EP2235436A1

EP2235436A1 - Led lamp with cooling liquid

Info

Publication number: EP2235436A1
Application number: EP08871542A
Authority: EP
Inventors: Gerald Ladstätter; Erich Schwärzler
Original assignee: Zumtobel Lighting GmbH Austria
Current assignee: Zumtobel Lighting GmbH Austria
Priority date: 2008-01-23
Filing date: 2008-10-17
Publication date: 2010-10-06
Also published as: DE102008005697A1; WO2009092405A1

Abstract

The invention relates to a lamp comprising an LED (2) and a cooling body (4) for cooling the LED (2). The LED (2) is arranged in a pivotal manner in relation to the cooling body (4). The lamp further comprises a cooling liquid (8), for example water, for the heat transfer from the LED (2) to the cooling body (4). A receiving chamber (10) that is delimited by the cooling body (4), a membrane (6) and a carrier element (14) for a circuit board (12) of the LED (2) can be provided for the cooling liquid (8). For arresting the LED (2) in a certain position in relation to the cooling body (4), arresting means, for example detent elements in the form of recesses (50) and engaging elements (51), can be provided. As the LED (2) can be pivoted in relation to the cooling body (4), a separate optical element for changing the direction of the light emission is not necessary. Furthermore, the cooling body (4) does not have to be arranged in a pivotal manner, so that a comparatively small size of the luminaire can be implemented.

Description

LED light with coolant

The invention relates to a luminaire with an LED (light-emitting diode) and a heat sink for cooling the LED.

For LED luminaires, it is generally necessary to ensure that the heat generated by the LED during operation is effectively dissipated "point-like." For this purpose, heatsinks are usually used that are comparatively large in accordance with this function.

In the case of LED lights, in which the direction of the light output can be selectively changed, so for example in LED spots or LED spotlights, is usually provided for the realization of this Richtungsveränderlichkeit that the LED and the heat sink are arranged rigidly relative to each other and either the LED and the heat sink can be adjusted together or an optical element, which is arranged in the emission direction in front of the LED, can be adjusted.

The invention is based on the object to provide an LED lamp with an effective cooling of the LED, in which the direction of the light output can be changed and which can be carried out small volume and is easy to manufacture.

This object is achieved according to the invention with the object mentioned in the independent claim. Particular embodiments are given in the dependent claims.

According to the invention, a luminaire is provided with at least one LED and a heat sink for cooling the LED. The LED is arranged pivotably relative to the heat sink and the lamp further comprises a cooling liquid for heat transfer from the LED to the heat sink.

Since the LED can be pivoted with respect to the heat sink, a separate optical element for changing the direction of the light output is not required; In addition, the heat sink does not have to be pivotable per se, so that an overall comparatively small size of the luminaire can be realized. In spite of the mutual adjustability between the LED and the heat sink, ie despite the "decoupling" between the LED and the heat sink, a good heat dissipation from the LED can be ensured by using the cooling liquid Swiveling mechanism of the LED would be provided with respect to the heat sink, can be made possible by the use of the cooling liquid significantly larger contact surfaces for heat transfer, thus in principle a much more effective heat transfer can be achieved because a corresponding pivot mechanism would have several parts that only point or line contacts For the components that are provided in the luminaire according to the invention for pivoting the LED, therefore, only relatively small mutual contact surfaces must be provided and also are relatively small forces on the These contact surfaces act sufficiently.

Furthermore, in comparison to a heat conduction via a solid body in the case of heat conduction via a liquid, a convective transport of heat may occur; It is so far provided an "additional" Wärmeleitmöglichkeit.

Advantageously, the luminaire further comprises a receiving space for the cooling liquid, wherein the receiving space is partially bounded by the heat sink and partially by a membrane. In this case, the membrane is advantageously connected to the LED such that upon pivoting of the LED, the membrane is deformed. Through the membrane, a flexibility can be achieved with which the pivoting of the LED relative to the heat sink is possible. Furthermore, by using the membrane, the number of components that are provided for pivoting the LED can be kept very small; This is conducive to a particularly direct heat flow from the LED to the heat sink.

Furthermore, the LED is advantageously arranged on a circuit board and the

Recording room still partially limited by the board. However, it is also advantageously possible for the LED to be arranged on a circuit board, wherein the luminaire furthermore has a carrier element for the circuit board and the receiving space is furthermore partially bounded by the carrier element and / or partially by the circuit board. In this case, advantageously, the carrier element further form a reflector for the LED.

For example, it can thus be provided that the receiving space is limited exclusively by the heat sink, the membrane and the carrier element. It can also For example, be provided that the receiving space is limited only by the heat sink, the membrane, the support member and the board.

