Light signal for controlling a means of transportation

Abstract

The present invention is therefore based on the objective of providing a light signal whose light points can always be reliably perceived, even in winter weather conditions. This objective is achieved according to the invention by a light signal (2) for controlling a means of transport, in particular a rail vehicle, comprising: a) at least one luminous point defining a volume in which a light source (4) associated with this luminous point is arranged; b) a windscreen (8) limiting the volume in the direction of emission and transparent to the light of the light source; c) a heating element (6, 18) arranged in the volume and / or in the windscreen (8); and d) a control circuit (12) for supplying the luminous point (4) and the heating element (6, 18) with electrical power, wherein a constant current source (32) is provided for supplying the heating element, which provides a predefinable current for the circuit of the heating element (6, 18).

Description

[0001] The present invention relates to a light signal for controlling a means of transport, in particular a rail vehicle.

[0002] Light signals are widely used to control traffic flow, such as in rail and road traffic.

[0003] Depending on their location, traffic lights, for example in mountains and Nordic countries, are often exposed to very long periods of winter weather. Wet snow, in particular, can obscure the light of a signal due to snow hanging from the barge and / or snow directly on the windshield. In the worst-case scenario, this can even lead to a vehicle passing a red-light railway signal, with the associated safety hazards.

[0004] Very often, the individual light points are designed so that the light source of each light point is located in a relatively well-sealed volume. Incandescent lamps, which typically have power consumption of 10 to 50 watts in railway applications, generate a comparatively large amount of heat, which is usually sufficient to warm the front lens of the light point from the inside. This makes it difficult for windblown wet snow to adhere to the outside of the lens. Furthermore, the heat rising from the lens also warms the protective cover above the light point against precipitation, thus virtually eliminating the risk of snow overhanging the lens and obscuring the light point.

[0005] For reasons of longer lifespan and low maintenance, more and more lighting points, especially in railway signals, are being equipped with LEDs, which require significantly less electrical power to achieve the same brightness. Furthermore, the heat generated by an LED is also considerably lower than that of a traditional incandescent bulb.

[0006] Thus, the problem of sufficient visibility of light points in winter weather conditions, especially blown-in wet snow, is once again virulent, as the heat generated by the LED light source may no longer be sufficient to keep the windshield and the visor free of snow.

[0007] Precisely because traffic signals in railway and road areas are exposed to the elements, and deposits of snow, ice, or frost on the surface of the signal lenses can impair visibility, separate signal heaters are used to reduce these safety-relevant impairments. These heaters, in the form of electric heating elements (ohmic resistors), are installed, for example, in and / or on the surface or inside the housing of a signal. These heaters are powered by an electrical supply. A particular challenge here is determining the number of individual light points that need to be heated at a signal location, as well as the distance between the electrical supply and the signal location.In railway signals, all light points are necessary to determine the signal aspect. Therefore, either all light points must be heated, or none at all, as otherwise the signal aspect could be misinterpreted. For this reason, the signal heaters of individual light points are connected in series, so that the failure of a single heater affects all light points and thus prevents any misinterpretation that could compromise signal safety.

[0008] Connecting resistive loads in series presents a challenge for the design of the signaling system's power supply. This is especially true given that signal locations are often far from the actual power supply (railway technology: the technical room can be several kilometers away from the signal location). This also makes the conductor resistance, particularly the ohmic resistance of the supply line, relevant as a voltage divider.

[0009] This problem has previously been addressed in railway systems by providing a conventional power supply in the technical room, using a transformer with different voltage ratings and additional series resistors. This allows the necessary voltage to be set for each signal location, especially if a variable resistor is also used. This type of power supply requires individual consideration of each location, the number of light points, and the length of the existing cable to the signal location.

[0010] The present invention is therefore based on the objective of providing a light signal whose light points can always be reliably perceived with simple measures, even in winter weather conditions.

[0011] The problem is solved according to the invention by a light signal for controlling a means of transport, in particular a rail vehicle, comprising: a) at least one luminous point defining a volume in which a light source associated with that luminous point is arranged; b) a front panel limiting the volume in the direction of emission and transparent to the light of the light source; c) a heating element arranged in the volume and / or in the front panel; and d) a control circuit for supplying the luminous point and the heating element with electrical power, wherein a constant current source is provided for supplying the heating element, which provides a predefinable current for the circuit of the heating element.

