In many engineering fields the need is ever more sharply felt for containers which would allow holding the internal temperature within a predetermined range even in the presence of external temperature changes and electronic equipment which due to its nature dissipates large quantities of heat.

In the case of electronic equipment containers one of the bigger problems which arise during their use is linked to holding an optimal operating temperature inside them because of the difficulty of dispersing the heat generated by the equipment and by solar radiations. The useful life and reliability of the equipment is a function of the operating temperature understood both as absolute values and distribution and their hourly variations.

The problem is complicated by the fact that because of its delicate nature electronic equipment is usually housed in closed containers which protect it from the weather and from handling by unauthorized persons.

In the prior art forced ventilation systems for the removal of heat from the internal compartment of the containers have been proposed but their application has not proven capable of providing satisfactory results in addition to involving relatively high energy consumption.

Even the use of conventional conditioning systems has not proven advantageous because they have problems of reliability and power supply since they cannot be powered by batteries and accordingly if mains power fails air conditioning stops with a fast increase in internal temperature, operating and maintenance costs and noise problems.

The general purpose of the present invention is to obviate the above mentioned shortcomings by making available a container for housing heat generating equipment which would allow holding the temperature inside it within the range of optimal values for operation of the equipment contained therein with hourly gradients considerably lower than those obtainable with conventional systems and with high reliability.

Another purpose of the present invention is to make available a container which although capable of dissipating fairly high powers would have reduced overall dimensions within the limits required for ready transport thereof.

In view of these purposes it has been sought to provide in accordance with the present invention a container for housing heat generating equipment and holding in an internal compartment thereof a temperature between a preset minimum temperature and a preset maximum temperature and comprising a system for dispersal of heat from the internal compartment characterized in that said heat elimination system consists of a first air-flow dissipation device with an air/air exchanger of heat with the external environment and a second air/liquid dissipation device contained in spaces defined by pairs of mutually facing walls interconnected to form panels which constitute at least partially walls of the compartment with at least one of said walls forming the air spaces being heat conducting and arranged in thermal contact with the interior of the compartment with heat exchange means being provided between the liquid contained in the air spaces and the external environment.

In the container in accordance with the present invention is provided a dissipation system using air or liquid as the thermal carrier fluid depending on the amount of heat to be eliminated and in which the liquid substance can act as the thermal carrier or thermal accumulator depending on whether its temperature. is higher or lower than that of the external environment.

In comparison with conventional passive conditioning systems the container in accordance with the present invention is produced with materials easy to find and allows dissipation of higher powers for equal size and lower costs for equal power dissipated. In addition, given the smaller dimensions for equal power dissipated the containers are easy to transport even completely assembled with clear cost advantages.

To clarify the explanation of the innovative principles of the present invention and its advantages compared with the prior art there is described below with the aid of the annexed drawings a possible embodiment thereof by way of non-limiting example applying said principles. In the drawings: - Fig. 1 shows an elevation view along plane of cut I-I of Fig. 2 of a first embodiment of the container in accordance with the present invention, - Fig. 2 shows a view of the container of Fig. 1 along plane of cut II-II, - Fig. 3 shows a perspective view of a second embodiment of the container in accordance with the present invention, - Fig. 4 shows a diagrammatic side view of the container of Fig. 3 showing the air circulation path, - Fig. 5 shows an elevation view of a side panel containing thermal carrier liquid for removal of heat from the container of Fig. 3, and - Fig. 6 shows a view similar to Fig. 4 with a production variation of the air circulation circuit.

With reference to Figures 1 and 2 a container 10 made of heat conducting material for example steel or aluminum comprises side walls indicated generally by reference number 12 and a bottom wall 13.

In the example shown the container 10 is arranged in a buried position housed in an excavation in the ground 11.

A container provided in this manner however can also be used on the surface with possible structural and finish modifications which might be necessary. In the case of a container to be used in a buried position it should be protected against corrosion due to oxidation and any stray currents in the ground.

The walls 12, 13 are designed to be thermally in contact with the external environment (in this case the ground 11) once the container is in operating position.

