WO2008128635A1

WO2008128635A1 - Light with a cooling system

Info

Publication number: WO2008128635A1
Application number: PCT/EP2008/002742
Authority: WO
Inventors: Gerald Ladstätter; Erich Schwärzler; Günther SEJKORA
Original assignee: Zumtobel Lighting Gmbh; Ledon Lighting Gmbh
Priority date: 2007-04-23
Filing date: 2008-04-07
Publication date: 2008-10-30
Also published as: EP2137458A1; EP2137458B1; DE102007019074A1

Abstract

The invention relates to a light, especially a recessed downlight comprising a housing (1), a light source, for example at least one LED (2), arranged inside the housing, and a device for producing a gas flow for cooling the light source (2), said gas flow being guided through the housing (1). The device comprises a pump (3), for example a diaphragm or piston pump. The device may be driven, for example, by a Stirling engine (30), a motor or a system consisting of a magnetic coil and a solenoid. The system according to the invention allows the heat that is produced during operation of the light (2) to be dissipated effectively and with little noise. When a Stirling engine (30) is used, the heat of the light source (2) can be utilized for driving the Stirling engine (30).

Description

Lamp with cooling

The present invention relates to a luminaire, in particular a recessed ceiling luminaire with a housing, a light source disposed within the housing and a device for generating a guided through the housing gas flow for cooling the light source.

As a rule, a light source of a luminaire heats up during operation of the luminaire, so that in general the problem of cooling the light source or the luminaire is given. For example, if the light source is a light-emitting diode (LED), the light flux produced by the LED will be smaller under normal conditions the warmer the LED is. In addition, the life of an LED is usually reduced if it is not cooled during operation. In general, there is the problem that LEDs must be effectively cooled in order to operate at the best possible level of performance can.

In surface or pendant lights with light sources in the form of LEDs, it is known to form the housing of the lamp as a heat sink, on the surface of which a convection flow can form, with which the excess heat is dissipated, so that the lamp is cooled in this way.

Furthermore, it is known to cool the LEDs of a lamp with the help of a fan. Due to the high speeds that occur in such fans, however, bearing noise is inevitable. The lifetime of such fans, which is typically a few thousand hours, is relatively limited.

In the case of recessed ceiling luminaires, for example in the form of downlights, however, there may be the problem that no corresponding free convection flow or air circulation can form, namely if the heat sink of the luminaire is installed in an upwardly closed installation opening in the ceiling is. The invention is based on the object to provide a lamp whose light source can be effectively cooled, especially in the case that no free convection flow can form.

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

According to the invention, there is provided a luminaire, in particular a recessed ceiling luminaire, which has a housing, a light source arranged inside the housing, and a device for generating a gas flow guided through the housing for cooling the light source. The device comprises a pump. The gas stream may be, for example, an air stream. The luminaire can also be, for example, a recessed wall luminaire.

In this way, with the aid of a forced gas or air flow, effective cooling of the light source can be achieved, in particular also in the case that no free convection can form at the top with which the heat generated by the light source is removed could. This may for example be the case when the lamp is installed in an opening which is closed at the top, so for example in a recessed ceiling light, which is installed in a corresponding Deckenöffhung.

A particularly effective heat dissipation is possible when the gas stream passes through a plane which - when the lamp is aligned with respect to the vertical operation - the housing passes horizontally and thereby passes through the light source or above the light source. For example, in the case of a recessed ceiling light, said plane may be the ceiling plane, that is to say that plane which is defined by the underside of the ceiling which, when installed, surrounds the luminaire. In this way, therefore, by means of the pump a forced

Gas flow are generated, with the heat that is generated during operation of the lamp from the light source and accumulates above the light source, are transported down into the space outside the lamp. Advantageously, the light source comprises at least one LED.

Advantageously, the pump is a positive displacement pump, in particular a piston pump or a diaphragm pump. Compared to a fan, such pumps can be operated to perform slower movements. This has the advantage that a quieter operation is possible. In addition, such pumps generally have a longer life. A diaphragm pump is particularly advantageous because, in this case, seal problems between piston and cylinder can not occur in comparison with a piston pump.

