EP4172533A1

EP4172533A1 - Lighting system with air-supported structure and improved forced cooling

Info

Publication number: EP4172533A1
Application number: EP21787028.6A
Authority: EP
Inventors: Guido Medici; Walter MAURI
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-06-25
Filing date: 2021-08-06
Publication date: 2023-05-03
Also published as: WO2021260672A1

Abstract

The invention concerns a lighting system comprising a bearing structure (2) in turn comprising an air-supported envelope (21), means (11) for blowing an inflating air flow (4) into said envelope (21) maintaining such a pressure as to guarantee its rigidity and stability, at least one lighting module (3) inside said envelope (21). Said lighting module (3) in turn comprises a heat sink (33) for the dissipation of heat and lighting bodies (31) mounted on said at least one heat sink (33). The system comprises two thermal switches set at different temperature values.

Description

LIGHTING SYSTEM WITH AIR-SUPPORTED STRUCTURE AND IMPROVED

FORCED COOLING DESCRIPTION

This patent relates to the lighting sector and in particular to air-supported light towers for field lighting. It involves a new light-weight lighting system where the lighting bodies - preferably but not necessarily LED lamps - are cooled by conveniently exploiting part of the air pumped into the structure to create the necessary internal pressure.

SUBJECT OF THE INVENTION The subject of the invention is the system for optimizing the cooling of the LED lighting bodies installed on light towers the bearing structure of which is made of fabric or flexible material supported by means of the continuous blowing of air into the structure itself.

In the new lighting system covered by this patent, the cooling system uses a forced air flow, which simultaneously performs two functions: a first function related to the inflation and maintenance of the minimum pressurization of the lighting system body and a second function related to the cooling of the lighting bodies.

One advantage of the present patent is to simplify the construction of LED lighting systems and - furthermore - to reduce the weight and dimensions of the cooling heat sinks of the lighting bodies.

The new lighting system can be modular, and is comprised of a substantially tubular shaped envelope made of flexible material, such as fabric for example, which can easily be folded up to minimize its size for transport for use in emergency situations or interventions in difficult locations. PRIOR ART

Tower lighting systems known in the prior art use bearing structures made of flexible materials which are inflated and kept pressurized and in the proper position by means of the continuous blowing of air inside the structures themselves.

These systems have been the subject of various patents by the same applicant, the primary ones are indicated below:

European patent no. 1062458, having as its subject a temporary and/or emergency lighting system with an inflatable bearing structure;

Italian utility patent no. 102015000055989, having as its subject an inflatable bearing structure with one or more light sources;

European patent no. 2577155, having as its subject a lighting system with an inflatable bearing structure and safety devices;

International patent application no. WO2019/243948 concerning a modular lighting system with forced cooling. LED (Light Emitting Diode) lighting bodies are also known in the prior art and have a lifespan which varies considerably depending on the luminous flux, the working current, and the operating temperature.

In particular, the construction of LED lighting systems must maintain the operating temperature within a certain maximum threshold, above which the operation of the LED is impaired or its average lifespan shortens exponentially.

LED lighting bodies must therefore be installed with appropriate heat dissipation devices. In general, aluminum finned heat sinks are used, whose weight and dimensions are defined according to the nominal installed power and proportioned to the latter. In the case of high power LEDs, devices with large dissipation surfaces are required which can have significant weight and size.

In these cases the cooling of the heat sink is often facilitated by directing a forced air flow in the direction of the dissipation fins with suitably positioned fans. Various types of ventilation devices are therefore added to the heat sink. The problem of the size and weight of the cooling devices is particularly relevant in the case of light towers with air-inflated bearing structures the LED lighting bodies of which are positioned at the top, that is, at the top of the bearing structures themselves. In this situation, the internal pressure of the load-bearing structure must be higher in relation to the weight of the lighting body it has to support. In addition, since the bearing structure is supported with air continuously blown into it, in the event of a power interruption - and in the absence of an uninterruptible power backup system - the structure collapses quite fast. It is clear that - in this specific case - the minimal weight of the lighting body is a key safety factor. It follows that in these specific LED lighting applications, the systems must be suitably cooled by heat sinks and forced air flows.

