WO2017075721A1 - Method for cooling an led lighting means arranged on a heat sink - Google Patents

Abstract

The invention relates to a method for cooling an LED lighting means (2) arranged on a heatsink (1). In this context, the heat sink (1), with the LED lighting means (2) arranged thereon, is arranged in a hermetically sealed housing (5) which is filled with a fluid (6), in particular air (6) and has a first partial region (5a) in which the housing walls are composed essentially of a transparent material and serve as an exit face for the light generated by the LED lighting means (2). At least one circulation flow (8, 9, 10) composed of the fluid (6) located in the housing (5) is generated within the housing (5) by means of a feed device (3), particular a fan (3), such that this circulation flow (8, 9, 10) is guided along cooling faces of the heat sink (1) and housing wall faces, and during the circulation it progressively absorbs heat from the heatsink (1) and outputs it to the housing walls. The method according to the invention makes it possible to make available LED lighting arrangements with hermetically sealed housings, which LED lighting arrangements permit relatively low barrier layer temperatures of the LED despite dispensing with external lamp heat sinks, even with relatively high LED power levels.

Description

 A method of cooling an LED illuminant disposed on a heat sink

TECHNICAL AREA

 The invention relates to a method for cooling an LED illuminant disposed on a heat sink and an LED lighting arrangement for carrying out the method according to the preambles of the independent claims.

 In particular, the invention relates to the cooling of LED semiconductors in high-performance LED lighting systems, such as today in general LED indoor and outdoor lighting, street lighting, workplace lighting, medical lighting, technical lighting, etc. be used.

 STATE OF THE ART

Every high-performance LED lighting system - with typical electrical input powers in the one to three-digit watt range - requires a cooling system at a low temperature level for trouble-free and long-lasting operation. This cooling is realized now by the prior art, typically by direct Passisvkühlung so that the LED array (Geo ^¬ metric arrangement of several to hundreds of LED semiconductor chips) planar (on a thermally conductive Kühlsub ^¬ strat usually aluminum core-board or ceramic Substrate). This cooling substrate is then installed from the inside in a heat-conducting lamp housing, which is externally provided with cooling fins. The heat loss to the environment by heat radiation and heat the air, which ported by convection the waste heat ABTRANS ^¬. The optical outlet opening of the lamp housing is closed with a transparent planar or refractive material (eg glass, PMMA or polycarbonate, etc.). The outer cooling fins tend to pollution - with which a not inconsiderable maintenance effort (especially in the area of exterior lighting or dusty environment) arises. Nonplanar luminous surface geometries (eg point and line emitters for the generation of directable light and for the reduction of glare) can hardly be realized with this construction.

 Other, passively cooled designs place the heat sink with the LED in a hermetically sealed lamp housing. By heating the heat sink occurs in a temperature difference range of about 40 ... 60 ° C, a free convection flow, which passes along the cooler walls of the lamp housing, which gives off heat and this in turn emits on the outside to the environment by convection. Non-planar field geometries are possible, but the performance of such systems is limited to the low two-digit watt range (typically 15 ... 30W).

The typical junction temperatures of the LEDs in these designs are 100 ... 130 ° C. Unfortunately, such high operating temperatures not only severely shorten their life, but also massively reduce the light output of the LED.

Still other constructions use an ak ^¬ tive fluid cooling, liquid cooling systems are not common because of cost reasons. By Fan di ^¬ rectly with outside air have forced cooled LED Beleuchtungssys ^¬ tems Although he reported ^¬ be very efficient and compact and also allow the realization of nonplanar ren light field geometries with high luminance; aller- recently at the price that the power supplied to the system Conversely ^¬ ambient air, the active cooling system (fan blades Kühlrip ^¬ pen, housing parts, filters, etc.) contaminated quickly where ^¬ by the maintenance costs are even higher than the traditional passive cooling systems , In outdoor areas all attempts to realize economically operating open Active cooling systems are rich yet we ^¬ gen rain, snow, dust, pollen, soot, insects, etc. failed. Typical cleaning intervals range from a few months to half a year, which is unacceptable for commercial applications. In comparison: Conventional street lamps are cleaned at intervals of 1 to 5 years, depending on the place of installation.

PRESENTATION OF THE INVENTION

 It is therefore the object to provide a technical solution that does not have the aforementioned disadvantages of the prior art or at least partially avoids. In particular, the object is to provide a cooling method and an LED lighting arrangement, which are able, with multiple LED power (currently 50 ... 00) without external lamp heat sinks the junction temperatures of the LED to at most 50 ... 80 ° C. to keep.

 This object is solved by the subject matters of the independent claims.

 Accordingly, a first aspect of the invention relates to a method of cooling a LED illuminant disposed on a heat sink, e.g. a single LED chip or an LED array (geometric arrangement of several to hundreds of LED semiconductor chips).

