EP2119614B1 - Signalling unit with LED redundancy - Google Patents

Abstract

The signaling unit has a light source including a glow filament and a control circuit. A switching unit detects failure of a filament lamp current in the control circuit, using a current relay in the control circuit or alternatively by an electronic circuit. A quasi point LED unit is utilized as a backup light source having a directional characteristic corresponding to the former light source and a preset signal color. The backup source or an outlet for light beams from the backup source is arranged in a main axis of the former light source.

Description

The present invention relates to a signaling unit. Such signaling units are used especially in rail and road traffic as light signals.

There are a lot of light signals in traffic systems, especially in the railway networks in operation, which are equipped with incandescent lamps as light sources. In Switzerland alone, more than 30,000 light sources are expected to be. Signaling technology in traffic is based on actuators that control the signal lamps with precisely defined operating parameters. In addition, the light sources are measured by measuring predetermined electrical parameters, e.g. the magnitude of the flowing current in the lamp circuit, indirectly monitored for a correct light output. In signaling technology, the assumption is that current flow through an incandescent lamp is synonymous with the emission of light. Incandescent lamps have a limited life and usually fail with a burn through / melting of the filament with the subsequent interruption of the circuit. As a result, the intended function of the visual display, e.g. a railway driving authorization information (signal term) from. Such failures are critical, especially with stop commands. It is spoken depending on the function of operation inhibition and / or then from operational hazards. As a result, an active use of maintenance personnel for the replacement of the defective light source is briefly required for the elimination of this condition.

If the operator wants to avoid these short-term maintenance interventions for the exchange of signals, the solution is to replace the incandescent lamp with another technology. In signaling technology, this is already practiced with the LED technology for original equipment, such as in the DE 199 47 688 A1 disclosed. But the Functionality of many operating in the lamp actuator parts with their interlocking interface require incandescent lamp substitutes, which, however, are usually relatively expensive. For simple solutions on the light source side would require extensive adjustments to the (monitoring) systems.

Primarily, however, it is necessary to achieve and ensure the required very low residual error probability in the sense of safety (safety) by means of the monitoring devices or other measures.

A conversion to low-maintenance light sources is therefore very expensive and causes high costs and would have to be made during the conversions in the signal boxes overnight. In addition, after such operations on a facility prior to the start of the use of the upgraded functions, a safety inspection and an official operating license are generally required. The effort is very large. Elaborate conversions allow today very short rest intervals in the transport networks of only a few hours, usually after midnight. Economic criteria speak against it.

It is now the object of the invention that in case of failure of a light bulb, a method and a device take over that function which allows further operation and the maintenance, that is the lamp change in the signal, can be postponed up to several days. The conventional immediate use for the maintenance is thus eliminated. This also greatly reduces the risks of physical injury to maintenance staff.

Before the solution according to the invention is presented, the present state of affairs should be summarized here again below. A failure of an incandescent lamp by Wendelbruch is by the associated Detected control part and a corresponding error message generated by the control in the interlocking (system). This error message registered in the interlocking is now processed in the dispatching level of the control technology by the dispatcher. In other words, this means that the on-call service will be called in to replace the failed light source. At the same time, if necessary and as far as possible, the routes (routes) for the trains are adjusted in order to bypass the failed signal point and thus to avoid operational obstacles. However, this measure can reduce the line capacity accordingly, which is undesirable on the network operator side, but absolutely essential for safety reasons.

When using double-filament lamps in a signal system designed for this purpose, a device switches automatically to the secondary eddy by means of a device if the main filament breaks. In this case, however, due to the position of the auxiliary coil outside the focal point only a reduced light intensity in the main axis of the signal is achieved and the emission characteristic also changes according to the focal deviation. Electrically speaking, based on the monitoring circuit, however, there are no changes in the circuit parameters due to the helical switching, with the exception of the transient switching of transient artifacts. It should be emphasized here that filament lamps for signaling purposes (and that is the majority of many tracks) can not be replaced by double filament lamps. The reason for this are the different operating data of the incandescent lamps and thus the functional characteristics of the control units installed for single-filament lamps, which are not designed for controlling the two lamp filaments.

According to the invention, it is now provided to operate a LED replacement light source in the lamp signal circuit parallel to the incandescent filament. This source can be synchronous are controlled simultaneously with the control of the lamp or this replacement light source is on cold redundancy and is switched at the time of helix failure in the circuit and takes over the triggered by the control part current flow in the control circuit, the light output of the signal. Such a light emission substitute takes over in the event of failure of a single-filament or at most two-filament incandescent lamp a suitable substitution of the light source and thereby avoids interruptions of the functionality of the signal and thus in the course of operation. As a result, the timing of the repair of the signal much better planning than usual.