It also follows that, for the same reason, using additional ventilation systems placed on the lighting body would increase the weight at the top of the bearing structure.

The patent document RU 194196 U1 describes a lighting system with an air-supported structure having a plate installed therein.

Said plate in turn comprises some openings at the level of which there are bent parts. The lighting bodies and the cooling heat sinks are mounted on said bent parts, wherein a cooling air flow passes through the empty spaces between the fins of the heat sinks. A covering plate is mounted on said heat sinks in such a way as to convey the cooling air flow between the fins of the heat sink, preventing it from moving upwards. Said configuration has the purpose of optimizing the heat exchange between the air flow and the heat sink, and thus the cooling of the lighting bodies.

However, the air that flows out of the heat sinks is heated and remains in proximity to the air-supported structure before being discharged towards the outside, thus partially reducing the heat exchange effectiveness.

The patent document WO 2016/003322 A1 concerns a lighting system with an air- supported structure comprising, at the top of the air-supported structure, a lighting body directly mounted on a heat sink which in turn is mounted on a supporting plate. The air flow circulates around the heat sink and goes out into the atmosphere, but there is no indication on how the air flow circulates inside the heat sink.

The patent document EP 3 450 835 A1 concerns a lighting system with an air- supported structure inside which there is a lighting device in turn comprising lighting bodies mounted on a box-shaped structure having a heat sink with fins where the cooling air flow circulates. Once having flown out of the heat sink, the heated air does not flow directly outside but circulates inside the air-supported structure.

The patent document DE 10 2016 014 803 A1 concerns a lighting system with an air- supported structure comprising an air vent positioned on the lower side of the air- supported structure.

SUMMARY OF THE INVENTION

The invention of the present patent overcomes and resolves the aforementioned problems by exploiting the air blown to support the bearing structure, to optimize the cooling of the heat sinks and therefore the LEDs without affecting the inflation speed of the bearing structure and without resulting in pressure losses that may compromise its static stability.

This result is obtained with the precise positioning of heat sinks and appropriate ventilation holes.

Other characteristic aspects and advantages of the new lighting system are:

- the distinctness of the light diffusion system;

- the compactable nature of the invention for its transport and storage.

To reduce the glare of a light source by using a light diffusion surface made of plastic or other rigid materials, it is known that the size of this surface must be proportionate to the intensity of the source itself.

It follows that the greater the power supplied, the greater the diffusion surface needed. The present lighting system provides for large and variable light diffusion surfaces made of flexible fabric, wherein the individual components of the lighting module can be easily removed, folded or otherwise used in order to reduce the invention to the minimum dimensions for storage and transport.

DESCRIPTION OF THE INVENTION

The main parts of the new lighting system comprise a bearing structure suited to support at least one lighting module, a support base for said bearing structure, and means for blowing air inside the bearing structure.

The bearing structure is preferably constituted by a cylindrical and/or conical envelope, for example, made of fabric or flexible plastic or non-plastic materials, having an open end and connected to said base to allow the insufflation of air, and an opposite end equipped with suitable outlet holes for part of the insufflated air.

At least one lighting module or light source is mounted inside said bearing structure. At the lower end of the bearing structure there is one or more of said air blowing means or fans which take air from the environment and blow it inside the envelope.

Said at least one lighting module is placed inside the envelope constituting the bearing structure, wherein said lighting module in turn comprises at least one LED lighting body and at least one heat sink, configured as described and claimed below.

The new system is very simple and can be put into operation quickly.

All that is required is to remove the system from its container and place it on the ground.

The fans continuously introduce pressurized air into the bearing structure inflating it and providing the necessary stability-rigidity.

Consequently, the inflation of the bearing structure positions said at least one lighting module at the height desired by the operator.

Said air flow blown in by said fans is also used to provide ventilation for the heat sinks of the lighting module, thus contributing to its cooling. Thanks to this solution, the cooling efficiency of the heat sinks is maximized and consequently the size and weight of the heat sinks themselves can be significantly reduced.