Above, the container 10 is equipped with an opening 14 for access to an internal compartment 15 for containing the equipment to be protected. The container is equipped with a first cover 16, internal, for tight closing of the compartment 15 against possible water and dust infiltrations and a second cover 17, external, designed to provide adequate mechanical resistance against external loads over the container. Between the two covers 16, 17 there can also be arranged thermal insulation means consisting for example of an insulating mattress 18 to prevent overheating of the external cover 17 due to solar radiation causing undesired increases in temperature inside the compartment 15.

Advantageously the internal cover 16 can be fixed to the walls delimiting the compartment 15 in a known manner by means of bolts not shown for the sake of graphic clarity and tightness is assured by suitable means such as for example an O-ring. The external cover 17 can be the cast iron type commonly used for closing manholes and technological pits present below road level.

In accordance with the innovative principles of the present invention the container 10 comprises a system for elimination of the heat produced inside it and consisting of a first dissipation device which uses an air flow as a thermal carrier fluid'and a second device for accumulation and dissipation using as heat accumulation and transport fluid a liquid contained in the panels 22 constituting side walls of the container.

The first dissipation device is advantageously usable when the internal temperature is higher than the external temperature while the second device operates when the external temperature is higher than the internal temperature and it is not possible to dissipate the heat to the exterior. In addition the latter device acts as a thermal filter with respect to the external environment to dissipate or absorb heat depending on the negative or positive temperature differences resulting in corresponding heat flows through the walls.

As may be seen in Fig. 1 the first dissipation device consists of an external air circulation circuit 27 extending between an inlet opening 28 and an outlet opening 29 appropriately provided with respective grills 30, 31. The circuit 27 comprises a portion 32 for descent of the air towards the bottom of the container and portions 33, 34 for rising and heat exchange with the interior of the compartment 15 to generate a natural one-way circulation of the air.

Along the circuit 27 are arranged heat exchange elements 35, 36 consisting of a plurality of fins in thermal contact with the interior of the compartment 15.

Advantageously the heat exchangers 35, 36 are arranged along the circuit portions 33, 34 located opposite the cover 16 and a side wall not provided of the above mentioned panels 22 of the second dissipation device which are described in detail below. In particular the circuit portion 34 with the heat exchanger 36 can be an integral part of the movable cover 16.

The configuration of the circulation 27 is such that when the external temperature is lower than that in the compartment 15 there is set up along the circuit a natural air circulation between the inlet 30 and the outlet 31 as diagrammed in Fig. 1 by means of the arrows 37 so as to carry off the heat transmitted from the interior environment 15 to the heat exchangers 35, 36. The heat accumulation system making up an integral part of the temperature control system in the container in accordance with the present invention consists of panels 22 arranged opposite the walls of the container 10 covering them for at least 30% and preferably for at least 50% of their extent. In the embodiment shown the panels 22 cover two of the side walls 12 of the container as may be seen in Fig. 2. Depending on the specific conditioning requirements however the panels 22 can also involve other walls for example the bottom wall 13.

The panels 22 consist of a pair of mutually facing walls 23, 24 interconnected to define between them a space 25 filled with liquid having freezing temperature between a minimum and a maximum temperatures admissible within the container. The quantity and physical characteristics of the freezable liquid'are selected in each case depending on the heat dissipated by the equipment housed in the container and the climatic characteristics of the place of use.

The panels 22 can be provided in accordance with various known construction techniques based on the specific structural and economic requirements. In any case the panel 22 displays a first wall 23 turned towards the exterior of the container and arranged in thermal contact with the environment and a second wall 24 turned towards the interior and in thermal contact with the air contained in the compartment 15.

The walls of the panels 22 can comprise a plurality of fins 26 (shown only partially in Fig. 2) to increase the contact surface with the freezable liquid in the space 25.

In particular the wall 24 can advantageously be equipped with fins even towards the internal compartment 15 to improve heat exchange with the air in the container.

It is noted that the substance contained in the space 25 constitutes thermal capacity for long conservation in the compartment 15 of the optimal temperature absorbing the heat generated by the equipment contained therein when the external temperature is higher than the internal temperature and releasing it when the external temperature falls below the internal temperature and also acting as a thermal filter towards the outer environment.

