The present invention generally relates to controlled-temperature packages and in particular to an isothermal container for passive refrigeration.

Background of the invention

Among controlled-temperature packages isothermal containers for passive refrigeration are widely known and used. These containers employ cooling masses arranged inside them so as to allow to preserve products during their transportation.

An isothermal container for passive refrigeration is basically a box made of an expanded resin, typically expanded polystyrene, manufactured by way of a molding process. Inside the box a cavity suitable to receive and store products is formed. An isothermal container also comprises a lid that seals its cavity.

An isothermal container is generally designed and dimensioned according to the duration and the climatic conditions foreseen for transportation, as well as according to a temperature range required for a specific type of product, and depending on the size and amount of the products to be stored and transported.

In order to carry out passive refrigeration, a cooling mass, generally consisting of dry ice or equivalent heat exchange means, is housed in an isothermal container. The heat exchange means are for example packaged in the form of units or cartridges covered by a microporous plastic film in turn covered by cardboard elements.

The heat exchange means that form the cooling mass may be arranged in the cavity intended to receive the products, for example between the products to be stored and transported and the peripheral walls of the cavity, or in separate compartments formed in the container or separated from its cavity and arranged e.g. underneath the lid. The latter configuration of isothermal containers is preferred, because it allows to avoid a direct contact between the cooling mass and the products, and also because, given a cooling mass, it allows to adjust heat exchange by suitably dimensioning the thickness of the wall that separates the compartment housing the cooling mass from the container cavity. More particularly, an isothermal container for passive refrigeration that is provided with a lid compartment allows, for example, preservation of goods at a temperature between 0°C and 4°C by employing a cooling mass in the form of dry ice at a temperature of -80°C.

The possibility to adjust heat exchange with a same cooling mass by acting on the thickness of the bottom wall that separates the lid compartment from the container cavity advantageously allows a dimensional standardization of isothermal containers.

However, it is known that expanded polystyrene, and more generally the plastic resins used to manufacture isothermal containers, are materials having a poor mechanical strength, more particularly these materials are poorly resistant to pull, shear and bend stresses. Hence, once a cooling mass required for a specific set of products to be transported has been calculated, this limits the design of the lid compartment as far as the minimum thickness of its bottom wall is concerned.

Moreover, still due to the poor mechanical strength, it is generally not possible to form through openings in this separation wall in order to promote heat exchange, because these openings would further weaken the structure intended to support the cooling mass.

Summary of the invention

The technical problem underlying and solved by the invention is therefore to provide an isothermal container having a lid compartment that is free from such drawbacks. Said object is achieved with an isothermal container with a lid compartment whose main features are specified in the first claim, while other features are specified in the remaining claims.

An idea of solution underlying the invention is to modify the lid compartment by forming a through opening in its bottom wall and by closing said through opening with a plate made of a material having a mechanical strength higher than the mechanical strength of the material, for example polystyrene foam, of which the lid compartment is made. More particularly the plate has a higher bend and shear strength, which are the stresses that are typically generated on a plate supported along the edges and intended to support a load. Thanks to this combination of features, it is possible to provide the bottom wall of the lid compartment with a thicknesses so thin as to promote, and more generally adjust, heat exchange to and from the cavity of an isothermal container, while having no limits as far as mechanical strength is concerned. Depending on the desired thermal exchange, it is in fact possible to choose the most suitable thickness, shape and material for the plate.

Suitable materials for the manufacturing of the plate closing the through opening of the lid compartment are for example expanded polyurethane, expanded polypropylene, cellular polyethylene or aluminum.

Thanks to the use of materials that are mechanically stronger than expanded polystyrene, it is also possible to form one or more through openings in the plate. For a given plate thickness this allows to increase convective heat exchange to and from the container cavity. Hence, given a cavity volume, a designer has more freedom to design an isothermal container, which offers the advantage of a standardization level higher than what is practically achievable with prior art isothermal containers.

Further advantages and features of the isothermal container according to the present invention will be clear to those skilled in the art from the following detailed and non-limiting description of embodiments thereof. Brief description of the drawings

The invention will be described with reference to the following drawings in which:

• Figure 1 is a perspective, longitudinal section view showing an isothermal container according to an embodiment of the present invention;

· Figure 2 is an exploded perspective, longitudinal section view of the isothermal container of figure 1 ;

• Figure 3 is an exploded perspective, longitudinal section view showing an alternative embodiment of the isothermal container of figure 1;

• Figure 4 is a perspective view showing a lid of the isothermal container of figure 3; · Figure 5 is an exploded perspective, longitudinal section view showing an alternative embodiment of the container according to the invention. Description of preferred embodiments

Referring to figure 1, an isothermal container according to the present invention is generally indicated with reference numeral 100.