Advantageously, the pump comprises a pumping chamber and an outlet channel for the gas flow, wherein the outlet channel connects the pumping chamber with the space outside the luminaire. The term "pumping chamber" here refers to that space in the pump in which the compression of the gas takes place, which is caused by the movement of the displacement body of the pump, for example, the piston or the membrane.

This allows effective gas flow from the pumping chamber. For example, the exhaust passage may terminate at an exhaust port located in a wall of the housing of the lamp so that gas from the exhaust port may flow into the space outside the lamp. The outlet opening can be arranged in the above-mentioned plane, that is, for example, in the intended ceiling plane.

Furthermore, the pump may comprise an inlet channel for the gas flow, which connects the outer space of the lamp with the pumping chamber. In this way, an effective flow into the pumping chamber is made possible. For example, the inlet duct may begin at an inlet opening located in a wall of the housing of the luminaire so that gas from the space outside the luminaire can effectively flow into the pumping chamber. The inlet opening can be arranged in the above-mentioned plane, that is, for example, in the intended ceiling plane.

Advantageously, valves for controlling the direction of the gas flow are arranged at the inlet channel and at the outlet channel. A particularly effective gas flow may be generated if the pump further comprises a second pumping chamber.

Further advantageously, the lamp has an electric motor for driving the pump, wherein preferably a device is provided, with which the rotational movement of the electric motor via a crank drive or an eccentric can be converted into a linear movement.

It can also be advantageously provided that the luminaire has a system for driving the pump, which comprises a magnetic coil and a submersible magnet. This is advantageous because in this case no corresponding rotational movement is required in comparison to a drive with an electric motor; With such a rotational movement wear and increased noise is inevitably connected. It is particularly advantageous that the coil can be operated with a low-frequency alternating voltage, preferably less than 20 Hz. This allows a particularly quiet operation.

It may also be advantageously provided that for controlling the pump, a break contact is provided, which preferably opens when the displacement body, so for example, the piston of the pump is in an extreme position. It can also be advantageously provided that a piezoelectric actuator, for example a bimorph, is provided for controlling the pump,

Particularly advantageously, a Stirling engine is provided for driving the pump. The light source may in this case be thermally connected to the "hot region" of the Stirling engine, thus allowing the heat generated by the light source to be used to drive the pump The Stirling engine may also advantageously be a flat plate Stirling engine, the light source accordingly This form of Stirling engine already works with comparatively very small temperature differences

Flat plate Stirling engine comparatively simple in construction and in the production and can be made very small in size and in particular very flat dimensions, which is advantageous in terms of the size of the lamp. The invention will be explained in more detail below with reference to exemplary embodiments and with reference to the drawings. Show it:

1 is a sketch of a lamp according to the invention with a driven by a Stirling engine diaphragm pump,

2 shows a sketch of an embodiment with a piston pump,

3 is a sketch of an embodiment with a diaphragm pump,

4 is a sketch of an embodiment with two Purnpkammern, wherein the pump is driven by an electric motor,

5 is a sketch of a pump drive by means of a bimetallic control,

Fig. 6 is a sketch of a pump drive by means of a magnetic coil and a submersible magnet, and

Fig. 7 is a sketch of an alternative channel guide.

Fig. 1 shows a sketch of a lamp according to the invention. The luminaire may in particular be a recessed ceiling luminaire which is intended to be installed in a corresponding installation opening in a ceiling 4. The installation opening may, for example, be an opening which is closed at the top, so that there is generally the problem of cooling the luminaire.

One recognizes a housing 1 of the lamp and a light source in the form of LEDs 2, which are arranged in the housing 1 or on its underside, that they - if the lamp is aligned in accordance with the operation - emit light in the lower half-space.