Elimination of the heat fed into the thermal accumulators when the external temperature is higher than the internal temperature takes place by means of feeding it back into the internal environment when the internal temperature is higher than the external temperature and eliminated through the air circulation device or through a purposeful exchanger.

Another barrier function against reaching unsuitable temperatures for correct operation of the equipment is performed by the latent heat connected with any change of state of the freezable substance.

Operation of the thermal capacity making up part of the container in accordance with the present invention is described briefly below with reference to an embodiment with reference to a typical summer day. It is understood that the cycle described here can take place on condition that the quantity of liquid and its freezing temperature and the percentage of surface covered by panels are selected correctly, depending on the climate of the location considered and the characteristics of the ground in which the container may be housed and the actual quantity of heat generated by the equipment contained therein.

The substance contained in the space 25 solidifies progressively in the presence of low external temperatures and releases the accumulated heat in the less cold period.

At the next temperature rise the frozen substance absorbs the heat generated by the equipment and returns to the liquid state thus representing the double function of thermal filter towards the external environment and thermal accumulator for the heat dissipated by the equipment.

If the thermal accumulators are not equipped with a cooling circuit (an arrangement suited to low powers and cold climates) heat dissipation takes place both by utilizing the sensible heat of the liquid in the accumulators and by utilizing the latent heat connected with its change of state and in particular utilizing a liquid with high melting temperature in hot climates or low in cold climates. If on the other hand the thermal accumulators are equipped with a cooling circuit (for high powers and cold climates) it is advantageous to utilize only the measurable heat).

As an indication the hourly gradient of internal temperature variation in the container in accordance with the present invention can be held within a range from 0.1"C and 1.5°C.

During the night hours when the external environment becomes cooler the panels 22 release heat thereto through the contact of the container with the ground or with the surrounding air so as to reach morning with the thermal capacity again capable of absorbing the heat dissipated during the following hours.

It is clear that the thermal cycle described can be adapted to the particular performance required by appropriately selecting the physical characteristics of the substance contained in the panels. For example in the case of high external temperatures and high powers dissipated by the equipment there can be advantageously used a substance with high melting temperature near the maximum admissible temperature in the container. In this manner the latent heat absorbed during melting virtually prevents reaching of the maximum temperature. In the case of small dissipated power and low external temperature with the possibility of freezing it may be advantageous to use substances with low melting temperature so as to exert control over the temperature near the lower limit of the operating range.

Advantageously the panels 22 can have one wall connected with the heat exchange elements for example with the exchanger 36 as shown in Fig. 2. In this manner heat dissipation through the circuit 27 contributes to cooling of the thermal capacity of the panels 22.

In the embodiment shown in Figures 1 and 2 in the compartment 15 of the container is arranged a housing 19 for the equipment to be protected and which can consist for example of a signal amplifier for cables and optical fibers 20 belonging to a telecommunications network.

The housing 19, for example an equipment supporting plate, can advantageously be mounted on a structure 21 extendable upward to emerge from the opening 14 of the container so as to make the equipment easily accessible from the outside for maintenance and replacement.

In Figures 3 to 6 is shown a second form of embodiment of a container with a heat elimination system in accordance with the present invention. This second embodiment permits receiving devices with above-ground installation.

For the sake of convenience elements corresponding or assimilable with those of the above embodiment are indicated in Figures 3, 4, 5 and 6 by the same numbers plus 100.

With reference to Fig. 3 a container 110 with side wall 112 and bottom wall 113 is made in the form of a conventional shelter with an access door 116 and an internal compartment 115 for housing equipment not shown for the sake of clarity.

In Fig. 3 the container is shown with walls and roof partially cut away to display the interior better.

The container 110 is provided with a first device for internal heat dissipation by means of circulation of an air flow between the compartment 115 and a finned heat exchanger 136 arranged opposite the rear wall of the shelter and equipped with a first plurality of passages for the air to be cooled and coming from the interior of the compartment 115 and a second plurality of passages alternating with the former for an opposite flow of cooling air coming from the exterior.