Here, the heat sink with the fact reasonable arranged LED lamps in a fluid-tight before ^¬ zugterweise hermetically closed and with a fluid (gaseous or liquid), preferably air-filled casing disposed, which has a light exit region (demanding contemporary first portion) Open has, in which the housing walls substantially, ie completely or at least for the most part, from a transparent material, preferably glass, are formed and serve as an exit surface for the light generated by the LED bulb. Within this housing, one or more forced convective circulating flows of the fluid in the housing are created, for which a preferably electrically operated conveyor is used. By "circulating flow" is meant here fluiströmungen in which the flow forms a cycle.

 Depending on whether a gaseous or liquid fluid is used, this conveyor may for example be a fan, a blower, a propeller or a pump. In the case of several circulating flows, a common conveying device can be used for several or all circulating flows or even several conveying devices.

Thereby the circulating flows, given ^¬ if produced in such a way with the aid of flow directing devices such as spoilers, air ducts, air tubes, auxiliary fan and partition walls that they flow along the cooling surfaces of the heat sink and then along housing wall surfaces and thereby accommodate continued while heat from the heat sink and leave the housing walls.

 The method according to the invention makes it possible to provide LED lighting arrangements with closed housings which, despite the omission of external lamp heatsinks, allow relatively low junction temperatures of the LED even with large LED powers.

Hence non-planar geometries Leuchtfeldgeo ^¬ (eg including coupling to low-glare reflector Opti ^¬ ken) are possible, and at much higher performance and at the same time lower LED junction temperatures than existing LED lighting systems. The closed by the environment fluid volume also creates no pollution. The lifetime of today's special fans with ceramic, magnetic or fluid dynamic bearings is within the expected LED service life. Lack of external heat sink and the cleaning intervals are no higher than in the previous smooth-walled Leuch tengehäusen ^¬. It is also possible by the inventive method now, the optically transparent, but so far barely used or hardly used light exit covers (eg coverslips in floodlight or headlight housings, all-round glazing in lanterns or glass balls in ball lights) for the heat dissipation use and include in the system design.

 In a preferred embodiment of the method, a housing is used, which has a non-light exit area (second part of the claim) in which the housing walls do not serve as the exit surface for the light generated by the LED illuminant and preferably entirely or in the intended manner are formed for the most part of a non-transparent material, with advantage of a metallic material, eg made of aluminum, copper, brass or stainless steel. In this case, the circulating flow or the circulatory flows are generated in such a way that they are guided along housing wall surfaces of the light exit region of the housing and / or along housing wall surfaces of the non-light exit region of the housing. Depending on the lamp design and cooling concept, one or the other of these alternatives or the combination of the same may be particularly favorable.

 It is further preferred that several

Circulation flows are generated, in particular exactly two circulating flows, in such a way that a first circulating flow along cooling surfaces of the heat sink and then along housing wall surfaces of the light exit region of the housing is performed and a second circulation ^¬ flow along cooling surfaces of the heat sink and then along Housing wall surfaces of the non-light exit region of the housing is guided. In this way, both the housing wall surfaces of the light output occurs ^¬ range and the housing wall surfaces of the non ^¬ light exit sbereichs the housing can be used intensively for heat dissipation. This is done with advantage with a common conveyor for the circulating flows. As a result, the system engineering effort can be kept low.

 In a first preferred variant of the method in which a plurality of circulating flows are generated, the first circulating flow is generated such that it orbits substantially in a vertical plane. The second circulating flow is generated to circulate substantially in a vertical or horizontal plane. This variant of the method is particularly suitable for lamp geometries which have a pot-shaped light exit area, at the top of which a pot-shaped or ceiling-shaped non-light exit area adjoins, such as e.g. classic hanging lamps or garden lanterns.

 In another preferred variant of the method in which a plurality of recirculating flows are generated, the recirculating flows are generated such that they circulate substantially in a vertical plane. This variant of the method is particularly suitable for flat, large-area lamp geometries, such as e.g. flat ceiling or tunnel luminaires.

In yet another preferred Execute ^¬ ungsvariante of the method in which a plurality of circulation generated currents v / ground, the first circulation flow is generated such that it flows first along housing ^¬ wall surfaces of the light exit portion of the housing and then flows into the second circulation flow, with which it then flows together along Gehäusewand- surfaces of the non-light exit region of the housing before the total current formed from the first and second circulating flow flows back to the heat sink.

Is thereby, which is preferred, at the point at which the first circulating flow in the second Circulation flow occurs through the flowing second circulating flow creates a pressure gradient, eg by means of an ej ektorartigen training of flow-leading components (flow pump), through which the first circulating flow is sucked into the second circulating flow, so there is a particularly intense first circulating flow with a correspondingly good heat exchange the housing wall surfaces. This also makes it possible, even in relatively large and deep pot-shaped housing geometries to achieve a stable circulation flow along the housing wall surfaces.