The isothermal container 100 comprises a container cavity 110 and a lid 120 configured to seal the container cavity 110.

The container cavity 110 and the lid 120 of the isothermal container 100 are designed and dimensioned according to the duration and climatic conditions foreseen for transportation, as well as according to a temperature range required for a particular type of product, and depending on the size and amount of products to be stored and transported.

The isothermal container 100 further comprises a lid compartment 130 intended to contain a cooling mass (not shown) for example consisting of a plurality of dry ice units or cartridges.

In the embodiment shown in figure 1, the lid compartment 130 has for example the same size of the container cavity 110 seen from above and is fitted on the top of it thus sealing it. The container lid 120 instead seals the lid compartment 130.

According to the present invention, the lid compartment 130 comprises a through opening 131 formed in a bottom wall 132 thereof, for example made during its molding process, and also a plate 140 that is arranged on the peripheral edges of the through opening 131 thereby closing it.

In the illustrated embodiment, the through opening 131 has a shape and a size substantially corresponding to the shape and size of the bottom wall 132, but it will be appreciated that this is not a limiting feature of the invention and that the through opening 131 might have a different shape and a lower size compared to the bottom wall 132.

The plate 140 is made of a material such as e.g. expanded polyurethane, expanded polypropylene, cellular polyethylene or aluminum, which have good thermal insulation properties and a mechanical strength that is generally higher than that of expanded polystyrene in terms of pull, shear and bend resistance, thus allowing to make strong bottom walls even when they have a small thickness, for example in the order of few millimeters.

More generally, the plate 140 is made of a material that is mechanically more resistant to pull, shear and bend forces than the material of which the lid compartment 130 is made.

Given a cooling mass, it is thus possible to adjust heat exchange through the plate

140 that separates the lid compartment 130 from the container cavity 110 in a more effective manner compared to prior art isothermal containers. Depending on the desired insulating design, it is possible to choose the most suitable thickness, shape and material for the plate 140.

In order to increase the loading capacity given a certain material, it is advantageously possible to form reinforcing ribs on the plate 140, or to provide the plate 140 with a honeycomb structure.

The plate 140 may advantageously be blocked on the bottom wall 132 of the lid compartment 130 in order to make the assembly of the two components more stable.

To this purpose, as particularly shown in figure 2, the isothermal container 100 comprises locking means 150 arranged between the lid 120 and the plate 140. The locking means 150 can for example be in the form of blocks arranged along two opposite sides of the through opening 131 formed in the lid compartment 130.

The height of the locking means 150 substantially corresponds to the distance between the lid 120 and the plate 140 resting on the bottom wall 132 of the lid compartment 130 so that by fitting the lid 120 into the lid container 130, the locking means 150, e.g. the blocks shown in figure 2, are enclosed without play between these two components, thereby preventing the plate 140 from being raised or, more generally, moved relative to the through opening 131.

Alternatively to the blocks, the locking means 150 can be configured as an annular element arranged along the periphery of the opening 131 formed in the lid compartment 130. As in the case of the blocks, the height of the annular element substantially corresponds to the distance between the lid 120 and the plate 140 resting on the bottom wall 132 of the lid compartment 130, thereby preventing the plate 140 from being moved relative to the opening 131.

The blocks, the annular element, or any equivalent locking means 150 may advantageously be integrated into the lid 120.

Figures 3 and 4 show, for example, an annular element 150 integrated in the lid

120.

Now referring to figure 4, according to an alternative embodiment of the invention, the plate 140 may advantageously comprise one or more through openings 141 which, for a given thickness, allow to promote heat exchange between the cooling mass housed in the lid compartment 130 and the products stored in the container cavity 110. The through-openings 141 can be made thanks to the mechanical properties of the material used to make the plate 140, which, as explained above, are higher than the mechanical properties of the material of which the lid compartment 130 is made.

The invention has been described with reference to preferred embodiments thereof. It will be appreciated that there may be further embodiments relating to the same inventive concept, as defined by the scope of protection of the claims set forth below.