As may be seen in Figures 3 and 4 the exchanger 136 comprises for each of the passages traveled by the air to be cooled an upper portion 140 for inlet of the flow coming from the internal compartment 115 and a heat exchange portion 141 along which the air descends due to the cooling effect undergone and a lower portion 142 for outlet of the cooled air in the compartment 115.

The exchanger 136 also comprises for each passage traveled by the cooling air a lower portion 143 for inlet of the flow coming from the exterior and a heat exchange portion 144 along which the cooling air absorbs the heat yielded by the internal air and returning upward and an upper portion 145 for exhaust to the exterior.

In Fig. 4 the path 143, 144, 145 for return upward of the cooling air is shown only partially to make visible the back path 140, 141,142 for descent of the air to be cooled.

A duct 146 for conveyance of the air towards the portion 140 for inlet into the exchanger 136 is arranged in the upper part of the compartment 115 delimited below by a false ceiling 147 which virtually extends partly or entirely over the length and width of the compartment. In the false ceiling 147 advantageously in the zone furthermost from the exchanger 136 is provided an opening 148 for passage of the air from the compartment 115 to the duct 146.

In Fig. 4 is shown the operating diagram of the above mentioned air-circulation dissipation device when there are provided appropriate means for providing forced circulation of the internal air and consisting for example of blowers 160 shown diagrammatically in Fig. 3. After emerging from the exchanger 136 the air in the compartment 115 indicated by the arrows 149 is conveyed advantageously by means of an appropriately shaped deflector 161 towards the upper part of the compartment where is concentrated the greater part of the heat generated by the equipment to remove it. The air thus heated then enters the duct 146 through the opening 148 and is conveyed towards the portion 140 for inlet into the exchanger 136. Here it strikes the walls of the exchanger in thermal contact with the cooling air (indicated by means of the arrows 150) cooling and falling by gravity along the portion 141 where heat continues to be yielded to the air coming from the exterior. Lastly the air thus cooled leaves the exchanger through the lower portion 142 to again enter the compartment 115.

Fig. 6 shows a container 110 in a version advantageously suited to use in climates where forced air circulation is not necessary. In this case the air 149 emerges below the exchanger 136 and returns upward by natural circulation through the compartment 115 and removes the heat generated by the equipment in addition to the heat which might filter through the walls of the container equipped with less thermal insulation, for example in the zone of the door 116. The heated air then penetrates into the upper duct 146 as in the case described above.

In the zone nearest the exchanger 136 the duct 146 is advantageously formed like a siphon with a first portion 162 for descent of the air and a second portion 163 for return upward to the inlet 140 of the exchanger. In this manner reverse circulation of the air is prevented when the external temperature is higher than the internal temperature. The heat exchange circulation in the exchanger 136 is naturally identical with the above case.

The cooling air 150 which enters into the exchanger through the lower portion 143 returns upward by natural circulation along the intermediate portion 144 thanks to the heating caused by the heat yielded from the flow 149 and then emerges through the upper portion 145. On the roof of the container above the exchanger 136 there can be provided a deflector 151 designed to created forced exhaust of the air 150 from the exchanger to improve the efficiency of the exchanger in the presence of a breeze outside the container. Advantageously the deflector 151 also functions as a protective screen against the sun's rays in the exchanger zone.

The container 110 also comprises a second dissipation device consisting of a pair of closed circuits for circulation of a thermal carrier liquid between respective panels 122 arranged opposite the side walls 112 of the container and corresponding heat exchangers 152 arranged on the roof thereof.

As shown diagrammatically in Fig. 3 the panels 122 consist of a pair of walls 123, 124 mutually facing and interconnected to define between them a space 125 filled with the above mentioned heat carrying liquid.

Advantageously the panels 122 are covered externally with a layer of heat insulating material 153.

In the embodiment shown each exchanger 152 consists of finned portions (externally and advantageously also internally) of duct 154 which extends parallel between respective upper ends 155 and lower 156 for hydraulic connection with the interior of the panel 122 to provide respectively an outlet and an inlet for the liquid in the panel. This configuration is quite visible in Fig. 5. In the sections adjacent to the panels 122 the ducts 154 are equipped with appropriate heat insulation.

