass. Generally, the glass thickness ranges between 3 and 4 mm, and the channels between 6 and 12 mm. Each one of the six glass surfaces that is encountered moving from outside towards inside the apparatus is generally designated with the term "face" and is conventionally progressively numbered starting from 1.

In general, the external heated glass is composed of a tempered glass, whose thickness is 4 mm, with a surface metal deposit that is placed on the internal face of such glass, namely in face 2: heating occurs through voltage (normally between 12 V and mains supply, for example 230V 50Hz) applied to two points (or two equipotential bars, called "bus bars") of the surface with metallic deposit, that, behaving like a resistance, dissipates the electric supply power into heat. The normally used value is 100 /m ² .

The surface metallic deposit, suitable laid onto the glass surface in order to insulate it from the rest (for example from the metallic raceway) , is usually of the pyrolytic type, obtained through a deposit formed as a thin film of metal alloys vaporised at high temperatures on the glass surface during its production. This solution ensures, together with the resistance normally housed in the glass door frame (metallic or plastic) , the absence of external condensate under all external thermal and hygrometric conditions.

In order to remove the energy consumption of such solution, that is caused not only by the direct consumption but also by the greater (indirect) consumption of the apparatus caused by the re-entries of heat towards inside the apparatus, it is common to use always triple glasses but with two metallic deposits, called low- emissive, in face 2 and in face 3, 4 or 5.

In order to obtain better performances, a type of low emissive devices are used of the magnetronic type, obtained by depositing, as a thin film, metal alloys vaporised at high temperatures in a vacuum environment on the glass surface during its production that, with respect to the pyrolytic one, is characterised by a lower emission coefficient. This aspect, reducing heat transmission by radiation between the faces, improves the glass insulation coefficient.

For completing, in order to oppose the transmission that occurs on board the glass, that normally is configured as the most critical point, the aluminium raceway is replaced by its version with a thermally insulating material (plastic) , and dry air gas is replaced with argon, that, being a heavier gas, reduces heat convection between glass faces .

This arrangement, however being practiced by optimising- its specific components, has anyway the limit of offering a valid solution till external thermal hygrometric conditions that have not their dew point lower than the external temperature of glass-frame .

Therefore, the current scenario provides for a glass door with resistance always on (possibly being thermostated or manual actuations, with low insulation) or a glass door free from resistance that, in case of unfavourable thermal hygrometric conditions, produces surface condensate.

From the point of view of energy consumption, namely in case of request for limiting the energy consumption, it must be taken into account that the tests are performed under certain thermal hygrometric conditions (for example 25°C 60% RH and 30°C 55% RH) and that, under such conditions, the glass door must not have condensate.

Therefore, if the door without supply is suitable for consumptions and for the absence of condensate under test conditions, the supplied door, that without supply does not reach the absence of condensate under test conditions, would ensure the absence of condensate under any external condition .

Therefore, object of the present invention is solving the above prior art problems by providing an improved insulating glass door, in particular for refrigerating apparatuses, that, without supply, is able to show absence of external condensate in traditional test classes (25°C 60% RH and 30°C 55% RH) , thereby allowing to perform the energy consumption tests without specific consumptions .

The above and other objects and advantages of the invention, as will result from the following description, are obtained with an improved insulating glass door, in particular for refrigerating apparatuses, as claimed in claim 1. Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.

It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) can be made to what is described without departing from the scope of the invention as appears from the enclosed claims.

The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which:

Figure 1 shows a front view of a preferred embodiment of the improved insulating glass door, in particular for refrigerating apparatuses, according to the present invention;

Figure 2 shows a sectional view along line A-A of the insulating door of Figure 1;

Figure 3 shows a sectional view along line B-B of the insulating door of Figure 1; and

Figure 4 shows an enlarged view of the part of the insulating door contained in circle F of Figure 2. With reference to the Figures, it is possible to note that the improved insulating glass door 1 according to the present invention, in particular for refrigerating apparatuses, is composed of:

- at least one external glass 3 equipped with at least one low-emission heatable pyrolytic deposit layer, for example through one of the two equipotential bus bars 5, in face 2;

- at least one first channel 7 containing fluid, preferably argon, and a plastic raceway with molecular sieve;

- at least one intermediate glass 9 equipped with at least one low-emission magnetronic deposit layer in face 3 or 4;

- at least one second channel 11 containing fluid, preferably argon, and a plastic raceway with molecular sieve;

- at least one internal glass 13;

- at least one frame 15 with possible resistance in parallel with the resistance of the deposit in face 1.

Possibly, it can be provided that also the internal glass 13 is coated with a deposit in face 5.

Obviously, heating of the external glass 3 can be controlled through a suitable manual actuator or automatically with a specific control, should thermal hygrometric conditions so require. For such purpose, it must be remembered that the heatable metallic deposit is a low emissive pyrolytic deposit .

Advantageously, therefore, the insulating door 1 according to the present invention solves the prior art problems by replacing the known completely passive solution with external glass equipped with magnetronic deposit with an external glass 3 equipped with a pyrloytic deposit that can be electrically supplied, and by inserting the resistance into the frame 15 of the door itself: this implies a lower degree of insulation, anyway much higher that the one that can be obtained with the unsupplxed heated glass of the prior art.

Experimentally, the Applicant has verified that, in case of an insulating door equipped with a frame with a 30-mm glass, technically the following are obtained (U in W/Km2) :

- unsupplied heated glass according to the prior art : U = 1.6;

- completely passive glass according to the prior art : U = 1.1; - insulating door 1 according to the present invention: U = 1.2.