EP3686489B1 - Lamp with cooling support sheet - Google Patents

Description

The invention relates to a lamp according to the preamble of claim 1.

From the US 7 198 387 B1 a lamp is known which uses LEDs (light emitting diodes) as light sources. In order to dissipate the waste heat generated in the LEDs, the entire housing is designed in the manner of a heat sink, with cooling fins.

An LED unit can be found in the data sheet, which was available on January 9, 2019 at the Internet address https://www.vossloh-schwabe.com/uploads/tx sbdownloader / LED-Line-SMD-Kit 3R-G DE.pdf known, each comprising a plurality of LEDs. The LED unit is assigned an optical unit which influences the light emitted by the LEDs.

Tub lights for fluorescent tubes are also known, with reference to the example US 7 083 308 B2 is referred.

From the WO 2005/073629 A1 it is known that the housing is designed like a trough, wherein it extends along a longitudinal axis, wherein it has a U-shaped cross-sectional shape with a base and two U-legs in a central region with respect to the longitudinal axis, the heat sink with a constant Cross-sectional shape extends along the longitudinal axis, wherein it has a central section which is arranged transversely to the longitudinal axis between two lateral sections, the central section forming a substantially flat contact surface facing away from the housing, the LED unit being fastened to the contact surface is, wherein the lateral sections each have at least one first web which is aligned essentially perpendicular to the contact surface, wherein it is formed in one piece with the central section, wherein the first webs each form a first free end of the heat sink which points towards the housing, the U-legs of the housing each having a second free end which points towards the heat sink, wherein it rests against an associated first free end, the LED unit and / or the at least one optical unit is encompassed in a U-shape by the two lateral sections and the central section. The housing and the heat sink are designed as extruded profiles, which can only be produced economically in large numbers.

From the DE 10 2017 203 203 A1 a lamp is known which comprises an equipment carrier which is designed as a bent sheet metal part. On the side edges pointing transversely to the longitudinal direction, the device carrier has bends which serve for stiffening.

One advantage of the present invention is that the lamp according to the invention can be used as a replacement for the known tub lights, which have essentially the same structural dimensions as a known tub light. The lamp according to the invention is extremely simple. In addition to the electronic and lighting components available on the market, it only includes two other components, namely the housing and the heat sink. These two parts are designed to be particularly material-saving and thus inexpensive. The heat sink can be attached to the housing in a particularly simple manner, preferably solely by means of two screws. Nevertheless, the entire luminaire is inherently stable. In particular, no deformation of the heat sink due to its own weight can be observed.

According to the invention it is provided that the two lateral sections each comprise a second web which is oriented perpendicular to the contact surface, it being arranged between the associated first web and the contact surface, the second web directly adjoining the contact surface. The second web is preferably formed in one piece with the first web and the central section. It also serves to increase the bending stiffness of the heat sink. The second web also ensures that the lateral sections of the heat sink encompass the LED and the optics unit in a U-shape, with the first free ends of the first webs pointing towards the housing at the same time.

According to the invention, it is provided that the first and the associated second web are connected to one another in one piece via a connecting section, so that they together form a U-shape. In this way, the heat sink can be implemented as a bent sheet metal part in a cost-effective manner. In the corners of said U-shape, the sheet metal is preferably bent along a line parallel to the longitudinal axis. The heat sink is preferably made of aluminum. It is preferably formed by several bends from a flat plate of constant thickness. It is also conceivable to manufacture the heat sink using an extrusion process. The connecting section is preferably arranged approximately in one plane with a light-emitting surface of the optics unit, and it is most preferably set back somewhat.

According to the invention, it is provided that the U-shaped cross-sectional shape of the housing is covered with an end plate at both ends of the housing pointing away from one another in the direction of the longitudinal axis, the heat sink being attached exclusively to the two end plates. The end plates are preferably formed integrally with the remainder of the housing. The housing can be made by bending deformation from a flat plate of constant thickness, it being provided with a bend on each of its two edges facing away from each other transversely to the longitudinal axis, which forms a first U-leg, with it being on both of its edges with respect to the longitudinal axis ends pointing away from one another are each provided with a bend which forms an end plate, the end plates adjoining both U-legs essentially without a gap. The end plates are preferably firmly connected to the U-legs by means of blind rivets. For this purpose, bent-over fastening tabs are provided in one piece on the end plates. The housing is preferably made of sheet metal. It exists preferably made of steel, which is most preferably painted. The housing can also be made of plastic by injection molding.

The housing is therefore designed similar to the housing of a known tub light. The unit consisting of heat sink, LED unit and optics unit can be attached to the housing in a similar way to the cover of a known diffuser light. Because of the high rigidity of the structural unit mentioned, only very few fastening elements are required for this, preferably only two.