Furthermore, the lamp comprises a region which can be referred to as a heat sink 7 and in which a generally designated 3 pump is arranged, which is adapted to a gas flow - in the example shown, an air flow - to generate, which serves to cool the light source or the LEDs 2. The heat sink 7 extends at least partially above the light source 2. The gas flow is guided through the housing 1 or through the heat sink 7. With the help of the pump 3, therefore, an air flow can be generated which at least to a considerable extent removes the heat which is generated by the LEDs 2 during operation of the luminaire.

In the exemplary embodiment shown in Fig. 1, the pump 3 is a diaphragm pump 3 'with a membrane 12. The diaphragm pump 3' further comprises a pumping chamber 5, the bottom of the membrane 12, laterally from the inner surface of a pumping cylinder 6 and top of a pump chamber ceiling 14 is limited. The membrane 12 moves in operation with a central region alternately up and down, as indicated by the double arrow 13 in Fig. 1 and acts in this way as a displacement of the pump 3 to the air located in the pump chamber 5.

Furthermore, one recognizes an inlet channel 9 arranged in the heat sink 7, which leads from the space outside of the housing 1 of the luminaire - or briefly outer space AR - into the pumping chamber 5, so that air, from the outside space AR through the inlet channel 9 into the interior of the pumping chamber 5 can flow. At the transition from the outer space AR in the housing 1, an inlet opening 11 is provided.

In the example sketched, the inlet opening 11 lies in a plane E, which extends horizontally and thus above the LEDs 2 through the housing 1 or the heat sink 7 when the lamp is in the proper position. The plane E can, for example - as sketched in FIG. 1 - coincide with that plane which is usually referred to as the ceiling plane DE, ie with the plane defined by the underside of the ceiling 4, which surrounds the luminaire in the installed state of the luminaire ,

Furthermore, one recognizes an outlet channel 8, which connects the interior of the pumping chamber 5 with the outer space AR, so that the gas or the air can flow from the pumping chamber 5 into the outer space AR. At the transition between the outlet channel 8 and the outer space AR an outlet 10 is provided. By choosing an appropriate dimensioning of the channels 8, 9 can be taken in a relatively simple manner influence on the air flow.

In order to determine the flow direction, the pump 3 'further comprises a suction or inlet valve 21, which may be arranged for example at the transition between the inlet channel 9 and the pumping chamber 5 and allows air flow from the outer space AR into the pumping chamber 5, but blocks in the opposite direction , A pressure or exhaust valve 20, which may be provided for example at the transition from the outlet channel 8 to the outer space AR, allows an air flow from the pumping chamber 5 in the outer space AR, but locks in the opposite direction.

With the described arrangement, it is possible to form an air flow that passes through the horizontal plane E, in particular penetrated from top to bottom and in this way can particularly effectively remove the heat generated by the LEDs 2 in the outer space AR. In the example sketched, therefore, the heat sink 7 has a channel system formed from the inlet channel 9 and the outlet channel 8, which allows an air flow from the ceiling level DE upwards into the pumping chamber 5 on the one hand and from the pumping chamber 5 downwards via the outlet opening 10 into the outside space AR on the other hand allows.

However, the arrangement is also suitable, for example, for a recessed wall luminaire, namely with a corresponding rotated by 90 ° orientation. In this case, therefore, with an inventive lamp, an effective air flow through a vertical plane from the interior of the lamp can be effected in the outer space.

In the embodiment sketched in FIG. 1, a Stirling engine is provided for driving the diaphragm pump 3 ', in the form of a flat plate Stirling engine 30 with a lower flat plate or end plate 31 forming the "hot region" of the Stirling engine 30 and an upper one End plate 32, which forms the "cold area" of the Stirling engine 30.

The light source or LEDs 2 are thermally connected to the end plate 31, which forms the hot region. The other end plate 32 is thermally connected to the heat sink 7. Between the two plates 31, 32, a cylindrical working chamber is formed, in which a porous working piston 33 of the Stirling engine 30 can move. The Stirling engine 30 draws its energy from the temperature difference of the two end plates 31, 32. About the linear movement of the working piston 33 of the displacer, in this case the diaphragm 12 of the pump 3 is moved. The flow of air generated by the pump 3 cools the "cold" plate 32 of the Stirling engine 30 via the heat sink 7, thus maintaining the temperature difference not discussed in detail.