The attached drawings show, by way of a non-limiting example, a practical embodiment of the invention.

Figure 1 shows the lighting system (100) in the operating configuration. It comprises a base (1), an air-supported bearing structure (2), and a lighting module (3).

Said bearing structure (2) comprises a diffuser envelope (21), for example made of a fabric or other flexible material having a generally tubular shape.

Means (11) for blowing air (4) taken from the environment into said diffuser envelope (21) are housed inside said base (1).

Figure 2 illustrates, by way of example and only schematically, a sectional detail of the lighting module (3) with LED lighting bodies (31), for example oriented downwards.

Figure 2a shows a plan view of the detail of Figure 2.

Figures 3a and 3b illustrate, by way of a non-limiting example, a sectional detail and a top view only of the lighting module (3) with LED lighting bodies (31), for example oriented so as to project the light horizontally.

Figure 3c shows an alternative embodiment of Figure 3a, where the heat sink (33) is spaced from the upper support (32), and wherein a distribution duct (343) conveys the air flow from inside the ventilation ducts (34) outwards through one or more holes (321) made on said support (32).

Figure 4 illustrates, by way of a non-limiting example, a detail of several lighting modules (3) with LED lighting bodies (31) in plan view, for example oriented so as to diffuse the light radially.

Regardless of their position, each lighting module (3) comprises: at least one support (32) suitably made of heat conductive material, having a substantially flat shape, for example circular or rectangular or polygonal in general; at least one ventilation through hole (321) is made on said support (32); at least one heat sink (33) suitably made of a heat conductive material and in turn comprising at least one heat dissipation plate (331), of any shape, for example square or circular, and a plurality of dissipation fins (332), and wherein said heat sink (33) is mounted on a face of said support (32); in the embodiment in Figure 2, said heat sink (33) preferably has a smaller size than said support (32) to enable, as will be better described below, the passage of the air flow (4) between said dissipation fins (332) and the outlet of the air flow through said at least one ventilation hole of the support (32); one or more high-power LED lighting bodies (31), directly or indirectly constrained to said dissipation plate (331).

The entire system consisting of: 1) said dissipation plate (331);

2) said dissipation fins (322) of said heat sink (33);

3) and the overlying support (32) creates ventilation ducts (34) through which said ambient temperature air (4) taken from the environment flows, being blown by said ventilation devices (11). DYNAMICS OF PRESSURE AND AIR FLOW RATE

As noted, the present invention exploits the air flow (4) introduced into the air- supported bearing structure (2) to optimize the cooling of the lighting unit (3) installed at the top of said bearing structure (2).

Figure 5 illustrates the general principle.

The air flow (4) taken from the environment is blown into the bearing structure (2) by the turbine (11). The fast flow of air (4) inside the tube allows it to inflate, exerting uniform pressure (40) on the fabric surface (21). A part of the air flow (41) exceeding the flow rate necessary for creating and maintaining the pressure (40) enters the ventilation ducts (34) of the heat sink (33) and is released (42) from the holes (321) positioned at the top of the bearing structure (2) and communicating directly with the outside of said envelope (21).

CONCEPT AND DYNAMICS OF THE AIR FLOW AVAILABLE FOR COOLING The forced path of the air flow as conceived and illustrated in the present invention significantly increases the efficiency of the heat sink and enables its size and consequently its weight to be reduced. It was found that it is possible to reduce the thickness and the radiant surface of the heat dissipation system by up to 50-60% compared to the heat sinks commonly used with said LEDs.

Figures 5a, 5b and 5c illustrate, by way of a non-limiting example, the forced path of the air such that a significant optimization of the cooling of the LEDs is obtained even in the presence of a small heat sink positioned horizontally.

In this embodiment, said support (32) is positioned flush with the dissipation fins (332) of the heat sink (33) and is provided with one or more ventilation holes (321) at the level of the ventilation ducts (34), in such a way that an air flow passes through each ventilation duct (34) continuously and linearly without generating turbulence.