The housing preferably has a constant cross-sectional shape in the central area. The first web serves primarily to increase the second-degree moment of area of the heat sink with respect to the longitudinal axis. The entire heat sink is preferably designed in one piece. The optics unit can be composed of several optics sub-units which are assigned to different sections of the LED unit. The parts of the optics unit are preferably attached to the LED unit and / or the heat sink. The LED unit can be composed of several assemblies, it preferably comprising a single assembly. The assemblies mentioned are preferably attached directly to the heat sink. The U-legs are preferably aligned perpendicular to the base. The lateral sections of the heat sink are preferably designed mirror-symmetrically to one another. The middle section of the heat sink is preferably designed in the form of a flat plate with a constant thickness. The heat sink is preferably made from sheet metal. The first and / or the second free end preferably run parallel to the longitudinal axis. The first free ends preferably lie laterally against the respectively assigned second free end. The first free ends of the heat sink and the second free ends of the first U-legs are preferably flat in the area of the abutment mentioned. The at least one optics unit is preferably detachably connected to the LED unit, the parts mentioned being most preferably screwed together with the heat sink.

Advantageous developments and improvements of the invention are specified in the dependent claims.

It can be provided that the cross-sectional shape of the cooling body has an essentially constant thickness everywhere.

It can be provided that the second free ends of the U-legs are each provided with a bead, on which an associated first free end of the cooling body rests in such a way that the surfaces of the cooling body and the first U-leg facing the environment are in there an escape are arranged. This prevents dirt and / or moisture from collecting at the corresponding joint.

It can be provided that the heat sink is attached to the housing exclusively at its two ends pointing away from one another with respect to the longitudinal axis. The heat sink is preferably screwed to the housing there. Fastening tabs which are bent over at right angles are preferably provided in one piece on the heat sink, which are directly adjacent to the central section. A separate contact washer is preferably arranged between the aforementioned fastening tabs and the housing, which securely establishes an electrically conductive contact between the housing and the heat sink. The contact disk is preferably penetrated by a screw bolt, which also penetrates the fastening tab.

It can be provided that the housing, together with the heat sink, encloses a substantially closed cavity, a power supply unit to which the LED unit is electrically connected being arranged in the cavity. The power supply unit is preferably attached to the first base of the housing. The power supply unit is preferably designed in the manner of a constant current driver. The LEDs, which are preferably connected in series, are consequently all supplied with a fixed, predetermined current, the voltage at the individual LEDs being set accordingly.

It can be provided that the heat sink is made of aluminum, the housing being made of steel or plastic. A heat sink made of aluminum dissipates the waste heat from the LEDs particularly well. The proposed materials for the housing are particularly inexpensive.

It can be provided that the LED unit comprises a circuit board on which a plurality of separate LEDs are distributed, the circuit board being attached to the middle section of the heat sink, the optics unit each having a funnel-like reflector in the area of the LEDs which is covered by a transparent or translucent material. Said material is preferably a plastic, most preferably polymethyl methacrylate (PMMA; also called acrylic glass). The circuit board and / or the optics unit is preferably screwed to the heat sink. The LEDs are preferably arranged in a grid-like manner on the board.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or on their own, without departing from the scope of the present invention.

Fig. 1

eine Explosionsansicht einer erfindungsgemäßen Leuchte; und

Fig. 2

einen Querschnitt der Leuchte nach Fig. 1.

The invention is explained in more detail below with reference to the accompanying drawings. It shows:

Fig. 1

an exploded view of a lamp according to the invention; and

Fig. 2

a cross-section of the lamp Fig. 1 .

Fig. 1 shows an exploded view of a lamp 10 according to the invention. The lamp 10 is shown in a position in which the housing 40 is down. This position is advantageous during the assembly of the lamp 10. In operation, the housing 40 is typically arranged at the top, it being fastened, for example, to the basic structure of an assembly workstation in order to illuminate a work area.

In the present case, the housing 40 is designed in the form of a bent sheet metal part which is made from sheet steel. But it can also be injection molded from plastic. It is also conceivable that the housing has a base body made of an extruded aluminum profile, the end plates 45 being designed as separate parts which are firmly connected to the base body.

