EP2085692A1 - Electric switch device, in particular signal lights - Google Patents

Abstract

The arrangement has an electronic device (3) e.g. LED, arranged on a printed circuit board (4) that is supported by a housing insert (5) made up of heat conducting material. The housing insert is formed with two-piece of an insertion base (5a) and an insertion head (5b) that supports the printed circuit board. The insert head is formed as hollow body for better heat dissipation, and the insertion base is engaged to a holder by the insert head. The printed circuit board is manufactured from a metal with isolator side applied to the illuminant side.

Description

The invention relates to an electrical circuit arrangement, preferably signal light, for use in potentially explosive areas, with at least one arranged on a printed circuit board electrical component, in particular light source. - The light source is preferably an LED.

Signal lights are commonly used to deliver one or more optical signals that serve to indicate any hazards, peculiarities, etc. For example, signal lights are used for reporting and warning, for example with regard to faults on machines. Just as well, signal lights can also indicate escape routes or point out advertising space.

In a signal lamp according to the structure described above, as described in the DE 102 39 347 A1 is described, a signal tower is used, which is characterized by the cylindrical shape of a printed circuit board with thereon individually controllable luminescent elements. The printed circuit board is a flexible film that can be coated on its outside with a transparent material. This has proven itself in principle.

However, as soon as lamps are generally to be accommodated in a housing for the signal light, the problem of heat dissipation arises in the context of special applications. This applies in particular to those signal lights that are used in potentially explosive areas, ie so-called explosion-proof signal lights. Because such lights regularly have a flameproof enclosure of the housing, so that the removal of heat generated in the housing heat loss from the bulbs is a problem.

Of course, this generally applies to all housing of signal lights, because due to the usually required high light intensity of the bulbs must often be expected with an increased amount of heat loss. This heat loss can lead to an increased temperature in the interior of the housing - whether it is now flameproof or not - compared to the ambient temperature.

As a result of this increased temperature of the housing, the use of the signal light or generally the electrical circuitry in potentially explosive atmospheres may be problematic. Because there is a risk that partial areas of the housing heat up significantly higher than other areas. This effect of the so-called "hot spots" on the device surface is not desirable for signal lights in explosion-proof design.

Because such hot surfaces or "hot spots" can be sources of ignition for the ambient atmosphere in potentially explosive atmospheres. This applies not only to certain gas mixtures or the occurrence of flammable gases, but also to, for example, combustible dusts during the processing of powders. In this context, it should be noted that the smaller the given distance between the associated heat source and the surface, the higher the partial heating by radiation and convection. That is, the occurrence of the described "hot spots" is favored by a small distance between the heat source and the surface and an insufficient heat dissipation of the surface.

Incidentally, resulting from the increased temperature of the housing relative to the ambient temperature further inconvenience, which make negative in particular at high humidity, namely, in the ultimately moisture penetrates into the housing or reflected in this reinforced. This is often the case when the signal light (not) is more in operation. In any case, some significant temperature differences and consequently pressure differences between the signal light and the environment, which can lead to the described negative effects. - Here the invention aims to provide a total remedy.

The invention is based on the technical problem of further developing an electrical circuit arrangement, preferably a signal light, of the structure described at the beginning in such a way that the temperature and thus also the pressure difference between the signal light or an associated housing and the environment is minimized In addition, the occurrence of "hot spots" should be avoided.

To solve this technical problem is in a generic electrical circuitry, preferably a signal light for use in potentially explosive atmospheres, with at least one arranged on a printed circuit board electrical component, in particular bulbs, provided in a housing that the circuit board of a (good) thermally conductive material is made. In the context of the invention, (good) heat-conducting material usually means one which has a (large) thermal conductivity of more than 20 W / (m · K). In particular, even materials with a thermal conductivity of more than 100 W / (m · K) and preferably those with more than 200 W / (m · K) are used primarily. Such values for the thermal conductivity are regularly achieved only by good heat conductors, mainly of metals. This beats the Invention preferably the use of a light metal before, ie such a metal having a density below 5 g / cm ³ .

In this context, metals such as aluminum or aluminum alloys have proved favorable as materials for the printed circuit board. In principle, however, copper and alloys such as brass can also be used, which are, however, not (more) a matter of light metals in the above sense, which is anyway only an option.

In order to insulate the lamp and its contacts from the metal circuit board, the metal circuit board in question is equipped on the illuminant side with an applied insulation. In addition, a copper cladding may be applied to the circuit board, which provides the necessary electrical connection points and connections for the light source on the circuit board and provides the prerequisite for an (automated) soldering process for mounting the light source on the circuit board. In fact, the illuminant is in fact advantageously a light-emitting diode (LED), in particular one in SMD technology (SMD = surfacemounted device), ie an SMD LED.

