[0001] The present invention relates to a domestic freezer of the type comprising a cavity
in which, at different levels, there are arranged flat members for the products to
be frozen, said members essentially being constituted by evaporator coil portions
interconnected in series. A domestic freezer is taken to mean here either an upright
freezer or a refrigerator comprising same, for example refrigerators with two or more
compartments in which at least one compartment is at a temperature substantially below
0°C, either of the superimposed type ("fridge/freezer" refrigerators) or of the side-by-side
type.
[0002] In known freezers, the shelves for the deep-frozen and/or frozen products which are
kept at low temperatures for extended periods are constituted by the above-stated
"grids",
i.e. horizontal evaporator portions defined by a looped course of the evaporator tubing
to which there are attached (for example by welding or brazing) a plurality of metal
rods or wires. These latter cooperate with the evaporator tube to increase the heat-exchange
surface thereof, to stiffen the structure thereof and, in some cases, act as a support
for the foodstuffs when the latter are not contained in suitable sliding boxes or
baskets arranged between the grids. Such an embodiment offers the advantage of ensuring
good air circulation (and thus good heat exchange) between the grids, but suffers
from non-uniform temperatures within the chamber primarily due to the arrangement
of the upper grid, which is located close to the top of the chamber.
[0003] The object of the present invention is to provide a freezer of the type defined above
at the beginning of the description, which freezer offers advantages both in terms
of energy saving and in terms of reducing product costs.
[0004] Said object and other advantages are achieved by a freezer as defined in the attached
claims.
[0005] Using a metal plate which accommodates the tubing of the highest portion of the evaporator
(
i.
e. that which is closest to the top of the freezer cavity) makes it possible to achieve
more efficient cooling of the upper part of the freezer compartment, which is typically
hotter than the other zones. Thanks to said more efficient cooling, the temperature
gradient within the cavity is reduced and thus so too is the energy wastage associated
with an uneven temperature distribution within the compartment. Another advantage
of the freezer according to the invention is the elimination of the separate holding
tank (or "canister") which is conventionally fitted beside the grid stack for the
purpose of collecting the refrigerant fluid in the liquid phase prior to input into
the compressor, so as to avoiding damaging the compressor valves. This is possible
by incorporating said tank into the metal plate acting as the upper grid. Providing
the plate instead of a conventional "grid" allows the user to make better use of the
small space defined by the upper grid and of the top of the cavity (currently used
to contain eutectic packs). Since, according to the invention, the metal bars or wires
of the grid are eliminated, so too are cleaning problems and the user is able to make
better use of this space, albeit small.
[0006] Further advantages and features of a freezer according to the invention will be obvious
from the following detailed description, which is provided merely by way of non-limiting
example, with reference to the attached drawings, in which:
- Figure 1 is a perspective view of a grid stack used in a freezer of conventional design;
- Figure 2 is a view similar to Figure 1 and shows a grid stack of a freezer according
to the invention;
- Figure 3 is a plan view from beneath (with reference to its in-service configuration)
of a plate used in the freezer of Figure 2 in its state prior to folding into an L-shape
of a rear portion thereof along a line indicated P;
- Figure 4 is a plan view (according to the arrow IV) of the metal plate shown in the
grid stack of Figure 2; and
- Figure 5 is a view according to arrow V of the metal plate shown in the grid stack
of Figure 2.
With reference to the drawings, 10 denotes the overall evaporator to be used in an
upright freezer or in a household electrical appliance equipped with a compartment
(not shown) for maintaining a temperature substantially below 0°C and with a vertical
access door. In Figure 1, the evaporator 10 of conventional type is defined by a plurality
of horizontal evaporator portions or grids 10a, 10b and 10c (three in number in the
solution described) constituted by the evaporator tube T in a planar looped arrangement
to which are attached metal bars or wires F parallel one to the other. Figure 1 also
shows the capillary tube C originating from the condenser (not shown), which goes
into the upper grid 10a and, the holding tank M for the refrigerant liquid arranged
downstream from the lower grid 10c and upstream from the return tube T' to the compressor.
