CZ32751U1 - LED light, especially LED light for chemically aggressive environments - Google Patents

Description

Technical field

This utility model refers to luminaires in a chemically aggressive environment, for example in chemical plants or in areas contaminated by fumes and other exhalations, possibly with air humidity, rain or leaches from the surrounding soil, which produce very aggressive compounds capable of destroying luminaires. The luminaire is particularly suitable as public lighting, for example for tunnels.

BACKGROUND OF THE INVENTION

Luminaires intended for chemically aggressive environments, for example in chemical plants, in areas contaminated by motor vehicle fumes and other exhalations, possibly with air humidity, rain or containing leaches from the surrounding soil, which form very aggressive compounds, shall be made of materials that can withstand they also have good mechanical properties. Stainless steel type ČSN 17240, 17241 (WST 1.4301, AISI 304, DIN X5CrNi 18-10) or more resistant type ČSN 17346 (WST 1.4401, AISI 316, DIN X5CrNiMo 17-12-2) seems to be the most suitable material for these environments, however, suitable plastics are also possible. With the advent of light-emitting diodes (hereinafter referred to as LED source), both stainless steel and plastic luminaires had a relatively fundamental problem with heat dissipation. Approximately 60 to 70% of the power consumption of the LEDs is converted into heat, which must be dissipated into the ambient air, which is a problem especially with the increasing output of LED sources. Unfortunately, stainless steel and plastic conduct heat relatively poorly, and so the design of luminaires with powerful LED lamps made exclusively of stainless steel or plastic was considered impossible. Various designs combined the stainless steel or plastic body of the luminaire with an aluminum radiator, but these solutions have not proved successful due to the rapid corrosion of aluminum in a chemically aggressive environment.

The essence of the technical solution

The presented solution of a LED luminaire suitable also for a chemically aggressive environment with a body made of stainless steel or plastic solves heat dissipation by combining several technical elements enabling to produce an LED luminaire for an aggressive environment with high output and good heat dissipation. The luminaire according to the present invention comprises a stainless steel or plastic body with an upwardly open cabinet space and a flange spaced from the bottom of the cabinet space for accommodating LED modules, a cover glass arranged on the body flange where a gasket is arranged between the body flange and the cover glass , LED modules with LED light sources arranged on a printed circuit board with a metal support layer and arranged at the bottom of the body of the housing, wherein a heat-conducting layer having an area greater than PCB surface area with metal layer. A printed circuit board with a metal layer, the so-called MPCB board (MPCB is the abbreviation for Metal Printed Circuit Board), is used to fix LED sources and provide heat dissipation from them. The metal in these plates is, for example, copper or aluminum, a material with good thermal and electrical conductivity. Particularly preferred is an MPCB board in an arrangement where a direct thermal connection to a metal support material without an insulating intermediate layer normally separating the printed circuit board from the metal support material is formed under the LED source chip that dissipates the heat generated. It is envisaged that one LED module will have more preferably more LED sources than one. Preferably, the luminaire has a heat-conducting layer formed by one heat-conducting pad or a group of heat-conducting pads arranged together. According to another preferred embodiment, the heat-conducting pads are connected to provide heat transfer therebetween. According to yet another preferred embodiment, the heat-conducting layer is arranged at least at least 70%, more preferably at least 80% and still more.

More preferably, at least 90% of the bottom surface of the housing body. According to an even more preferred embodiment, the heat-conducting layer is arranged over at least the entire surface area of the housing body space. According to yet another preferred embodiment, the heat-conducting layer is arranged over the entire surface area of the housing body space and extends to the sides of the housing space.

According to a particularly preferred embodiment, the heat-conducting pad and the heat-dissipating pad are respectively. pads formed of at least one of graphite, copper, aluminum and other heat conducting materials. For the purposes of this application, materials having a thermal conductivity coefficient λ of at least 100W / m.K are particularly preferred as heat-conducting material. Most preferably, the heat conducting pad is formed of graphite which is sufficiently thermally conductive, its thermal conductivity coefficient is greater than 112 W / mK, is soft so that it adheres well enough on one side to the body and on the other to the metal layer of the MPCB board. significantly improves heat transfer and does not require the use of a thermally conductive paste, is inexpensive and easy to machine. The purpose of the heat-transfer layer is to transfer heat from the metal layer of the printed circuit board with the metal layer to the largest possible area of the stainless steel body. The MPCB boards are quite expensive and their area through which the heat released from the individual LED sources is transferred to the heat sink is thus relatively small compared to the surface of the luminaire body. Thus, by means of a heat-conducting layer, the heat from the metal layer of the MPCB board is transferred to a considerably larger body area even if the thermal conductivity of the body material is poor. Stainless steel has a thermal conductivity coefficient of only 0.2 to 0.4 W / m.K, similar to most plastics. With a relatively low wall thickness of the body made of stainless steel or plastic, but thanks to the large body area where the heat from the LED module or modules is transferred via the heat-distribution layer, it can radiate enough heat to cool the power LED sources.