Advantageously, the cooling liquid comprises water. At about 4180 J / kg K., water has a comparatively high heat capacity, in particular an approximately four times greater heat capacity than air, and can thus absorb a corresponding amount of heat. The thermal conductivity of water at 0.6 W / mK is significantly better than that of air (0.024 WM).

Further advantageously, the cooling liquid contains at least one additive for increasing the thermal conductivity.

Advantageously, the luminaire further comprises at least one heat pipe for heat transfer from the LED to the cooling liquid and / or to the heat sink. In this case, furthermore, the heat pipe can advantageously be arranged in a positionally stable manner relative to the LED.

Advantageously, the lamp further comprises locking means for locking the LED relative to the heat sink. In this case, advantageously, a part of the locking means may be formed by the heat sink. The locking means may comprise locking elements. If a heat pipe is provided, a part of the locking means may be formed by the heat pipe.

The invention is explained in more detail below with reference to exemplary embodiments and with reference to the drawings. Show it:

1 is a sketch of a first embodiment of a lamp according to the invention in a cutaway form,

2a to 2d sketches for different variants of a connection between the LED and the membrane of an inventive

Lamp,

3a and 3b sketches to a first variant of the membrane design,

4a and 4b sketches to a second variant of the membrane design,

5a and 5b sketches to a third variant of the membrane design, 6 is a sketch of a variant of the restraint, and

7 shows a sketch of a further variant of the restraining means.

In Fig. 1, a first embodiment of a ertlndungsgemäßen lamp in the form of an LED spot is sketched in the cut state. The lamp has an LED 2, which serves as a light source. It can also be provided as a light source multiple LEDs. With an arrow P while the main emission of the LED 2 and the lamp is outlined. The LED 2 may be a so-called high-power LED. Next, the lamp has a heat sink 4, which serves to cool the LED 2 or, where appropriate, the LEDs in the operating state. The heat sink 4 may have cooling fins 5.

The LED 2 is arranged so that it can be pivoted relative to the heat sink 4. By such pivoting, the direction of the light output of the lamp can be selectively changed without the heat sink 4 must be changed in its position. Various possibilities for realizing the pivotability of the LED 2 with respect to the heat sink 4 are shown below.

Furthermore, the lamp has a cooling liquid 8, which serves for heat transfer from the LED 2 to the heat sink 4. The heat transfer from the LED 2 to the heat sink 4 is thus at least partially provided by the cooling liquid 8. By using the cooling liquid 8, a particularly large-area and therefore effective heat transfer from the LED 2 to the heat sink 4 is made possible.

The cooling liquid 8 may include water. For example, the cooling liquid 8 may be water. However, other liquids that allow good heat transfer, as a cooling liquid possible. Furthermore, the cooling liquid 8 may contain a known additive, which serves to increase the thermal conductivity. Of course, several such additives may be provided.

In the case of the embodiment shown here, the luminaire has a closed receiving space 10 for the cooling liquid 8. The receiving space 10 may be partially bounded by the heat sink 4 and partially by a membrane 6. The membrane 6 is provided sufficiently tight for the cooling liquid 8. If the cooling liquid 8 is water, the membrane 6 is therefore provided watertight. In the case of the exemplary embodiment sketched in FIG. 1, the heat sink 4 has a preferably cylindrical side wall 20 which is arranged in a ring-shaped manner around the LED 2, the side wall 20 having an edge region at the end region pointing in the direction of the light emission of the LED 2 22, which is provided for connection to the membrane 6.

In this embodiment, the membrane 6 is substantially annular and has an outer edge region 61 and an inner edge region 62. With its outer edge region 61, the membrane 6 is firmly and at least substantially impermeable to the cooling liquid 8 directly connected to the edge region 22 of the side wall 20 of the heat sink 4. With its inner edge region 62, the membrane is fixed directly or indirectly fixed and at least substantially impermeable to the cooling liquid 8 with the LED 2.

The membrane 6 is made of an elastic material, so that the membrane 6 is deformed when the LED 2 is pivoted relative to the heat sink 4. The membrane 6 is "freely adjustable" and for this purpose preferably has at least one wave-shaped section, Furthermore, the membrane 6 is designed to be prestressed, thereby facilitating a lockability of the LED 2 in a specific position relative to the heat sink 4 ,

Furthermore, the LED 2 is arranged on a circuit board 12 in the exemplary embodiment. In the embodiment sketched in FIG. 1, a carrier element 14 for the circuit board 12 is furthermore provided, wherein the receiving space 10 of the cooling liquid 8 is furthermore partially bounded by the carrier element 14. Overall, therefore, in the embodiment shown in Fig. 1, the receiving space 10 of the heat sink 4, the diaphragm 6 and the support member 14 is limited. Of course, the boundary surfaces of the heat sink 4 and the support member 14 to the receiving space 10 are provided tightly for the cooling liquid 8. If the cooling liquid 8 is water, the area mentioned can therefore be provided watertight.