In all of the cases mentioned, the housing 40 is designed like a trough. In a central region it extends with a constant cross-sectional shape along a longitudinal axis 11. The central region takes up almost the entire length of the housing 40. At the two ends of the housing 40 pointing away from one another in the direction of the longitudinal axis, an end plate 45 is provided, which is oriented perpendicular to the longitudinal axis 11. Said cross-sectional shape of the housing 40 is U-shaped with a base (No. 41 in Fig. 2 ) and two U-legs (No. 42 in Fig. 2 ) educated. The housing 40 is preferably designed as a bent sheet metal part. The blank is accordingly a flat plate of constant thickness, the border of which is cut to size in a common manner, for example by means of punching or laser cutting. The U-legs and the end plate 45 are each formed by an associated 90 ° bend. The end plates 45 are preferably each firmly connected to the two U-legs by means of blind rivets 47. For this purpose, a bent fastening tab 46 is preferably provided in one piece on the end plate 45.

A power supply unit 60 is fastened, in particular screwed, to the base of the U-shape. The power supply unit 60 can be connected to the 230V alternating current network via the connection cable 61 which is led to the outside. It is preferably designed as a constant current driver, which generates a direct current suitable for operating the LEDs 51 with a predetermined current strength from the alternating mains voltage. Reference should be made to the protective conductor 62, via which all metallic parts of the lamp 10 that can be touched from the outside are electrically connected to the protective conductor of the mains supply.

A heat sink 20 is also provided, which consists of aluminum, and is preferably designed as a bent sheet metal part. The heat sink 20 forms a flat contact surface 23 which extends parallel to the longitudinal axis 11. An LED unit 50 rests directly on the contact surface 23 facing away from the housing 40, so that the waste heat generated there in the LEDs 51 (light emmitting diodes) can be given off to the environment with a low thermal resistance. The LED unit 50 is covered by an optical unit 70. The optics unit 70 is preferably designed in such a way that the point-like light emitted by the LEDs 51 is uniformly distributed in the room without the users of the room being dazzled by the very bright LEDs 51 when they look directly at the luminaire 10.

The optics unit 70 is fastened together with the LED unit 50 to the heat sink 20 by means of screw bolts 73. In the present case, the optics unit 70 comprises two optics subunits 72 which are identical to one another. Depending on the length of the luminaire 10, a suitable number of optics subunits 72 is selected. In the present case, the LED unit 50 comprises a single circuit board 52, which is provided with a multiplicity of LEDs 51 arranged in a grid-like manner. The LEDs are preferably connected in series, any mixed forms of series and parallel connection being conceivable. The board is provided with two connection sockets 54. One connection socket 54 is electrically connected to the power supply unit 60 via the first connecting cable 53. In the present case, the other connection socket 54 is short-circuited with a second connection cable 55. There further identically designed LED units can be connected to one opposite Fig. 1 to realize longer luminaires. At the two ends pointing away from one another in the direction of the longitudinal axis 11, the optical units 70 are closed at the end with separate end plates 75.

The heat sink 20 is fixedly connected to the housing 40 exclusively at its ends pointing away from one another in the direction of the longitudinal axis 11. A fastening tab 28 is provided there in one piece on the heat sink 20, by means of which it is screwed to an associated end plate 45 of the housing 40. A contact disk 29 is located between the fastening tab 28 and the end plate 45 arranged, via which a reliable electrical connection between housing 40 and heat sink 20 is established. Aside from this screw connection 30, the heat sink rests exclusively on the housing 40 in a frictionally engaged manner, it even being possible within the scope of the present invention to dispense with a locking engagement which is difficult to produce.

Fig. 2 shows a cross section of the lamp 10 according to Fig. 1 . The heat sink 20 comprises a central section 21, which is arranged transversely to the longitudinal axis between two lateral sections 22. The middle section 21 is defined by the flat contact surface 23 to which the LED unit 50 and the optics unit 70 are attached. The contact surface 23 points away from the housing 40 so that the light from the LEDs 51 is emitted to the outside. The two lateral sections 22 serve to stiffen the heat sink 20 against bending deformation. They are therefore made significantly higher than the central section 21 perpendicular to the contact surface 23. As a result, the lateral sections 22 have a considerably higher second-degree moment of area than the central section 21. In addition, the two lateral sections 22 and the contact surface hold the LED -Unit 50 and the optics unit in a U-shape, so that overall a compact and rigid structural unit results, which can be attached to the housing 40 very easily and quickly. Despite the only two fastening points at the end, no noticeable bending deformation due to the weight of the assembly can be detected on this assembly.

The lateral sections 22 each comprise a first and a second web 25; 26, which are aligned perpendicular to the contact surface 23. The two webs 25; 26 are integrally connected to one another via a connecting section 27, which is aligned essentially parallel to the contact surface 23, so that a U-shape results. At the end facing away from the connecting section 27, the second web 26 is connected in one piece to the middle section 21, so that it is directly opposite the optics unit 70 laterally. At the end facing away from the connecting section 27, the first web 25 has a first free end 24 which rests from the outside against a second free end 43 of an associated U-leg 42 of the base body 40. The second free end 43 is provided with a bead 44 or provided a recess, so that the outer surfaces of heat sink 20 and housing 40 are arranged in alignment in the area of mutual contact.