[0007] In the solution according to the invention, shown in Figures 2-5, the evaporator
comprises an upper metal plate 12 exhibiting a horizontal portion 12a (in the in-service
configuration of the evaporator inside a freezer chamber) and a portion folded into
an L shape 12b which, in the installed configuration of the evaporator 10, is suitable
to fit close to a rear vertical wall of the freezer chamber. Both the portions 12a
and 12b of the metal plate 12 provide tubing K accommodated in association with the
faces respectively facing downwards and towards the vertical wall of the chamber (not
shown). In particular, the tubing K may be obtained for example by means of one of
the techniques used in the production of roll-bond or Z-bond type evaporators, in
which two superposed metal sheets are deformed under pressure in predetermined zones
to form the coil or tubing for passage of the refrigerant fluid.
[0008] With particular reference to Figure 3, 14 is the inlet connection of the capillary
tube C into the vertical portion 12b of the plate 12. The refrigerant fluid expands
in the tubing K provided in association with the horizontal portion 12a of the plate
12 in the direction shown by the arrows. On leaving the horizontal portion 12a of
the plate 12 at the outlet A, the refrigerant fluid continues to expand in portions
10b and 10c beneath, which are entirely similar to those used in the conventional
solution described in Figure 1. On leaving the lower portion 10c of the evaporator,
the return tube is connected at B to the vertical portion 12b of the plate 12, in
which is accommodated an elongate holding tank 16 obtained by the same technique used
to obtain the tubing K. The tank 16 does not communicate with the connection 14 and
with the portion of the evaporator downstream from the connection, but is connected
at 18 to a return tube 20 to the compressor. A portion of the capillary tube is wound
around the tube 20 before the input connection 14, for the purpose of improving heat
exchange between the gaseous refrigerant fluid leaving the tank 16 and the refrigerant
fluid being input into the plate 12 of the evaporator 10.
[0009] It is obvious how the flat, smooth surface of the upper side of the portion 12a of
the plate 12 readily lends itself to easy cleaning within the space constraints allowed
by the small distance between the plate 12 and the ceiling of the freezer chamber.
Moreover, inserting or removing small items, for example ice-cube trays, is much easier
in comparison with conventional metal wire grids.
[0010] Although the description refers to an upper plate in which the tubing is obtained
by means of plastic deformation of one of two facing metal sheets integral one with
the other, the results of the present invention are also understood to extend to solutions
in which the coil is welded onto a(n under)side of a metal sheet or to the solution
in which the plate is formed from two facing sheets with opposing half-channels forming
the coil.
1. A domestic freezer of the type comprising a cavity in which, at various levels, there
are arranged flat members (10a, 10b, 10c) defined by portions of coil evaporator in
the form of grids, characterised in that at least one of said supports (10a) comprises a metal plate (12), on one of the faces
of which there is accommodated or arranged the associated evaporator portion.
2. A freezer according to claim 1, characterised in that the evaporator portion is substantially accommodated in association with a lower
face of the plate (12).
3. A freezer according to claim 1 or 2, characterised in that said plate (12) is arranged close to an upper wall of the freezer cavity.
4. A freezer according to claim 1 or 3, characterised in that a holding tank (16) to collect the refrigerant fluid upstream from the compressor
is integral with the plate (12).
5. A freezer according to claim 4, characterised in that the plate comprises a vertical portion (12b) folded into an L shape and is arranged
close to a vertical wall at the back of the cavity, said holding tank (16) being accommodated
in association with said vertical portion (12b).
6. A freezer according to claim 5, characterised in that the connection between the capillary of the refrigerant circuit and the evaporator
is provided in association with said vertical portion (12b) of the plate (12).
7. A freezer according to claim 5 or 6, characterised in that the connection of the return tube (B) of the lower portion (10c) of the evaporator
(10) is provided in association with said holding tank (16).
8. A freezer according to any one of the preceding claims, characterised in that the evaporator portion of the metal plate (12) is manufactured by means of plastic
deformation of a coil-shaped zone of said plate.