[0012] In this way, it is possible to keep the windshield and / or the lens of the light largely free of snow, thus guaranteeing the visibility of the light even in adverse weather conditions. The control circuit can also include communication devices that can receive control signals to switch on the heating element in response to prevailing weather conditions. This allows the heating element to be switched on selectively, for example, only during snowfall or specific wet snow conditions. By supplying the electrical power to the series-connected heating element(s) of several light points from a single power source, it is ensured that sufficient current always flows through the heating element(s) to adequately heat the light point.

[0013] Further advantageous embodiments of the present invention can be found in the remaining dependent claims.

[0014] Advantageous embodiments of the present invention are explained in more detail with reference to the drawing. The figure shows a schematic view of a light signal 2 with an LED light point 4 and a front lens 8 equipped with wire filaments 6. The light signal 2 rests on a signal mast 10 and further comprises a control unit 12 for switching on the LED light point 4. The control unit 12 receives its control commands from an interlocking card 26 in an interlocking 30 via corresponding supply lines 14, which also supply the energy for operating the LED light point 4 and its accompanying heating element. Furthermore, with appropriate configuration, the control unit 12 can also send corresponding status and / or diagnostic messages back to the interlocking via the supply lines 14. The interlocking can therefore be designed as a central unit in an interlocking building or as a decentralized, individual logic unit directly on the track near the light signal 2.

[0015] The control unit 12 further has supply lines 16 to a heating cartridge 18 and supply lines 20 to the wire filaments 6 integrated in the windshield 8. All of the aforementioned components are located in a signal box suspended from the signal mast 10. Approaching the light signal 2, a driver sees the LED light point 4, which is projected through the windshield 8, which may also include lens-shaped elements for focusing the light illuminated by the LED light point 4, and is surrounded by a signal plate 24. A protective cover 26 is provided to protect the windshield 8 from direct precipitation from above.

[0016] By means of the wire filaments 6 and the heating cartridge 18, the windshield can now be heated sufficiently that wet snow blown onto the windshield 8 by the wind cannot harden there, but is melted away or does not accumulate there in the first place. In addition, the heat radiated outwards from the windshield 8 also heats the underside of the guard 26, which then causes snow, especially snow extending beyond the guard 26, to fall off. Thus, the visibility of the light signal 2 is ensured even in very adverse winter weather conditions.

[0017] The energy required for the wire filaments 8 and the heating cartridge 18 can be supplied in various ways. Besides a signal box-side supply via a constant current source 32, the light signal 2 could also be connected to a constant current source independent of the signal box, such as the often-present public power grid. Alternatively, battery operation with associated solar cells or similar could be provided to supply the constant current source for the heating cartridge 18 and the wire filaments 8.

[0018] The present invention thus modifies the previously common method of supplying power to signal heaters via a voltage source. According to the present invention, a constant current source is used instead of a voltage supply. This makes it possible for the constant current source to induce a defined current in the heating system, ensuring that the same current, and therefore the same power, is always delivered to each individual light point, regardless of the number of light points or their distance from the signal location (cable length - resistance). Because light point heaters were already being built with electrical resistors in the 1970s, the prevailing approach has been stuck in the same patterns of thinking, leading to continued use of this method.The present invention now breaks with this thought structure, and by using modern electronic power sources, the implementation of the supply of signal heaters can be simplified and made more effective.

Claims

1. Light signal (2) for controlling a means of transport, in particular a rail vehicle, comprising: a) at least one luminous point defining a volume in which a light source (4) associated with this luminous point is arranged; b) a front glass (8) limiting the volume in the direction of emission and transparent to the light of the light source, c) a heating element (6, 18) arranged in the volume and / or in the front glass (8); and d) a control circuit (12) for supplying the luminous point (4) and the heating element (6, 18) with electrical power, wherein a constant current source (32) is provided for supplying the heating element, which provides a predefinable current for the circuit of the heating element (6, 16).

2. Light signal (2) according to claim 1, characterized by the fact that At least two light points are provided, with the heating elements of the at least two light points connected in series.

3. Light signal (2) according to claim 1 or 2, characterized by the fact that the control circuit (12) is set independently of the light source used to a power consumption that provides a current for the operation of an incandescent lamp with a predefinable luminous intensity, whereby, due to a possibly lower power consumption by the light source (4) compared to the incandescent lamp, the excess power can be consumed in the heating element (6, 18).

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