As an alternative the exchangers 152 can be equipped with walls with corrugated surface to improve internal and external heat exchange.

Advantageously in the panel 122 are arranged finnings 157 appropriately shaped and directed in such a manner as to aid return upward of the liquid without turbulence from the inlet 156 to the outlet 155 as shown diagrammatically in Fig. 5 by means of the arrows 158. The finnings 157 also have the function of increasing the contact surface between the liquid and the conductive wall 124.

Proceeding from below upward the passage cross section at the sides of the baffles 157 decreases on the inlet side and increases on the outlet side of the fluid to make circulation more uniform in the horizontal sections of the exchanger.

The thermal carrier liquid circulation circuits are also provided with appropriate expansion vessels 159 advantageously arranged on the roof of the container as shown in Figures 3 and 5.

There is now described briefly the operation of the system of heat elimination from the container 110 illustrated in Figures 3 to 6. When the external temperature is lower than the temperature in the compartment 115 the air-circulation dissipation device operates. The air in the compartment is heated by the effect of the heat generated by the equipment and rises towards the opening 148 to enter into the upper duct 146 delimited by the false ceiling 147 and travels along it in natural or forced circulation until it reaches the air/air exchanger with opposed flow 136. Here the internal air is cooled by the air 150 coming from the exterior and descends along the exchanger to return into the compartment 115 and repeat the cycle.

When the amount of heat removed from the air/air exchanger is less than that produced by the equipment in addition to any heat which might penetrate into the compartment 115 through insufficiently insulated walls heat dissipation is put into effect by the liquid circulation device. This liquid is an aqueous solution of suitable composition and absorbs heat from the compartment 115 through the inner walls 124 of the panels 122.

If the external temperature is lower than that of the liquid there is set up a natural circulation of the liquid through the liquid/air exchangers 152. This circulation causes the colder fluid entering the panel 122 through the lower inlets 156 to push the fluid already present in the space 125 upward conveyed by the deflectors 157. This fluid rises to strike the entire wall 124 of the panel to remove heat from the interior of the container and finally emerges from the panel through the outlets 155. Along the finned portions of the exchangers 152 the external air cools the thermal carrier liquid which then returns downward along the ducts 154 to the passages 156 for inlet into the panel 122 to repeat the heat dissipation cycle.

When the external temperature is higher than that of the liquid there is no circulation through the exchangers 152.

In the panel 122 there are formed convective flows by the effect of the heating of the wall 124 with a resulting exchange of the liquid layer in contact therewith. In this case the panels 122 act simply as thermal accumulators until the external temperature falls below that of the fluid, after which the exchangers 152 can resume operation.

Advantageously the fluid present in the circuit can be selected with density and viscosity varying with the temperature in such a manner as to modulate the quantity of heat removed depending on its temperature. In particular the characteristics of the fluid can be such as to completely stop circulation below 4-5"C so as to prevent excessive cooling of the compartment 115 in case of very low external temperatures.

It is clear from the foregoing description that for conditioning of the interior environment of the container in accordance with the present invention there is zero energy consumption. There may be energy consumption although minimal if it is desired to arrange a small blower in the container to mix the air and thus aid heat exchange through the walls or provide forced circulation of the air flow along the ducts.

Naturally the above description of an embodiment applying the innovative principles of the present invention is given by way of example of said innovative principles and is not to be taken as a limitation of the protective scope of the patent claimed.

In particular the number and arrangement of the panels 22, 122 and of the heat exchangers can be different from that described.

The thermal accumulation panels of the embodiment of Fig. 1 can also be equipped with a circuit for circulation of the fluid with liquid/air exchangers as in the embodiment of Fig. 3. These exchangers can be arranged for example in the air outlet duct after the exchange surfaces 34. The container of Fig. 1 can thus dissipate a larger quantity of heat. As an alternative or in addition the portion of wall 24 bordering on the air duct can have exchange finnings between the fluid in the panels and the air in the duct.

In addition the surface of the exchangers can be provided with all the characteristics of form and chemical-physical treatment known to those skilled in the art to improve heat exchange with special reference to configuration of the external exchanger fins.