In yet another preferred embodiment of the method in which a plurality of recirculating flows are generated, the first and second recirculating flows, after being led separately from housing wall surfaces of the light exit region of the housing and the non-light exit region of the housing, are combined and then as total current again led to the heat sink. The separate along the circulating flows along the respective housing wall surfaces has the advantage that optimum heat transfer to the housing wall surfaces is possible because the heat of the two circulating ^{¬ flows is} not cooled by the cooler, which would be accompanied by a deterioration of their heat exchange efficiency ,

In a preferred design variant of the method, generated in 'which a plurality of circulating flows v / ground, which resulted as the total flow to the heat sink ^¬ the one, the allocation of the run of the conveyor to the cooling body the total flow within the cooling body, in such a way that the Fluid streams, which form the first and second circulating flow, leave the heat sink at different locations, in particular in opposite directions. As a result, it is possible to dispense with additional splitting ^devices . Advantageously, the partial fluid streams, which form the first and the second circulating flow, are deflected in the heat sink, in each case preferably by 90 °. This results in an improved heat transfer from the heat sink to the fluid streams.

 In another preferred embodiment variant of the method, in which a plurality of circulating flows are generated, which are conducted as a total flow to the cooling body, the distribution of the total flow guided by the conveying device to the cooling body takes place downstream of the cooling body. Thus, the total current heated by the cooling body is divided into the partial fluid streams which form the first and second circulating flows only after the heat sink.

 In a further preferred embodiment of the method according to the invention, the cooling body is arranged at a distance from the housing walls. This results in the advantage that there is a great freedom of design with respect to the placement of the heat sink in the housing.

In another preferred embodiment of the method according to the invention, the cooling body is arranged in contact with a housing wall, such that a transfer of heat from the cooling body to the housing wall can take place by means of heat conduction. This results in the advantage that part of the heat of the heat sink can already be dissipated by heat conduction to the housing wall and only the remaining residual heat has to be removed by forced convection by means of one or more circulating flows. For example, it is provided for classic hanging lamps or street lamps or garden lanterns, which have a pot-shaped light exit area at the top of which a pot-shaped or ceiling-shaped non-light exit area adjoins, to arrange the cooling body in heat-conducting contact with housing wall surfaces of the non-light exit area and inside of the light exit region to produce a claimed circulation flow, which flows along the housing wall surfaces of this area and thereby absorbs added heat from the heat sink to these housing walls.

 Further, it is preferable to regulate the delivery rate of the conveyor or optionally the conveyors depending on the ambient temperature and thereby adapt the delivery rate to the momentarily required heat transfer performance, resulting in power savings and at the same time the wear of the drives is reduced.

 A second aspect of the invention relates to an LED lighting arrangement (LED lighting system) for carrying out the method according to the first aspect of the invention. This comprises a LED illuminant arranged on a heat sink, e.g. a single LED chip or an LED array (geometric arrangement of several to hundreds of LED semiconductor chips), and at least one preferably electrically operated conveyor for generating a fluid flow for cooling the heat sink. The heat sink with the LED lamp arranged thereon and the conveyor are arranged within a flui-tight, preferably hermetically sealed housing which is filled with a fluid (gaseous or liquid), preferably air.

Depending on whether a gaseous or liquid fluid is used, the conveyor may be at ^¬ play, a fan, a fan, a propeller or a pump.

The housing has a light exit area (demanding first partial area), in which the housing walls are essentially formed of a transparent material, preferably glass, and serve in intended operation as an exit area for the light generated by the LED illuminant. The heat sink and the conveyor are, if appropriate using additional Strömungsleiteinrichtungen such as baffles, air ^¬ channels, air ducts, auxiliary fans and partitions, designed and arranged in the housing that in the normal operation of the LED lighting arrangement with activated conveyor at least one of the Conveyor produced forced convective recirculation flow (fluid flows in which the flow forms a fluid circuit) results from the fluid in the housing, which flows along cooling surfaces of the Kühlkör ^¬ per and then along housing wall surfaces while continuously receiving heat from the heat sink and the housing walls emits. This results in the advantages and possibilities already presented under the first aspect of the invention.

In a preferred embodiment, the housing also has a non-light exit area (demanding second subarea), in which the housing walls do not serve as outlet surface for the light generated by the LED illuminant during normal operation and preferably entirely or for the largest part of one -transparen th material are formed, with advantage of a metallic material, such as aluminum, copper, brass or stainless steel. In this case, the LED lighting arrangement is designed in this way, or in other words, the housing, the Kühlkör ^¬ per, the conveyor and possibly orhandenen additional Strömungsleiteinrichtungen are designed such that during normal operation with activated conveyor, the at least one circulation ^¬ flow along Housing wall surfaces of Lichtaus ^¬ passage area of the housing and / or along housing ^¬ wall surfaces of Nicht1ichtaustrittsbereichs of the housing flows. Depending on the design and cooling concept of the LED lighting one or the other of these alternatives or the combination thereof may be particularly preferred.