Figure 5a illustrates the path of the air flow (41) along the longitudinal section of the ventilation duct (34).

Figure 5b illustrates the same path of the air flow (41) along the cross section of the ventilation duct (34).

Figure 5c shows the horizontal plan view of the same path of the air flow (41) along the ventilation duct (34) on a circular heat sink (33).

Figure 5d shows the horizontal plan view of the same path of the air flow (41) along the ventilation duct (34) on a rectangular heat sink (33).

In the aforementioned figures, the flow of fresh air (4) coming from the external environment, the main task of which is to inflate the air-supported bearing structure (2) and create the necessary internal pressure, is forced to enter and flow along the ventilation ducts (34).

Said air flow (41) flowing inside said ventilation ducts (34) comes in contact with and cools all the internal surfaces of said ventilation duct (34), which consist of: said dissipation fins (332); said dissipation plate (331); said support (32).

The air flow (41) is released at a higher temperature (42) through at least one ventilation hole (321) of the support (32), which communicates directly with the outside of said envelope (21).

In Figures 5a, 5b, 5c and 5d, other holes (321) are present on said support (32) at the level of said ventilation ducts (34); said support (32) is constituted by a flat circular plate having a diameter substantially equal to the diameter of the envelope (21) of the bearing structure (2) and is positioned at the top (22) of said bearing structure (2).

In Figure 5d the heat sink (33) has a rectangular shape, for example, or is in any case smaller than said support (32), so that the gap on the side is large enough for the passage of said air flow (41) from inside the bearing structure (2) to the ventilation ducts (34).

As already explained, one or more holes (321) are made on said support (32), for example - but not necessarily and/or exclusively - aligned along the diameter of the support (32) itself, each at the level of one of said ducts (34). One or more heat sinks (33) can also be positioned vertically. In the embodiment shown in Figures 3a and 3b, said support (32) is not positioned flush with the heat dissipation fins (332) of the heat sinks (32) but is positioned orthogonally to the heat sink (33), above the ducts (34). The heat sink (33) is positioned vertically and oriented so that said ventilation ducts (34) created between the heat dissipation fins (332) are also positioned vertically, offering a lower opening (341) for the entry of the air flow and an upper opening (342) for the outlet of the air flow. On the support (32) there are one or more ventilation holes (321) through which the air is released from the bearing structure.

The embodiment in Figure 4 shows the possible positioning of multiple heat sinks (33) arranged vertically inside the bearing structure (2) and joined together so as to form a not necessarily closed geometrical shape in plan view, for example a triangle.

In the embodiment shown in Figure 4, said support (32) may comprise one or more central holes (32 G) for enhanced ventilation, in order to obtain better cooling if necessary. If, as an alternative to said one or more central holes (32 G), said support (32) comprises holes (321) at the level of each of the ventilation ducts (34) of the heat sinks (33), it is also possible to provide for the application of a further element (33 G) placed so that it adheres to the fins (332) to create the ventilation ducts (34).

The innovative concept of all the embodiments shown in the figures is the same. It lies in conveying the air flow (4) generated by said ventilation devices (11) between the fins (332) of the one or more heat sinks (33) to contribute to the cooling effect, and then releasing the heated air flow through at least one hole (321) made on said support (32), wherein said hole (321) connects the inside of said ventilation ducts (34) with the outside of the bearing structure (2), that is, the air-supported envelope (21) of the bearing structure (2).

Said envelope (21) of the bearing structure (2) comprises for this purpose at least one opening or hole (211) for the release of the hot air flow.

Said support (32) and said heat sink (33) are for example wholly or partially made of aluminum.

Said lighting system may also comprise at least one upper protective cap for the electrical system and the components of the lighting modules (3), not shown in the figures.