In other words, the light-emitting diode in question is applied to the surface of the printed circuit board and contacted here, and, for example, no conductor legs are passed through the printed circuit board. For the contacting of the lamp and its control ensures the applied Kupferkaschierung. The insulation which is also provided on the upper side of the printed circuit board produces the necessary electrical resistance.

In this case, the structure is usually designed so that the printed circuit board made of metal or aluminum, the first side of the light source insulation or insulation layer and then carries the aforementioned copper lamination, which in turn then picks up the light source mounted on the surface. On its side facing away from the light source or surface, the printed circuit board is advantageously connected to a housing insert or is supported by this housing insert,

The fact that the housing insert is advantageously also made of a thermally conductive material, it is ensured that any resulting in the light generation by means of the light source heat loss is discharged directly via the metallic circuit board to the likewise metallic housing use by heat conduction. Of course, the same applies to the case where, instead of the light source, another electrical or electronic component is arranged on the metallic circuit board in question, for example a loudspeaker which may act as a signal loudspeaker. In any case, according to the invention, the waste heat inevitably emitted by the electrical or electronic component in question is forwarded directly via the metallic printed circuit board to the housing insert and finally to the housing.

This results in a total of rapid heat dissipation and effective heat distribution from the heat source or the electrical / electronic component over a large surface. Thus, the emergence of the previously discussed "hot spots" is already basically prevented.

Because the housing insert has a relatively large surface area, it already acts as a temperature sink. The heat conduction is improved in the event that the case in question is connected to the housing. Because usually the housing is also made for the most part of metal, so that the heat over the housing insert in this Case additionally delivered to the housing by heat conduction and distributed from here by heat radiation or convection heat in conjunction with the ambient air to the outside.

In this case, one will work with materials or metals for the printed circuit board, the housing insert and the housing, which have comparable or identical thermal conductivities, in order to ensure an unimpeded heat flow. Here, aluminum has proven to be favorable as a common material.

In this case, the heat flow is supported or promoted by heat conduction between the metallic printed circuit board and the likewise metallic housing insert by providing a thermal paste between the printed circuit board and the housing insert for a high thermal conductivity. In any case, the circuit board is thermally connected to the housing insert and this in turn thermally connected to the housing, so that an uninterrupted heat flow from the lamp via the circuit board, the housing insert is finally observed to the housing. In this case, an increasing surface enlargement takes place, so that heat can be released from each individual component advantageously by heat radiation and convection to the ambient atmosphere, and increasingly from the circuit board to the housing.

It has proven useful if the housing insert is formed essentially in two parts with an insert foot and an insert head supporting the circuit board. The housing insert is usually connected via the insert foot to the housing (thermal). The insert head is usually designed as a hollow body. Here, an angular shape in the sense of a triangle, quadrilateral, pentagon, preferably a hexagon, etc. has proven to be favorable. Because Such polygons provide with their side surfaces advantageous mounting surfaces for multiple circuit boards available.

In fact, the insert head is usually designed as a hexagonal hollow prism, thus has an approximately hollow cylindrical shape in the interior and a hexagonal design on its outer surface. As a result, in each case one printed circuit board with associated lighting means can be accommodated on each of the six side surfaces, so that the lighting means as a whole sweep over a light emission angle of 360 ° without any problems. Because the LEDs used have beam angles of generally 30 ° to 90 ° or even more. D. h., The plurality of printed circuit boards are usually arranged spatially so that an all-round light emission is achieved, d. H. one that covers an angle of 360 °, which is of particular importance to most signal lights.

Finally, it is provided for better heat dissipation, that the hollow or hollow cylindrical running application head is placed on a web of the insert foot and the insert foot engages with this web in the insert head. Thereby, the insert head can be easily mounted with the Einsatzfuß, namely, for example, such that the insert head has grooves in which the web engages the insert head when the insert head is plugged onto the Einsatzfuß. In addition, a total of a large surface through the hollow design of the insert head is available and incidentally, the heat from the insert head is easily forwarded to the Einsatzfuß out.

The result is an electrical circuit arrangement or in particular a signal light available, which is particularly predestined by the described and particularly sophisticated heat dissipation for use in potentially explosive atmospheres. Because the inside of the Housing unavoidably resulting heat loss due to the electrical / electronic components or the light source is dissipated quickly and discharged through a generally enlarging surface in the direction of heat flow to the environment. As a result, not only the emergence of the already described "hot spots" is prevented in the result, but the temperature of the housing can be reduced to values that are not significantly above the ambient temperature, for example, do not exceed values of about 60 ° C. In most cases, the temperature of the housing is even lower, for example below 50 ° C.