The optics unit 70 comprises a funnel-like reflector 71 for each LED 51. A plate-like cover 76 made of transparent or translucent material is also provided.

Reference number

10

lamp

11

Longitudinal axis

12th

cavity

20th

Heat sink

21

middle section

22nd

side section

23

Contact surface

24

first free end

25th

first bridge

26th

second bridge

27

Connection section

28

Fastening tab

29

Contact washer

30th

Bolt

40

casing

41

Base

42

U-leg

43

second free end

44

Bead

45

End plate

46

Fastening tab

47

Blind rivet

50

LED unit

51

LED

52

circuit board

53

first connection cable

54

Connection socket

55

second connection cable

60

Power supply unit

61

Connection cable

62

Protective conductor

70

Optics unit

71

reflector

72

Optics sub-unit

73

Bolt

75

End plate

76

cover

Claims (7)

1. Lamp (10) having an LED unit (50), at least one optics unit (70), a heatsink (20) and a housing (40), wherein the LED unit (50) comprises a plurality of separate LEDs (51), wherein the LED unit is attached to the heatsink (20) in a manner such that waste heat from the LEDs (51) may be dissipated to the environment at least indirectly via the heatsink (20), wherein the optics unit (70) is connected to the LED unit (50) in a manner such that it influences the light that is emittable by the LEDs (51), wherein the housing (40) is formed in the manner of a trough, wherein it extends along a longitudinal axis (11), wherein it has a U-shaped cross-sectional shape having a base (41) and two U-legs (42) in a region that is central with respect to the longitudinal axis (11), wherein the heatsink (20) extends with a constant cross-sectional shape along the longitudinal axis (11), wherein the heatsink has a central section (21) arranged transversely to the longitudinal axis between two lateral sections (22), wherein the central section (21) forms a substantially planar support surface (23) facing away from the housing (40), wherein the LED unit (50) is attached to the support surface (23), wherein the lateral sections (22) each have at least one first web (25) that is oriented substantially perpendicularly to the support surface, wherein said web is formed in one piece with the central section (21), wherein the first webs (25) each form a first free end (24) of the heatsink (20) that points toward the housing (40), wherein the U-legs (42) of the housing each have a second free end (43) pointing towards the heatsink (20), wherein the second free end rests against an associated first free end (24), wherein the LED unit (50) and/or the at least one optics unit (70) is surrounded in the shape of a U by the two lateral sections (22) and the central section (21), characterized in that the two lateral sections (22) each surround a second web (26) oriented perpendicularly to the support surface (23), wherein the second web is arranged between the associated first web (25) and the support surface (23), wherein the second web (26) immediately adjoins the support surface (23), the first and the associated second web (25; 26) are connected to one another in one piece via a connection section (27) so that they together form a U shape, wherein the U-shaped cross-sectional shape of the housing (40) is covered by an end plate (45) on both ends of the housing (40) that face away from one another in the direction of the longitudinal axis (11), wherein the heatsink (20) is attached exclusively to the two end plates (45).
2. Lamp according to Claim 1,
   wherein the cross-sectional shape of the heatsink (20) has a substantially constant thickness everywhere.
3. Lamp according to either of the preceding claims,
   wherein the second free ends (43) of the U-legs (42) are in each case provided with a bead (44), against which in each case an associated first free end (24) of the heatsink (20) rests in a manner such that the surfaces of the heatsink (20) and the first U-leg (42) that are facing the environment are arranged there so as to be aligned.
4. Lamp according to one of the preceding claims,
   wherein the heatsink (20) is attached exclusively at its two ends facing away from one another with respect to the longitudinal axis (11) to the housing (40).
5. Lamp according to one of the preceding claims,
   wherein the housing (40) encloses together with the heatsink (20) a substantially closed cavity (12), wherein a power supply unit (60) to which the LED unit (50) is electrically connected is arranged in the cavity (12).
6. Lamp according to one of the preceding claims,
   wherein the heatsink (20) consists of aluminium, wherein the housing (40) consists of steel or of plastic.
7. Lamp according to one of the preceding claims,
   wherein the LED unit (50) comprises a printed circuit board (52) on which a multiplicity of separate LEDs (51) are arranged in a distributed fashion, wherein the printed circuit board (52) is attached to the central section of the heatsink (20), wherein the optics unit (70) has, in the region of the LEDs (51), in each case a funnel-type reflector (71) that is covered by a transparent or translucent material.

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