 It is further preferred that the LED lighting arrangement is designed such that during normal operation with activated conveyor several circulating flows result, in particular exactly two circulating flows, of which a first circulating flow first along cooling surfaces of the heat sink and then along housing wall surfaces the light exit region of the housing flows and a second circulating flow flows first along cooling surfaces of the heat sink and then along housing wall surfaces of the non-light exit region of the housing. In this way, both the housing wall surfaces of the light exit region and the housing wall surfaces of the non-leakage exit region of the housing can be used particularly intensively for dissipating heat.

 Advantageously, the LED lighting arrangement on a common conveyor for all circulating currents. As a result, the plant engineering effort can be kept low 'are.

In a first preferred variant of the LED lighting arrangement, in which several circulation flows result during normal operation when the conveyor is activated, the lighting arrangement is designed such that the first circulating flow essentially circulates in a vertical plane and second circulating flow essentially in a vertical plane or a horizontal plane revolves. This variant is particularly suitable for inventive LED lighting arrangements, which have a pot-shaped Lichtaus ^¬ treading on the top of a pot- or ceiling-shaped NichtIicht exit area connects, as is the case with classic hanging lamps or garden lanterns. In a second preferred variant of the LED lighting arrangement in which several circulating flows result during normal operation when the conveyor is activated, the lighting arrangement is designed in such a way that all circulating flows each circulate substantially in a horizontal plane. This variant is particularly suitable for LED lighting arrangements according to the invention which have flat, large-area housing geometries, such as flat ceiling or tunnel luminaires.

 In a further preferred embodiment of the LED illumination arrangement, in which several circulation flows occur during normal operation when the conveyor is activated, the lighting arrangement is designed such that the first circulating flow, after having flowed along housing wall surfaces of the light exit area of the housing, enters the housing second circulating flow flows in and then flows together with this then along housing wall surfaces of the non-light exit region of the housing before the total current formed from the first and second circulating flow flows back to the heat sink.

Is, as is preferred, formed, the illumination assembly such that at the point at which the first circulatory flow flowing into the second circulation flow, a pressure drop is generated by the flowing second circulation flow, for example (with ^¬ means of a ej ektorartigen formation of fluid-carrying components Flow pump), via which the first circulating flow m is sucked into the second circulating flow, so there is a particularly intense first circulating ^¬ flow with a correspondingly good heat exchange on the housing wall surfaces. This makes it possible to achieve a stable circulation flow along the housing wall surfaces even in relatively large and deep cup-shaped Gehäu ^¬ segeometrien. In yet another preferred embodiment variant of the LED lighting arrangement in which there are several circulating flows during normal operation when the conveyor is activated, the lighting arrangement is designed such that the first and the second circulating flow, separated from each other along housing wall surfaces of the light exit sbereichs of the housing or the non-light exit region of the housing have flowed together and then flow as a total current back to the heat sink. The separate flowing along the circulating flows along the respective housing wall surfaces has the advantage that an optimal heat transfer to the housing wall surfaces is possible because the warmer of the two circulating flows is not cooled by the cooler, which wü with a deterioration of their heat exchange efficiency wü.

In a preferred embodiment variant of the LED lighting arrangement in which there are several circulating flows during normal operation when the conveyor is activated and in which the circulating flows as Gesamtström flow back to the heat sink, the lighting arrangement is designed such that s the distribution of the heat sink guided total current within the heat sink is done in such a manner, the form s the partial fluid flows soft, the first and the second circulatory flow, the heat sink to un ^¬ terschiedlichen locations, in particular in opposite directions leave. As a result, can be dispensed with additional Teilteilungseinriebtungen.

 Advantageously, the fluid streams which form the first and the second circulating flow are deflected in the heat sink, in each case preferably by 90 °. This results in an improved heat transfer from the heat sink to the fluid flows.

In another preferred Ausführungsvari ^¬ ante the LED lighting arrangement, in which in In accordance with the operation according to the invention, when the conveying device is activated, there are several circulating flows and in which the circulating flows flow as total current back to the heat sink, the lighting arrangement is designed such that the distribution of the total flow takes place downstream of the cooling body. Thus, the total current heated by the heat sink is only divided after the heat sink into the partial fluid streams which form the first and the second circulating flow.

 In yet another preferred embodiment of the LED lighting arrangement according to the invention, the heat sink is arranged at a distance from the housing walls. This results in the advantage that there is a great freedom of design with respect to the placement of the heat sink in the housing.