This reduced temperature difference of the housing compared to the ambient temperature and the lack of "hot spots" prevents any surrounding and ignitable gases or dusts in the environment from exploding. Thus, the described circuit arrangement for use in potentially explosive atmospheres is particularly predestined. In addition, the reduced temperature difference of the housing compared to the environment causes the formation of moisture inside or the penetration of moisture is largely prevented by pressure differences in the interior. This increases the life and reliability of the electrical circuitry as a whole.

The invention achieves this in the core in that the electrical or electronic component or light source on the circuit board of the heat-conductive material, in particular the metallic circuit board, is added. The printed circuit board in turn forwards the resulting heat to the housing, which is also very heat-conductive or metallic. Here are the main benefits.

Fig. 1

die erfindungsgemäße elektrische Schaltungsanordnung in Gestalt einer Signalleuchte schematisch,

Fig. 2

den Gehäuseeinsatz entsprechend der Fig. 1 in einer Seitenansicht und

Fig. 3

eine Aufsicht auf den Gehäuseeinsatz nach Fig. 2 aus Richtung X.

In the following the invention will be explained in more detail with reference to a drawing showing only one exemplary embodiment; show it:

Fig. 1

the electrical circuit arrangement according to the invention in the form of a signal light schematically,

Fig. 2

the housing insert according to the Fig. 1 in a side view and

Fig. 3

a top view of the housing insert Fig. 2 from direction X.

In the figures, an electrical switching arrangement in the form of a signal light is shown, which has a housing 1. In the interior of the housing 1, there is an electrical respectively electronic component 3 arranged on a printed circuit board 4. In the exemplary embodiment, the component 3 in question is designed as a luminous means 3. The housing 1 is configured substantially in two parts with a housing foot 1a and a more or less transparent housing head 1b. The transparent housing head 1b ensures that the light emitted by the luminous means 3 in the interior of the housing 1 can perform the required signal or warning function, as has already been described in the introduction. That is, in the electrical circuit arrangement is an electrical signal circuit arrangement and here preferably to the signal light shown in detail in the figures.

In this case, the light source 3 is arranged on the circuit board 4 in detail. According to the invention, the printed circuit board 4 is made of a thermally conductive material, ie made of such a material, which has a thermal conductivity of more than 20 W / (m · K). Usually, it is a metallic circuit board 4, preferably one of aluminum, that is to say an aluminum circuit board 4.

As a light source 3, several spatially arranged LEDs 3 are used, and advantageously LED's in SMD technology. In this case, the lighting means 3 are arranged circular in comparison to a central axis A of the housing 1, with respect to which the housing 1 is rotationally symmetrical. In this way, the light emitted by the LEDs or light sources 3 is emitted in all spatial directions, so that an all-round light emission is ensured in connection with the transparent housing head 1b of the housing 1.

The detailed structure is best recognized by the in Fig. 3 enlarged sectional illustration shown. From this it can be seen first of all that the circuit board 4 is supported by a housing insert 5 and is thermally connected thereto, as will be explained in more detail below. The circuit board 4 itself is connected with its surface facing away from the bulb 3 with the housing insert in question 5, in the present case with the interposition of a thermal paste 6 or a comparable material or fluid to reduce the heat transfer resistance between the circuit board 4 and the housing insert 5. Instead of or in addition to Thermal paste 6, the circuit board 4 on its housing insert 5 facing surface can also be equipped with a heat conduction promoting copper coating or other coating. This is not shown.

The construction of the surface of the circuit board 4 facing the luminous means 3 is based on the Fig. 3 The circuit board 4 initially has on the illuminant side or on the surface facing the luminous means 3 an applied insulation layer 7, which provides the necessary electrical insulation of supply lines to the luminous means 3 and of the luminous means 3 as such in comparison to the circuit board 4 provides. The insulating layer 7 may be used as a lacquer, powder coating, plastic coating, etc. be executed. Subsequently, in the direction of the luminous means 3, there is a copper coating 8 or generally a conductive coating 8, which provides the necessary supply lines and connecting points for the respective luminous means 3.

In this case, the luminous means 3 is applied directly to this conductivity or copper coating 8. In addition to the copper coating or conductive coating 8 applied Lötstopplack 9 optionally ensures the automated soldering process that a perfect solder joint of the lamp 3 is achieved with the connection points or conductors on the part of the conductivity or copper coating 8. This, of course, is only one option.