When using heat-conducting pads made of hard material, such as aluminum in particular, which cannot itself connect well enough to adjacent surfaces of the body and / or LED module so that heat transfer at the interface of these parts could be impaired, it is preferable to use a thermally conductive paste that ensures the necessary heat transfer between them.

In order to improve the heat dissipation from the luminaire body to the ambient air, it is advantageous if the luminaire according to the invention has its body blackened, which improves the emission of heat to the environment. For example, in stainless steel, the best results are obtained by using chemical blackening of the body material.

In a preferred embodiment of the luminaire according to the present invention, the body with the cover glass is connected by a "C" type shutter, thereby removing a large number of screws or other clips exerting necessary pressure on the cover glass so that the luminaire is sufficiently sealed by the cover glass pressed against the flange luminaire bodies. The "C" type closure is preferably made of the same material as the luminaire body. The pressure exerted by this closure is the same over the entire length of the luminaire and, moreover, this closure provides protection from gushing water. Thanks to the connection of the body with the cover glass by means of the “C” shutter, the degree of protection up to IP69 can be achieved. However, other cover glass connections to the body are also possible. For the purposes of this application, cover glass means a transparent cover enabling to illuminate a desired space in which the luminaire according to the invention is located by light emitted from the LED modules in the luminaire. The cover glass may be made of glass or a suitable plastic, for example acrylic glass, polycarbonate and other known materials.

Clarification of drawings

The invention will be more readily understood from the following examples and the accompanying drawings in which: FIG

Giant. 1 is a sectional view of the luminaire body with the LED module arranged therein

-2GB 32751 U1

Giant. 2 is a cross-sectional view of the luminaire according to the invention with a cover glass in perspective.

Examples of technical solutions

The present invention will be described by way of examples of specific embodiments and with reference to certain drawings. The accompanying drawings are merely schematic and should not be construed as limited to the embodiments shown. For illustrative purposes, the size of some elements may be exaggerated in the drawings and not necessarily drawn to scale. The dimensions and relative dimensions do not correspond to the actual embodiments of the present invention. The technical solution is not so limited by the exemplary embodiments described herein and the accompanying drawings, but only by the content of the claims.

Furthermore, terms such as top, side, underside and the like in the description and claims are used to specify the body of the invention and refer to a product lying in front of an observer, for example on a table or other flat plate, with the lens facing from table top. These terms are not to be understood in any way to denote the subject matter of the technical solution and its parts at the place of its attachment, ie on the tunnel ceiling, for example, where the cover glass faces downwards to the tunnel floor. It is to be understood that the terms used in the specification and claims are interchangeable in certain circumstances, and that embodiments as described and illustrated herein are capable of operating in other orientations than described or illustrated herein.

An embodiment of a luminaire according to the present invention is shown in Figs. 1 and 2 and comprises a body 1 made of stainless steel sheet having a cabinet space 10 formed therefrom and closed from below to accommodate LED modules 5. The luminaire body 1 is provided a flange 9 spaced from the bottom of the housing 10 for fastening the cover glass 7 and applying the gasket 8. In this embodiment, the flange 9 is formed at the opening edge of the housing 10 of the housing L. in another part of the height of the housing, if the cover glass 7 is appropriately shaped. It is also possible for the rim 9 to be formed directly by the wall forming the housing housing 10, which fits into a gasket 8 arranged, for example, in a gutter of the cover glass 7, whereby the cover glass 7 can be attached to the body 1 by clips, collars and the like cover glass 7 to the body 1 with sufficient sealing of their joint to prevent moisture or pollutants from entering the luminaire.

At the bottom of the cabinet 10 there is arranged a heat-distributing layer 2, formed in FIG. 1 by a group of juxtaposed heat-conducting pads, which are intended to distribute heat over the entire surface area of the cabinet 10 or at least a substantial part thereof. Most preferably graphite is used on these substrates, somewhat inferior to copper or aluminum, but other heat-conducting materials can of course also be used. In another embodiment (not shown), the heat-conducting pad of the heat-conducting layer 2 is formed in one piece. In yet another exemplary embodiment (not shown), the heat-conducting pad of the heat-conducting layer 2 is bent at its ends so that it extends to the sides of the cabinet space 10, thereby further increasing the heat radiation area from the LED module 5.