In another preferred embodiment of the LED lighting arrangement according to the invention, the heat sink is arranged in contact with a housing wall, such that a transfer of heat from the heat sink to the housing wall can take place by means of heat conduction. This results in the advantage that a portion of the heat of the heat sink can be delivered by heat conduction to the Gehäusewarid and only the remaining heat must be removed by forced convection convective by means of one or more circulating flows. For example, it is provided for classic hanging lamps or garden lanterns, which adjoins a cup-shaped Liehtaustrittsbereich on iron on the top of a pot- or ceiling-shaped non-light exit area to arrange the cooling body in heat-conducting contact with housing wall surfaces of the non-light exit region and within the light exit region to produce a claimed circulation flow , which flows along housing wall surfaces of this area and absorbs heat from these housings by the heat sink. In yet another preferred embodiment, the LED lighting arrangement comprises a reflector for reflecting and / or bundling the light generated by the LED illuminant. During normal operation, the reflector serves as a flow-guiding device for the at least one circulating flow and / or as a cooling body for the at least one LED illuminant.

In yet another preferred embodiment of the LED lighting assembly, its housing is filled with a fluid other than air, preferably with hydrogen, helium, fluorohydrocarbon, nitrogen, carbon dioxide or sulfur hexafluoride. For example, when filling the housing with helium instead of air at the same volume flow around five times more heat can be transported or the fan power is reduced at the same heat transfer performance even _. to the factor 1/5 ³ (= 0.008).

 In yet another preferred embodiment of the LED lighting assembly, the fluid in the housing is a gaseous fluid that is under positive pressure. As a result, the heat transportability of the fluid can be increased.

 It is possible, e.g. also a combination of pressure increase and a fluid other than air, e.g. Helium. Also, chemically inert liquids (e.g., fluorochloro-hydrocarbons) having high heat capacity are provided as a fluid.

In yet another preferred execute, ungsform includes the LED lighting assembly disposed in the housing in an area which flows through the bestimmungsgemäs ^¬ sen operation with activated conveyor from the fluid or flows around, means for retaining particles of dirt and / or for preventing condensation such as fine filters, electrostatic precipitators, zeolites and / or adsorbents, in particular silica gel. In yet another preferred embodiment, the LED lighting arrangement comprises thermostatic and / or solar radiation-responsive safety or power saving devices which prevent overheating of the LED light source by means of a reduction of the supply energy or by switching off if too high LED temperatures and / or or direct sunlight is detected on the housing.

 Furthermore, it is preferred that the LED illumination arrangement has devices which regulate the delivery rate of the delivery devices as a function of the ambient temperature and thereby adapt the delivery rate to the currently required heat transfer performance, thereby resulting in power savings and at the same time reducing the wear of the drives ,

BRIEF DESCRIPTION OF THE DRAWINGS

 Further preferred embodiments of the invention will become apparent from the dependent claims and from the following description with reference to FIGS. Showing:

 1 shows the functional principle of a first LED illumination arrangement according to the invention with the housing shape of a classical lantern;

 2 shows the functional principle of a second LED lighting arrangement according to the invention in the form of a cuboid high-power LED lamp; and

 3 shows the block diagram of an overheating protection for an inventive LED lighting arrangement.

WAYS FOR CARRYING OUT THE INVENTION

Figures 1 and 2 illustrate the principle of the inventive method for cooling a arranged on ei ^¬ nem heatsink 1 LED light source 2 based on a first inventive LED lighting arrangement with two circulating flows 8, 9 in the form of a classical lantern (FIG. 1) and with reference to a second inventive LED lighting arrangement with three circulating flows 8, 9, 10 in the form of a high-power LED luminaire with 150 connected load (FIG ).

The lantern shown in Fig. 1 ^" has a cup-shaped, all-round glazed lower housing part 5a (demanding first portion of the housing), which serves in normal operation as exit surface for the light generated by the LED light source 2. To the upper end This housing part 5a encloses a hood-shaped metal cover 5b with ornamental structures (the second part of the housing is required) .The glazed lower housing 5a and the metal cover 5b together form a hermetically sealed lamp housing 5, which is filled with air 6.

 The LED illuminant 2 is arranged on a finger or fin heat sink 1, which is arranged centrally in the transition region between the glazed lower housing part 5 a and the metal cover 5 b and is cooled during normal operation by means of an electrical fan 3 arranged above it.

As can be seen from the arrows indicating the air streams, the blown by the fan 3 in the heat sink 1 Gesamtluftström 4 is divided in the heat sink 1 into two separate fluid streams, which are each deflected by 90 ^° in opposite directions, so that they the heat sink 1 left on opposite sides.

The deflected in the representation on the right from the cooling ^¬ body 1 exiting fluid stream ird from an associated air deflector 7 down and forms a first Umlaufst römung 8, which flows along the inner wall surfaces of the cup-shaped, glass-enclosed lower housing part 5a in the clockwise direction. The left in the illustration left from the heat sink 1 fluid flow is deflected by associated air deflectors 7 upwards and forms a second circulating flow 9, which flows in a clockwise direction along the inner wall surfaces of the hood-shaped metal lid 5b.

 When the lantern is used as intended, the two circulating flows 8, 9 each essentially run in a vertical plane.