The use of a Stirling engine to drive the pump is advantageous because in this way the existing thermal energy in the system can be used to drive the pump. An external energy source, for example in the form of electric current, is therefore not absolutely necessary here. A flat plate Stirling engine is particularly suitable because with this type of engine already a comparatively very small temperature difference to the drive is sufficient. In addition, a flat plate Stirling engine is relatively simple in construction and can be produced with relatively few components. Furthermore, it is possible to make the shape of the engine very flat, which is particularly advantageous for use in a lamp.

According to a variant, a piston pump 3 "is provided instead of a diaphragm pump 3 ', separately sketched in Fig. 3, as sketched in Fig. 2. Instead of a diaphragm 12, in this case a piston 15 acts as displacer on the pump chamber 5 The up and down movement of the piston 15 is indicated by a double arrow 16 in FIG.

It can therefore be provided that the pump is a piston pump 3 '', which is driven by a Stirling engine 30.

Both diaphragm pumps and piston pumps are positive displacement pumps. Compared to a fan, a positive displacement pump can be operated so that it runs slower. This is advantageous because bearing noise is unavoidable due to the high speeds that typically occur during fan operation. A Positive displacement pump can therefore generally be operated quieter. In addition, the average life of a positive displacement pump is longer than that of a fan.

A diaphragm pump has the advantage over a piston pump that

Sealing problems of the piston relative to the cylinder in which the piston is running, can be avoided.

As outlined in FIG. 7, furthermore, according to a variant in the membrane 12, valve flaps 27 can be formed which act as inlet and outlet valves. In this case, therefore, the membrane 12 and the valve technology can be realized in one part. In the variant sketched in FIG. 7, the channel guide is arranged on the circumference of the pump cylinder 6. With respect to the inlet opening 11 and the outlet opening 12, it is generally advantageous if these two openings are clearly spaced, for example, substantially located on opposite areas on the underside of a recessed ceiling light to avoid heated air exiting the outlet opening quasi directly followed by the inlet opening to a considerable extent again.

As indicated in FIG. 4, as an alternative to a Stirling engine for driving the

Pump may be provided, for example, an electric motor 22. The rotating movement of the electric motor 22 can be set, for example via a crank drive or an eccentric in a linear motion, which can then be used to drive the pump 3, so for example a diaphragm pump 3 'or a piston pump 3 ".

As further illustrated by way of example in FIG. 4, it can be provided that the pump 3 also has a second pumping chamber 5 'which is connected to the inlet channel 9 via a second inlet valve 21' and to the outlet channel 8 via a second outlet valve 20 ' By such a two-chamber system, the effectiveness of the pump 3 can be further increased. A corresponding two-chamber system can also be realized in the case of a piston pump. As outlined in FIG. 6, another possibility for driving the pump 3 is to generate the linear motion directly. For example, a system with a magnetic coil 24 and a submersible magnet 26 may be provided for this purpose. The coil 24 is connected to the displacement of the pump 3, in the example shown so with the membrane 12. The solenoid 26 is firmly connected to the heat sink 7. The coil 24 moves in its longitudinal direction, in the example sketched in the vertical direction and thereby includes the heat sink 7 more or less deep. In this way, wear can be further reduced and further reduce noise during operation. In this case, it is particularly advantageous with regard to the noise development when the coil 24 is operated with a low-frequency alternating voltage, for example <20 Hz.

In the variant shown in Fig. 6, the pump - as outlined - again have two pumping chambers 5, 5 '. Of course, a variant with only one pumping chamber is possible.

Furthermore, it may alternatively be provided that the control of the pump also takes place directly, for example with a break contact, which opens when the displacement body, that is, for example, the piston is in an extreme position. For a return of the displacer may be provided in this case, for example, a spring.