The decisive factor is the fact that any loss of heat associated with the light generation of the light source 3 is transmitted directly from the metallic circuit board 4 by heat conduction via the thermal compound 6 to the housing insert 5. Since the housing insert 5 shown in the Fig. 1 and 2 already has a relatively large surface, the heat loss in question can be easily radiated over a large surface or is transmitted via convection to the surrounding atmosphere or outside air. In this case, the heat flow is further optimized by the fact that the housing insert 5 is thermally connected to the housing 1, for example screwed thereto. This results in a further enlargement of the heat-emitting surface, namely in the form of the housing made of metal foot 1a. For reasons of a uniform heat flow, the housing insert 5 as well as the housing 1 will generally be made of aluminum.

On the basis of a comparative analysis of the Fig. 1 and 2 it can be seen that the housing insert 5 in two parts with an insert foot 5a and a Insertion head 5b is formed, which carries the respective printed circuit board 4 and the plurality of printed circuit boards 4. In the context of the exemplary embodiment and not restricting the insert head 5b is formed in cross-section as a polygon with respective side surfaces 10, each carrying a printed circuit board 4. In fact, the respective circuit board 4 is screwed by means of a screw 11 with the respective side surface 10 of the insert head 5b. In each case above and below the screw 11 there is a light source. 3

The printed circuit boards 4 are in each case flat with the interposition of the thermal paste 6 on the side surfaces 10, wherein the lamps 3 advantageously have a vertical arrangement in the direction of the axis A, which is not mandatory.

Based on Fig. 3 can be seen further that the insert head 5b is formed as a hollow body, in which the insert foot 5a engages. For this purpose, the insert foot 5a on the head side has a web 12 which engages in associated grooves 13 of the insert head 5b or the insert head 5b is attached to the web 12 in question of the insert foot 5a, which facilitates assembly. In addition, this already makes the required thermal or thermal contact between the insert head 5b and the insert foot 5a available.

The lamps 3 or LED's can be configured in one color or different colors. Of course, white light LEDs are also included in the invention. By a possible color choice in the LED's in the sense of yellow, red, green and / or blue can be dispensed to color the housing head 1 b or the transparency at this point. Nevertheless, the signal function can be flanked with a corresponding color or even several colors as desired.

Furthermore, it is within the scope of the invention, if necessary, to additionally cool the respective metallic printed circuit board 4 and / or the housing insert 5 and / or the housing 1 as a whole. This can be done with the help of Peltier elements. - The fact that the individual circuit boards 4 are contacted by means of plugs 14, the structure is particularly simple. Because the housing foot 5a of the housing insert 5 is not only used for heat conduction and heat dissipation, but in addition to bundle leads 15 for the bulbs 3 and lead. After attaching the insert head 5b make the plug 14 the required electrical connection.

Claims (10)

Electrical circuit arrangement, in particular electrical signal circuit arrangement, preferably signal light, for use in potentially explosive areas, with at least one on a printed circuit board (4) arranged electrical component (3), in particular light source (3), characterized in that the circuit board (4) made of a thermally conductive material. Electrical circuit arrangement according to Claim 1, characterized in that the printed circuit board (4) has a thermal conductivity of more than 20 W / (m · K), in particular more than 100 W / (m · K), preferably more than 100 W / (m • K) and more preferably more than 200 W / (m • K). Electrical circuit arrangement according to Claim 1 or 2, characterized in that the printed circuit board (4) is produced from a metal with insulation (7) applied to the luminaire side. Electrical circuit arrangement according to claim 3, characterized in that it is the metal for the production of the printed circuit board (4) is a light metal having a density below 5 g / cm ³ . Electrical circuit arrangement according to one of claims 1 to 4, characterized in that the printed circuit board (4) is thermally connected to a housing (1). Electrical circuit arrangement according to one of claims 1 to 5, characterized in that the printed circuit board (4) by a housing insert (5) is supported. Electrical circuit arrangement according to Claim 6, characterized in that the housing insert (5) is connected to the housing (1). Electrical circuit arrangement according to claim 6 or 7, characterized in that the housing insert (5) substantially in two parts with an insert foot (5a) and the circuit board (4) carrying insert head (5b) is formed. Electrical circuit arrangement according to claim 8, characterized in that the insert head (5b) is designed for better heat dissipation as a hollow body, in which the insert foot (5a) engages for its support. Electrical circuit arrangement according to one of claims 1 to 9, characterized in that a plurality of printed circuit boards (4) are realized with associated components (3) having an overall circular and spatial arrangement in comparison to an axis (A).

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