VARYING THE VENTILATION AIR SPEED WHILE KEEPING THE HEAT SINK UNCHANGED

At present, to use high power LEDs it is necessary to consider that they generate a lot of heat, which must be conveniently dissipated. For this purpose, in the known art the size of the heat sink is increased, for example the number or the thickness of the fins is increased. Alternatively, it is possible to increase the speed of the air flow which passes between the heat sink fins, thus increasing also the flow rate of the system. SOLUTION 1

According to the first solution, it is possible to improve the heat exchange and increase the performance of the heat sink (33) by adopting the following solutions:

* increasing the air flow by acting on the speed of the fan of said air blowing means (11);

* increasing the diameter of said holes (321) for letting out the hot air. Therefore, said air blowing means (11) are provided with at least one fan (110) and at least one speed variator for said at least one fan (110), with speed selector, wherein the selector is set at predefined, discrete and discontinuous values.

Furthermore, the size of said holes (321) is changed according to the air flow, in order to maintain the pressure inside said envelope (21) constant at predefined values.

For example, during the design and assembly stage it is thus possible to establish that the fan can be set at certain speed values in order to obtain the air flow rate which is necessary to ensure that the installed lighting bodies (31) are cooled with no need to modify the heat sink (33).

The size of the vent holes (321) is determined according to the above.

This method thus makes it possible to increase the heat exchange without actually changing the size of the heat sink. SOLUTION 2

According to the second solution, the system comprises a speed selector for said at least one fan (110). During the inflation of the envelope (21) said selector is in the position corresponding to the maximum air flow rate.

Once the envelope (21) has been inflated, that is, once a pre-established pressure value has been reached inside the envelope (21), said speed selector is set at a lower value, so that the speed of said at least one fan (110) decreases, reducing also the energy consumption and the noise emissions of the system accordingly.

Said speed value is the value which is sufficient to maintain the optimal pressure inside the envelope (21). S FETY OF THE SYSTEM

It is known that the optimal operating temperature of the LEDs commonly used in this field is generally included between 70 and 90 °C. In any case, the operating temperature should not exceed 90 °C. For this reason, the use of thermal switches is known, wherein these thermal switches interrupt the power supply to the LEDs when the latter accidentally exceed said limit temperature value.

According to the present solution, the system comprises at least two of said thermal switches, each set at different temperature thresholds.

In particular:

* a first thermal switch is connected to a first group of LEDs and is set at a first temperature threshold, or risk threshold, for example equal to 80 °C,

* a second thermal switch is connected at least to the remaining LEDs and is set at a second temperature threshold, or limit threshold, for example equal to 90 °C, which must never be exceeded.

When the temperature of said first group of LEDs reaches said risk threshold, which is lower than the limit threshold, said first thermal switch turns off the LEDs of said first group, which will cool down, while the ventilation process continues and cools down all the LEDs, even those still working.

Said LEDs of said first group are turned on again once their temperature has lowered to a safety value, for example equal to 60 °C.

Consequently, the lighting effect is partially reduced but it is not completely interrupted.

If the temperature of said LEDs should accidentally reach the limit threshold, that is, for example, 90 °C, said second thermal switch intervenes and interrupts the power supply to all of the LEDs completely.

The solution described above can be applied also to lighting bodies different from LEDs.

Therefore, with reference to the preceding description and the attached drawings, the following claims are made.

Claims

1. Lighting system comprising at least one bearing structure (2) in turn comprising at least one air-supported envelope (21), means (11) for blowing an inflating air flow (4) into said at least one envelope (21), maintaining such a pressure as to guarantee its stiffness and stability, at least one lighting module (3) contained inside said at least one envelope (21), wherein said lighting module (3) in turn comprises at least one heat sink (33) for heat dissipation and one or more lighting bodies (31) mounted on said at least one heat sink (33), characterized in that said at least one heat sink (33) comprises at least one heat dissipation plate (331) having said one or more lighting bodies (31) mounted thereon, and a plurality of heat dissipation fins (332), and wherein between two adjacent heat dissipation fins (332) at least one ventilation duct (34) is defined for the circulation of said air flow (4) generated by said air blowing means (11), and wherein said at least one lighting module (3) comprises at least one support (32) made from a conductive material and integral with said at least one heat sink (33), mounted on the top of said envelope (21), and wherein said support (32) is provided with at least one ventilation through hole (321) for the outlet of said air flow circulating inside said ducts (34), and wherein said at least one hole (321) communicates directly with the outside of said envelope (21).