 The first circulating flow 8, after having flowed along the wall surfaces of the lower housing part 5a, enters the second circulating flow 9 in the metal cover 5b in the area of the upper end of this housing part 5a, where it then flows together with the second circulating flow 9 along the wall surfaces of the metal cover 5b flows before this total current 4 formed from the first 8 and the second 9 circulating flow reaches the fan 3 again and is conveyed by this again to the heat sink 1.

 As can be seen, flows through the first circulating flow 8 through a narrow slot 12, at which by the flowing second circulating flow 9, a pressure drop is generated {Luftst ompumpe), in the second circulating flow 9 a. It is sucked into the second circulating flow 9 by the generated pressure gradient.

In other words, so the exiting right out of the heat sink 1 airflow verläset the heat sink 1 in the glazed part 5a of the housing 5 and there forms an air cylinder 8, which long strokes corresponds to the glass surfaces, it cools and then to the top Me ^¬ tallteil 5b the housing 5 passes. The flow direction and orientation of this circulating flow 8 is influenced significantly by the suction effect of the slot 12.

This push-pull principle gives the air roller 8 a very high stability. In the metal lid 5b from the first 8 and the second circulation flow 9 club ^¬ te Gesamtiuftström passes over the metal walls of the lid 5b are its heat from it and is sucked in again by the central fan 3. The cooled air then flows through the LED heat sink 1 again and the cycle starts again.

 The high-performance LED shown in FIG.

Luminaire v / eist a large area flat, cuboidal lamp housing 5. Such lights are e.g. used as floodlights, pedestrian crossing lights and tunnel lights. Its housing 5 is formed from a steel-like housing body 5b made of sheet steel (sophisticated second subregion of the housing) whose open side is covered with a cover glass 5a (demanding first subregion of the housing), which in the intended operation is used as exit surface for the light generated by the LED bulb 2 is used. Fig. 2 is a plan view of the side of the luminaire formed by the cover glass 5a.

 The trough-like housing body 5b and the cover glass 5a together form a hermetically sealed lamp housing 5, which is filled with air 6.

 The LED light-emitting means 2 is an LED array which is arranged on a profile heat sink 1, which is arranged in the region of one of the side walls of the trough-like housing body 5b, and in normal operation by means of an electric blower arranged at its right end 3 is cooled.

As seen from the air flows suggestive Pfeiffer ^¬ len is seen passing through the air blown from the blower 3 into the heat sink 1 Gesamtluftström 4 the heatsink 1 as a single air stream, and is mungsleit- directly after its exit from the heat sink 1 by means of currents and -dividing 7 divided into three separate partial streams 8, 9, 10, of which a first circulating flow 8 along the inner wall surfaces of the cover glass 5a forms a second circulating flow 9 ent ^¬ the inner wall surfaces of the rear wall of the trough-like Housing body 5b forms and a third circulating flow 10 along the Innenv / andflächen of three side walls of the trough-like housing body 5b forms.

 The first circulating flow 8 and the second circulating flow 9 are separated from each other over wide areas by a large-area reflector 11 which reflects the light generated by the LED illuminant 2.

 As can be seen, the three circulating flows 8, 9, 10, after being separated from each other along housing wall surfaces of the cover glass 5a (circulation flow 8), the rear wall of the tub-like housing body 5b (circulation flow 9) and the side walls of the tub-like housing body 5b (circulating flow 10) are flowing, in front of the fan 3 again to a total strora 4, which is then passed through the heat sink 1 again.

 When the high-power LED luminaire shown in FIG. 2 is used as intended, all three circulating flows 8, 9, 10 are in each case essentially in a horizontal plane.

 Fig. 3 shows the block diagram of a thermostatic and solar radiation responsive safety or. S tromsparvorrichtung for an inventive LED lighting arrangement, which prevents overheating of the LED light source 2 by means of a reduction of the supply energy or by switching off when too high LED temperatures or housing interior temperatures and / or direct sunlight is detected on the housing 5 ,

This device comprises a sunlight sensor and two temperature sensors, three comparators for interpretation of the setting of the switching values and an OR circuit. With this device, the light power is limited by the amplifier kl to about 30%, if the temperature in the housing 5 is above 50 ° C. or sunlight is detected. With the second amplifier k2, the LED illuminant is completely switched off when the temperature in the housing 5 rises above 70 ° C. The signal combined via diodes is adapted to the globally standardized dimmer standard input (1 ... 10V) of the LED driver by means of an operational amplifier computing stage (y = -u + 10).

 While preferred embodiments of the invention are described in the present application, it should be clearly understood that the invention is not limited to these and may be practiced otherwise within the scope of the following claims.