With regard to the limitation of the receiving space 10 for the cooling liquid 8, however, variants are possible. The reference numerals used below for variants refer to corresponding parts.

A variant is sketched in FIG. 2a; In this case, it is provided that the membrane 6 is connected with its inner edge region 62 directly to the circuit board 12 and the circuit board 12 also partially limits the receiving space 10, so that a direct Contact between the back of the board 12 (ie, the side of the board 12, which is opposite to the LED 2) and the cooling liquid 8 is given. In this variant, therefore, no support element 14 is provided and therefore this configuration represents in a certain sense with respect to the heat transfer the "ideal configuration". According to the sketched in Fig. 2b variant is also provided that the board 12 partially limits the receiving space 10, but is Furthermore, a carrier element 14 is provided for the circuit board 12, which likewise partially delimits the receiving space 10. The circuit board 12 is held at its periphery by the carrier element 14. According to the variant shown in Fig. 2c, the circuit board 12 is held by the carrier element 14, However, the board 12 does not contribute to the limitation of the receiving space 19. The carrier element 14, however, partially limits the receiving space 10. The heat flow from the LED 2 to the cooling liquid 8 takes place here via the carrier element 14.

In general, if appropriate, a particularly good heat-conducting material, for example aluminum, is provided for the carrier element 14.

Optionally, it may be provided that the carrier element 14 forms a reflector 13 for the LED 2, as sketched in FIG. 1, for example.

In the figures 3a and 3b, a variant of the design of the membrane 6 is sketched. In this variant, the carrier element 14 has a flange-like edge region 15, which is connected to the membrane 6. In this variant, the membrane 6 extends essentially along the inside of the side wall 20 of the heat sink 4 and is thus protected from external influences by it. As outlined in Fig. 3a, a neutral position of the LED 2 with respect to the heat sink 4 is possible in this way, in which the membrane 6 from outside the lamp is virtually impossible to see, as they in particular from the side wall 20 of the heat sink 4 and the edge region 15 of the support member 14 is hidden.

In the variant which is outlined in the corresponding FIGS. 4 a and 4 b, the cooling body 4 has at its boundary surface to the receiving space 10 further cooling ribs 5 'for further enlarging the contact surface between the cooling liquid 8 and the cooling body 4.

In the variant outlined in the corresponding FIGS. 5a and 5b, the heat sink 4 has a region which surrounds the LED 2 in an annular manner. In addition, two membranes 6, 6 'are provided, each between the carrier element 14 and the heat sink 4 extend. This variant allows a particularly harsh design of the lamp.

When considering the variants shown, of course, there are further, not shown in detail further variants, in an obvious way. For example, in the variant shown in Fig. 5a, it may be provided that the heat sink has further cooling fins corresponding to those shown in Fig. 4a, etc.

According to a further variant, which is outlined in FIG. 7, a so-called heat pipe 18 known per se is provided for further improving the heat conduction from the LED 2 to the cooling liquid 8 or to the cooling body 4. In the heat pipe 18 is an elongated, closed, hollow tube, which is partially filled with a liquid; the liquid accumulates at the warmer end of the tube and vaporizes accordingly, with heat dissipated at the opposite end of the tube. The use of a heat pipe 18 is particularly suitable if the distance between the LED 2 and the cooling liquid 8 is comparatively large, as is the case, for example, in the variant shown in FIG.

A possible connection between the heat pipe 18 and the LED 2 is outlined in Fig. 2d. Here, a carrier element 30 is provided for the heat pipe 18, which is arranged between the inner edge region 62 of the membrane 6 and the heat pipe 18. The LED 2 can be arranged fixed position relative to the heat pipe 18.

Referring again to FIG. 1, in the exemplary embodiment shown there are further provided locking means 16 which serve to lock the LED 2 relative to the heat sink 4 in different relative positions. The locking means 16 may for example have projections and / or recesses 50, which are arranged on the heat sink 4, in which corresponding engagement elements 51, which are fixedly connected to the LED 2, can engage latching. In the embodiment shown, the recesses 50 are arranged on the boundary surface of the heat sink 4 to the receiving space 10 of the cooling liquid 8; the engagement elements 51 are arranged on the carrier element 14 of the circuit board 12. For this purpose, the carrier element 14 is correspondingly extended at its end region, which faces away from the main emission direction P, so that cooperation of the engagement elements 51 with the depressions 50 is possible in the above-mentioned sense. As sketched in FIG. 1, it can be provided that the support member 14 is widened at its end portion, which is intended for direct contact with the heat sink 4, so that the possibility of transferring heat at this point is improved. This is particularly advantageous if the thermal conductivity of the carrier element 14 is greater than that of the cooling liquid. For example, this may be the case if water is provided as the cooling liquid and the carrier element 14 consists of aluminum. (The thermal conductivity of aluminum is about 237 W / mK, that of water about 0.6 W / mK.)