On the heat-conducting layer 2 there are placed LED modules 5 with printed circuit boards with a metal carrier layer (hereinafter MPCB board) in a special design, with individual LED sources 4. The design of LED module 5 with such an MPCB board is advantageous because the heat from the LED source 4 is directly, ie without an insulating intermediate layer, connected to the metal support layer of the MPCB board, thus significantly reducing the thermal resistance between the semiconductor transition of the individual LED sources 4 of the LED module 5 and this metal layer providing heat dissipation from the LEDs 4 LED module 5 and ensure the best heat dissipation from each LED source 4 located on said MPCB board.

-3 GB 32751 U1

The printed circuit board of the LED module 5 with the LED sources 4 adjoins the optical system 3, which ensures the necessary luminous flux distribution from the individual LED sources 4 according to the desired purpose of the luminaire.

In order to ensure the necessary cooling of the LED sources 4, it is necessary to ensure a good heat transfer between the MPCB board and the heat-conducting pad of the heat-conducting layer 2 as well as between the heat-conducting pad and the luminaire body 1. In the illustrated embodiment, the heat-conducting pad of the heat-conducting layer 2 is made of graphite which is soft and adheres well to the two adjacent surfaces so that a good heat transfer is ensured. In this embodiment, the heat-conducting layer 2 consists of a group of heat-conducting pads which are pressed together to ensure good heat transfer between them. However, such an arrangement of heat-conducting pads is not absolutely necessary, and it is also possible to have a gap between the individual heat-conducting plates. It is only important that the heat distribution mats touch the metal layer of the MPCB board of the LED module 5 with a sufficient area to ensure heat dissipation from each LED module 5.

In another embodiment (not shown), the heat-conducting pads of the heat-conducting layer 2 are formed of aluminum. In order to ensure good heat transfer between the individual heat conducting pads and adjacent surfaces of the body 7 and the individual LED modules 5, a thermally conductive paste is preferably applied between the respective surfaces.

It will be apparent to the skilled person that to ensure good heat transfer it is also necessary to provide sufficient pressure of the MPCB board with LED modules to the luminaire body 1. This can be accomplished by some of the solutions known in the art, and therefore the present technical solution does not address this problem.

In order to ensure the required degree of protection of the luminaire, it is advantageous to use a "C" type closure 6 for this type of luminaire as it removes a large number of screws or other clips exerting necessary pressure on the cover glass 7 and subsequently on the gasket. made of the same material as the body of the luminaire, the applied pressure is the same over its entire length, and moreover, this cap provides protection of the gasket from water jets. Therefore, it is possible to achieve a degree of protection up to IP69 in this way.

PROTECTION REQUIREMENTS

Claims (8)

An LED lamp, in particular an LED lamp for a chemically aggressive environment, characterized in that it comprises - a stainless steel or plastic body (1) provided with an upwardly open housing (10) and a flange (9) spaced from the bottom of the housing (10) for accommodating at least one LED module (5), - a cover glass (7) arranged on the rim (9) of the body (1), wherein a seal (8) is arranged between the rim (9) of the body (1) and the cover glass (7), - at least one LED module (5) with LED light sources (4) arranged on a printed circuit board with a metal support layer, the at least one LED module (5) being arranged at the bottom of the housing (10) of the body (1), and heat - a distributing layer (2) arranged between the metal layer of the printed circuit board with the metal layer of the LED module (5) and the body (1) in contact with them for heat transfer, the area of the heat-distributing layer (2) being larger than is the area of the printed circuit board with the metal layer. LED lamp according to claim 1, characterized in that the heat-distributing layer (2) is 32751 U1 arranged at least at least 70% or more preferably at least 80% or even more preferably at least 90% of the bottom surface of the housing (10) of the body (1). LED lamp according to claim 2, characterized in that the heat-distributing layer (2) is arranged over at least the entire surface of the bottom of the housing (10) of the body (1). LED lamp according to claim 3, characterized in that the heat-distributing layer (2) extends into the sides of the housing space (10) of the body (1). LED lamp according to any one of claims 1 to 4, characterized in that the heat-distributing layer (2) is formed by one heat-conducting pad or a group of heat-conducting pads arranged at the bottom of the housing (10) of the body (1), wherein one side is in contact with the body (1) and the other side is in contact with the metal layer of the printed circuit board with the metal layer of said at least one LED module (5). LED lamp according to claim 5, characterized in that the heat-conducting pad is made of graphite or copper or aluminum or another material with a similar or better thermal conductivity coefficient. LED lamp according to any one of the preceding claims, characterized in that the body (1) is blackened for better heat emission. LED light fixture according to any one of the preceding claims, characterized in that the printed circuit board with the metal layer has, under the LED chip of the source (4), which dissipates the heat generated therefrom, the insulating material of the printed circuit board. a heat-dissipating source (4) with a metallic carrier material.