2. Lighting system, according to claim 1, characterized in that said lighting bodies (31) are LED bulbs.

3. Lighting system according to claim 1 or 2, characterized in that said at least one lighting module (3) comprises: said at least one support (32) made from a heat conductive material, said at least one heat sink (33) made from a heat conductive material and mounted on one face of said support (32) in such a way that said heat dissipation fins (332) of the heat sink (33) are oriented towards said support (32); said one or more lighting bodies (31), directly or indirectly constrained to said heat dissipation plate (331).

4. Lighting system according to claim 1 or 3, characterized in that said support (32) is a circular flat plate having a diameter that is substantially equal to the diameter of the envelope (21) of the bearing structure (2), and arranged horizontally on the top (22) of said bearing structure (2), and wherein, on the other hand, said heat sink (33) has, for example, a rectangular shape, or in any case smaller than said plate (32), so that at the side, between said heat sink (33) and said envelope (21) some space is left for the introduction of said air flow into said ducts (34).

5. Lighting system according to claim 1 or 2, characterized in that said lighting module (3) is positioned vertically inside said envelope (21), in such a way that also said ducts (34) are positioned vertically, offering a lower opening (341) for the introduction of the air flow and an upper opening (342) for the outlet of the air flow.

6. Lighting system according to claims 1, 2, 5, characterized in that it comprises one or more of said heat sinks (33) configured and/or mounted in such a way as to form, in plan view, a circular or polygonal closed shape, and wherein said lighting module (3) comprises said upper support (32) made from a heat conductive material (32) provided with at least one through hole (321) for the outlet of the hot air flow.

7. Lighting system, according to the preceding claims, characterized in that said envelope (21) of the bearing structure (2) comprises at least one opening or hole (211) for the release of the hot air flow.

8. Lighting system, according to the preceding claims, characterized in that said support (32) and said heat sink (33) are entirely or partially made of aluminum.

9. Lighting system, according to the preceding claims, characterized in that said air blowing means (11) comprise at least one fan (110) and at least one speed variator for said at least one fan (110) with a speed selector.

10. Lighting system, according to the preceding claims, characterized in that it comprises at least two thermal switches connected to one or more of said lighting bodies (31), and wherein a first thermal switch is set at a first temperature threshold, or risk threshold, and a second thermal switch is set at a second temperature threshold, or safety threshold, which is higher than said risk threshold.

11. Lighting system according to claim 10, characterized in that said first thermal switch is connected to a first group of said lighting bodies (31), in such a way that when the temperature of one or more of said lighting bodies (31) of said first group reaches said risk threshold said first thermal switch turns off only said lighting bodies (31) belonging to said first group.

12. Lighting system according to claim 11, characterized in that said second thermal switch is connected at least to said lighting bodies (31) not belonging to said first group, in such a way that when the temperature of one or more of said lighting bodies (31) reaches said second safety threshold said second thermal switch interrupts the power supply to all of said lighting bodies.

13. Operating method of a lighting system according to claim 9, characterized in that it comprises the following steps:

- variation of the air flow generated by said at least one fan (110) obtained through the variation of the speed of said at least one fan (110); installation of said support (32), wherein said at least one hole (321) for the outlet of the hot air towards the outside is especially sized as a function of the air speed, so that higher speeds of the air are associated with bigger sizes of said at least one hole (321), in such a way as to maintain the pressure inside said at least one envelope (21) at a predefined value.

14. Operating method of a lighting system according to claim 9, characterized in that it comprises the following steps: - inflating said envelope (21) until reaching a pre-established pressure value inside the envelope (21), wherein said selector is in the position corresponding to the maximum air flow rate; once the inflation step has been completed and said pressure value has been reached, setting said speed selector at a pre-established lower value to maintain an optimal pressure value inside said envelope (21), in such a way that the speed of said at least one fan (110) decreases and consequently reduces also the energy consumption and noise emissions of the system.