In Fig. 6 a variant of the locking means 16 is outlined. Here, two arcuate, mutually orthogonal tooth combs are provided, which can interlock latching; one of the two tooth combs is arranged on the heat sink 4, the other on the support element 14th

In the variant shown in FIG. 7, it is advantageously provided that the heat pipe 18 forms part of the locking means 16. In this case, it is further provided that the heat pipe 18 directly contacts the heat sink 4 with that end region which is opposite the LED 2 or the circuit board 12; For this purpose, annular recesses are provided on the heat sink 4, in which the heat pipe 18 can engage.

As indicated in FIGS. 3 a, 3 b, 4 a and 4 b, according to a further variant, the locking means can comprise a projection which is arranged on the heat sink 4 and depressions which are arranged on the carrier element 14, this projection and these depressions being provided for this purpose, latching together.

It should be mentioned again that the variants shown can be combined in many ways. The possible combinations result from expert consideration in a self-explanatory manner.

It should be pointed out that the use of the cooling liquid 8 for the luminaire according to the invention generally results in a preferred orientation with respect to an effective heat transport from the LED 2 to the cooling body 4. If the heat sink 4 is arranged above the LED 2, the heat transfer is more effective than in the opposite case. It results in this sense, a preferred mounting position for the lamp according to the invention.

It is finally again noted that the advantage of using the iMembrane 6 is that thereby the number of components that pivot the LED 2 required can be reduced. By the use of the cooling liquid 8 großtlächige contact areas for the heat transfer from the LED 2 to the heat sink 4 allows, so that a particularly effective heat dissipation from the LED 2 is possible. In addition, a cooling liquid 8 with a high heat capacity can be selected, for example water, so that the cooling liquid 8 itself can absorb heat from the LED 2 to a significant degree.

LIST OF REFERENCE NUMBERS

2 LED 4 heat sink

5 cooling fins

5 'further cooling ribs

6 membrane

6 'second membrane 8 cooling liquid

IO receiving space for the coolant

12 board

13 reflector

14 carrier element for the board 15 edge region of the carrier element for the board

16 locking means

18 heatpipe

20 side wall of the heat sink

22 edge region of the side wall of the heat sink 30 carrier element for the heat pipe

50 wells

51 engaging elements

61 outer edge region of the membrane

62 inner edge region of the membrane

Claims

claims

1. luminaire, comprising - at least one LED (2), and

- A heat sink (4) for cooling the LED (2), characterized in that the LED (2) relative to the heat sink (4) is pivotally mounted and that the lamp further comprises a cooling liquid (8) for heat transfer from the LED (2) to the heat sink (4).

2. Lamp according to claim 1, further comprising a receiving space (10) for the cooling liquid (8), wherein the receiving space (10) is partially bounded by the heat sink (4) and partially by a membrane (6).

3. Lamp according to claim 2, wherein the membrane (6) is connected to the LED (2) such that upon pivoting of the LED (2), the membrane (6) is deformed.

4. Lamp according to claim 2 or 3, wherein the LED (2) on a circuit board (12) is arranged and the receiving space (10) is further partially bounded by the board (12).

5. Lamp according to claim 2 or 3, wherein the LED (2) on a circuit board (12) is arranged, wherein the lamp further comprises a support member (14) for the board (12) and the receiving space (10) continues partially from the support element (14) and / or partially bounded by the circuit board (12).

6. Lamp according to claim 5, wherein the carrier element (14) further forms a reflector (13) for the LED (2).

7. Lamp according to one of the preceding claims, wherein the cooling liquid (8) comprises water.

8. Lamp according to claim 7, wherein the cooling liquid (8) further comprises at least one addition to Increase in thermal conductivity contains.

⁽ ). Luminaire according to one of the preceding claims, wherein the luminaire further comprises at least one heat pipe (18) for heat transfer from the LED (2) to the cooling liquid (8) and / or to the

Includes heat sink (4).

10. Luminaire according to claim 8, wherein the heat pipe (18) is arranged fixed in position relative to the LED (2).

1 1. Lamp according to one of the preceding claims, wherein the lamp further comprises locking means (16) for locking the LED (2) relative to the heat sink (4).

12. Lamp according to claim 1 1, wherein a part of the locking elements (16) of the heat sink (4) is formed.

13. Light according to claim 1 1 or 12, wherein the locking means (16) locking elements (50, 51).

14. Luminaire with the features mentioned in claims 9 and 11, wherein a part of the locking means (16) through the heat pipe (18) is formed.