Claims

claims A method of cooling a LED illuminant (2) disposed on a heat sink (1), comprising the steps of:  a) arranging the heat sink (1) with the arranged thereon LED light source (2) in a fluid-tight, in particular hermetically sealed and with a fluid (6), in particular with air (6), filled housing (5), which has a first portion (5a), in which the housing walls are substantially made of a transparent material, in particular of glass, and serve as an exit surface for the light generated by the LED illuminant (2); and  b) generating at least one circulating flow (8, 9, 10) from the in the housing (5) located fluid (6) within the housing (5) by means of a conveyor (3), in particular by means of a pump or a fan (3), such in that this circulating flow (8, 9, 10) is guided along cooling surfaces of the heat sink (1) and housing wall surfaces and continuously absorbs heat from the heat sink (1) during circulation and delivers it to the housing walls.  2. The method of claim 1, wherein the heat sink (1) in a housing (5) is arranged, which has a second portion (5b), in which the housing walls in bestxmmungsgemässen operation not as an exit surface for the of the LED light source (2 ), and in particular in which the housing walls are essentially made of a non-transparent material, in particular of metal, and wherein the at least one circulation flow (8, 9, 10) is generated such that they (along housing wall surfaces of the first portion (5a) of Ge ^¬ häuses (5) and / or along the housing wall surfaces of the second portion (5b) of the housing 5) is guided. 3. The method of claim 2, wherein as at least one circulating flow a plurality of circulating flows (8, 9, 10), in particular exactly two circulating flows (8, 9) are generated, such that a first circulating flow (8) along cooling surfaces of the heat sink ( 1) and housing wall surfaces of the first portion (5a) of the housing (5) is guided and a second circulating flow (9) along cooling surfaces of the heat sink (1) and housing wall surfaces of the second portion (5b) of the housing (5) becomes.  4. The method of claim 3, wherein the plurality of Umlaufst romans (8, 9, 10) are generated with a common conveyor (3).  A method according to any one of claims 3 to 4, wherein the first recirculation flow (8) is generated to circulate substantially in a vertical plane and the second recirculation flow (9) is generated to be substantially in one vertical or horizontal plane revolves.  6. The method according to any one of claims 3 to 4, 'wherein the plurality of circulating flows (8, 9, 10) are generated such that they each circulate substantially in a horizontal plane. 7. The method according to any one of claims 3 to 6, wherein the first circulating flow (8) is generated such that, after it ge ^¬ leads along housing wall surfaces of the first portion (5a) of the housing (5), in the second Circulation flow (9) is guided and then together with the second circulating flow (9) along housing wall surfaces of the second portion (5 b) of the housing (5) is guided before this from the first (8) and the second (9) circulating ^¬ mung formed Gesamt ström (4) is again led to the heat sink (1).  8. The method according to claim 7, wherein at the Point at which the first circulating flow (8) is guided into the second circulating flow (9) through the flowing second circulating flow (9) a pressure gradient is generated, via which the first circulating flow (8) is sucked into the second circulating flow (9).  9. The method according to any one of claims 3 to 6, wherein the first (8) and the second (9) recirculating flow, after being guided separately from each other along housing wall surfaces of the first (5a) and second (5b) portion of the housing (5) have been brought together, and then as the total current (4) again to the heat sink (1) are performed.  10. The method according to any one of claims 7 to 9, wherein the division of the of the conveyor (3) to the heat sink (1) guided total flow (4) in the heat sink (1), such that the fluid flows, which the first (8) and the second (9) circulating flow, leaving the heat sink (1) at different locations, in particular in opposite directions.  11. The method of claim 10, wherein the fluid streams, which form the first (8) and the second (9) circulating flow, are deflected in the heat sink (1), in particular in each case by 90 °.  12. Method according to. one of claims 7 to 9, wherein the division of the heat sink (1) outgoing total current (4) downstream of the heat sink (1) follows. 13. The method according to any one of the preceding claims, wherein the heat sink (1) is arranged spaced from the housing walls or is arranged in contact with a housing wall, for transmitting heat from the heat sink to the housing by means ^{Wärmelei ¬} tion. 14. The method according to any one of the preceding claims, wherein the delivery rate of the conveyor (3) is regulated in dependence on the ambient temperature. 15. LED lighting arrangement for carrying out the method according to one of the preceding claims, comprising:  a) at least one on a heat sink (1) arranged LED lighting means (2);  b) at least one conveyor (3), in particular a pump or a fan (3), for generating a fluid flow (4) for cooling the heat sink (1); and  c) a fluid-tight, in particular hermetically sealed housing (5), which is filled with a fluid (6), in particular with air (6), wherein the housing (5) has a first portion (5a), in which the housing walls in Substantially consist of a transparent LMaterial, in particular of glass, and serve in intended operation as an exit surface for the light generated on the at least one LED illuminant (2), wherein the heat sink (1) with the LED illuminant (2) arranged thereon and the conveying device (3) are arranged inside the housing (5) and wherein these, in particular i combination with associated flow directors (7), cooperate in such a way that best.immungsgem SEN mode generated with activated conveyor (3) at least one by the conveying means (3) circulating flow (8, 9, 10) of the housing (5) located fluid (6), results in which (along cooling ^¬ surfaces of the heat sink 1) and then flows along housin ^¬ wall surfaces while continuously receives heat from the heat sink (1) and emits to the housing walls. 