As outlined in FIG. 5, a bimetal 34 can serve as a further alternative for controlling the pump 3. It is also possible to use a piezoelectric actuator for this purpose, for example in the form of a bimorph.

According to the invention, therefore, a luminaire is provided, which has a pump 3, wherein the pump can be in particular a diaphragm pump 3 'or a piston pump 3 "The pump can have one or two pumping chambers in both cases Examples of means that can be used for this are: Stirling engine, electric motor, system with coil solenoid, breaker contact, bimetal, piezoelectric actuator. LIST OF REFERENCE NUMBERS

1 housing

2 light source, LED (s)

3 pump

3 'diaphragm pump

3 "piston pump

4 ceiling

5 pumping chamber

5 'second pumping chamber

6 pump cylinders

7 heat sink

8 outlet channel

9 inlet channel

10 outlet opening

11 intake opening

12 membrane

13 movement of the membrane

14 pump chamber ceiling

15 pistons

16 movement of the piston

20 outlet valve

20 'second exhaust valve

21 inlet valve

21 'second inlet valve

22 electric motor

24 magnetic coil

26 submersible magnet

27 valve flaps

30 Stirling engine

31 lower end plate at the hot area

32 upper end plate at the cold area

33 working piston of the Stirling engine 34 bimetal

AR Exterior DE Ceiling E Level

Claims

claims

1. luminaire, in particular recessed luminaire, comprising - a housing (1),

- A within the housing (1) arranged light source (2), and

- A device for generating a through the housing (1) guided gas flow for cooling the light source (2), characterized in that the device comprises a pump (3).

2. Recessed ceiling luminaire according to claim 1, wherein the gas flow passes through a plane (E), which - when the lamp is aligned with respect to the vertical operationally - the housing (1) passes horizontally through the light source (2) or above the light source (2 ) runs.

3. Recessed ceiling light according to claim 1 or 2, wherein the light source comprises at least one LED (2).

4. Recessed ceiling luminaire according to one of the preceding claims, wherein the pump (3) is a positive displacement pump, in particular a piston pump (3 ') or a diaphragm pump (3 ").

5. Recessed ceiling luminaire according to one of the preceding claims, wherein the pump (3)

- A pumping chamber (5), and

- Includes an outlet channel (8) for the gas flow, wherein the outlet channel (8) connects the pumping chamber (5) with the outside space.

6. recessed ceiling light according to claim 5, wherein the pump (3) further comprises an inlet channel (9) for the gas flow, wherein the inlet channel (9) the outer space with the pumping chamber (5). combines.

7. Recessed ceiling light according to claim 6, wherein valves (20, 21) are arranged for controlling the direction of the gas flow at the inlet channel (9) and the outlet channel (10).

8. Recessed ceiling light according to one of claims 5 to 7, wherein the pump (3) further comprises a second pumping chamber (5 ').

9. Recessed ceiling light according to one of the preceding claims, comprising an electric motor (22) for driving the pump (3), wherein preferably a device is provided, with which the rotary movement of the electric motor (22) via a crank drive or an eccentric converted into a linear movement can be.

10. Recessed ceiling light according to one of the preceding claims, comprising a system comprising a magnetic coil (24) and a submersible magnet (26) for driving the pump (3).

11. Recessed ceiling light according to claim 10, wherein the coil (24) with a low-frequency alternating voltage, preferably <20 Hz can be operated.

12. Recessed ceiling light according to one of claims 4 to 11, wherein for controlling the pump (3) a break contact is provided, which preferably opens when the displacement of the pump (3 ') is in an extreme position.

13. Recessed ceiling luminaire according to one of claims 4 to 12, wherein for driving the pump (3), a piezoelectric actuator, such as a bimorph, is provided.

14. Recessed ceiling light according to one of the preceding claims, with a Stirling engine (30) for driving the pump (3).

15. Recessed ceiling light according to claim 14, wherein the Stirling engine is a flat plate Stirling engine.