16. LED Beieuchtungsanorcnung according to claim 15, wherein the housing (5) has a second portion (5b), in which the housing walls in the normal operation not as an exit surface for the light generated by the at least one LED bulb (2) and in particular in which the housing walls are essentially made of a non-transparent material, in particular of metal,  and wherein the lighting arrangement is designed in such a way that during normal operation with activated conveyor (3) the at least one circulating flow (8, 9, 10) along housing wall surfaces of the first portion (5a) of the housing (5) and / or along housing wall surfaces of second portion (5b) of the housing (5) flows.  17. LED lighting arrangement according to claim 16, wherein the illumination arrangement is designed such that during normal operation with activated conveyor (3) at least two circulating flows (8, 9, 10) result, of which a first circulating flow (8) along housing wall surfaces of the first portion (5a) of the Housing (5) flows and a second circulating flow (9) along housing wall surfaces of the second portion (5b) of the housing (5) flows.  18. LED lighting arrangement according to claim 17, wherein the illumination arrangement is designed such that the at least two circulating flows (8, 9, 10) are generated by the same conveying device (3).  19. LED lighting arrangement according to one of claims 17 to 18, wherein the illumination arrangement is formed such that the first circulating flow (8) rotates substantially in a vertical plane and the second circulating flow (9) rotates substantially in a vertical or horizontal plane ,  20. LED lighting arrangement according to one of claims 17 to 18, wherein the illumination arrangement is formed such that the circulating flows (8, 9, 10) rotate substantially in a horizontal plane. 21. LED lighting arrangement according to one of claims 17 to 20, wherein the lighting arrangement is formed such that the first circulating flow (8), after being along housing wall surfaces of the first Part of the housing (5) has flowed into the second circulating flow (9) and then together with the second circulating flow (9) along housing wall surfaces of the second portion (5 b) of the housing (5) flows before it from the the first (8) and the second (9) circulating flow formed total flow (4) flows again to the heat sink (1).  22. LED lighting arrangement according to claim 21, wherein the lighting arrangement is designed such that at the point (12) at which the first circulating flow (8) enters the second circulating flow (9), by the flowing zv / eite circulating flow (9 ), a pressure gradient is generated, which sucks the first circulating flow (8) in the zv / eite circulation flow (9). The LED lighting device according to any one of claims 17 to 20, wherein the lighting device is formed such that the first circulating flow (8) has flowed along housing wall surfaces of the first portion (5a) of the housing (5), and the second Circulating flow (9) after it has flowed along Gehau sebo surface of the second portion (5 b) of the housing (5), flow together and then as a total ^¬ current (4) back to the heat sink (1) flow.  24. LED lighting arrangement according to one of claims 21 to 23, wherein the illumination arrangement is formed such that the division of the of the conveyor (3) to the heat sink (1) outgoing total current (4) in the heat sink (1), so, the fluid streams which form the first (8) and the second (9) circulating flow leave the heat sink (1) at different locations, in particular in opposite directions. 25. LED lighting arrangement according to one of claims 21 to 23, wherein the lighting arrangement is formed so that the division of the cooling body ^¬ (1) guided total current (4) downstream of the heat sink (1). 26. LED lighting arrangement according to one of claims 15 to 25, wherein the heat sink (1) is spaced from the housing walls or is in contact with a housing wall, for transmitting heat from the heat sink to the housing wall by means of heat conduction.  27. LED lighting arrangement according to one of claims 15 to 26, further comprising a reflector (11) for reflecting and / or focusing the light generated by the LED light source (2), wherein the reflector (11) in the intended operation serves as Strömungsleiteinrichtu g for the at least one circulating flow and / or as a heat sink for the at least one LED bulb.  28. LED lighting arrangement according to one of claims 15 to 27, wherein the housing (5) is filled with a fluid other than air (6), in particular with hydrogen, helium, fluorocarbon, nitrogen, carbon dioxide or Schweielhexafluorid.  29. LED lighting arrangement according to one of claims 15 to 28, wherein the fluid (6) in the housing (5) is under an overpressure.  30. LED lighting arrangement according to claim 15, further comprising, arranged in the housing (5) in a region through which the fluid (6) flows or flows around during normal operation when the conveying device (3) is activated, Means for retaining dirt particles and / or for preventing condensation, in particular fine filters, electrostatic precipitators, zeolites and / or adsorbents, in particular silica gel. 31. LED lighting arrangement according to one of claims 15 to 30, further comprising thermostatic and / or responsive to sunlight security or. Power saving devices, which overheat the LED illuminant (2) by means of a reduction of the supply energy or energy consumption. prevent by switching off, if too high LED temperatures, housing interior temperatures and / or direct sunlight on the housing (5) are detected.  32. The LED lighting assembly according to claim 15, further comprising means for adjusting the power of the conveyor in dependence on the ambient temperature to the currently required heat transfer capacity.