In a first variant, the inventive approach assumes that the standard light source has, for example, a nominal power consumption of a typical signal lamp of 20 watts. By contrast, the substitution light source, together with its drive device, has a significantly lower power consumption. As a result, however, the light source monitoring dimensioned in terms of incandescent lamp characteristics in the associated control part is not able to recognize it as being functional on the basis of the monitored electrical parameters in accordance with the lower power consumption and thus the smaller current of the LED emitter.

However, this actually faulty behavior can now, if necessary, be taken into account anew by the use of corresponding automatic methods of error processing for the formation of route bypasses at the faulty signal point by deactivating this processing. Deactivation is allowed because the reliability of the LED light sources is very high, especially when used as cold redundancy.

By a very simple form of the circuit and an LED arrangement as light source with high reliability and a temporally low duration of use is a monitoring of the function of the LED array is not mandatory, because the intended functionality can be assumed with very high probability.

If the above approach to reliability is not sufficient for very high security requirements, specific additional criteria are still switched in the monitoring, which allow selective depending on the occurrence of decisions of error feedback by the monitoring device. Table of principles with exemplary values No Primary light source Light source redundant function 1 single filament
20 watts nominal; Operation by day with approx. 17.5 Watts Cold LED
Power 1 to 3 watts in operation The LED is activated according to the principle of filament switching when the main filament fails in the double filament lamp. The possible effect of switching to monitoring is determined by the following relations: a) The power consumption of the redundant light source is small compared to the filament of the incandescent lamp. b) The light output of the redundant light source is comparable to the filament lamp. 2 single filament
see above Hot LED power <2 watts in operation Both light sources (incandescent lamp and LED) are activated at the same time.
Condition for operation:
The power consumption of the redundant light source is often smaller compared to the incandescent lamp. Eg <2W. If this specification is not met, adjustments in the monitoring circuit of the signal circuit are required and the selectivity of the error detection decreases as a result. 3 Double thread lamp
20 watts nom.
Operation by day with approx. 17.5 Watts Cold LED power 1 to 3 watts in operation The LED is switched on as described under point 1 in the lamp circuit, but we are only active when both filaments of the light bulb are broken.

Figur 1

in schematischer Darstellung eine erste Signalanordnung mit einer Glühfadenlampe und LED- Ersatzlichtquelle;

Figur 2

in schematischer Darstellung eine zweite Signalanordnung mit einer Glühfadenlampe und eine über einen Lichtwellenleiter gekoppelte LED- Ersatzlichtquelle;

Figur 3

ein Prinzipschaltbild für einen Signalkreis einer Einfadenlampe mit Stromrelais; und

Figur 4

ein Prinzipschaltbild für einen Signalkreis einer Doppelfadenlampe mit Stromrelais.

The figures shown below illustrate some embodiments. Showing:

FIG. 1

a schematic representation of a first signal arrangement with a filament lamp and LED replacement light source;

FIG. 2

a schematic representation of a second signal arrangement with an incandescent filament lamp and coupled via an optical waveguide LED replacement light source;

FIG. 3

a schematic diagram of a signal circuit of a filament lamp with current relay; and

FIG. 4

a block diagram for a signal circuit of a double filament lamp with current relay.

The Figures 1 and 2 each schematically show a light signal, in which in addition to the light bulb, an LED unit is provided to replace the bulb in the event of burning their filament. In FIG. 1 the LED unit is arranged directly behind the light bulb on the main light axis; in FIG. 2 The light of the LED unit is fed via a light guide behind the light bulb in the main light axis. In both embodiments, between the incandescent lamp and the LED unit ( Fig. 1 ) resp. arranged an infrared filter to the light exit of the light guide to at least greatly attenuate a thermal feedback of the light bulb to the LED unit or the light guide.

Since no reflectors (mirrors) are permissible for a path signal (prevention of phantom light), the luminous flux via an exit lens on the signal is given only by the solid angle detected by the exit lens. In other words, this means that a large part of the solid angle is black and thus absorbs the light radiation. Modern LED units with quasi punctiform light sources therefore achieve luminous fluxes of up to 100 lumens and more, which easily reach the luminosity of the incandescent lamp used in the signal at significantly lower power consumption.

The current latest generation of LEDs now has a luminous efficacy of up to 100 lumens / watt. The incandescent lamp signals radiate in the required and common in the railway safety technology execution (avoidance of phantom light) only a relatively low luminous flux. This is calculated from the active solid angle (sterradiant) and the transmission of the color filter with a light source with white A 2856 ° K. For the signal color red, the 10 lumens are then emitted to the front. From these points of view, the luminous flux defined above must then be assessed.

The whistle of the inventive solution is therefore seen to incorporate in signals with incandescent light source a redundant replacement light source in LED technology. The incandescent lamp is left unchanged in the defective state in the signal housing and is used in a suitable manner as an optical function part in the beam path of the then shining LED light source.

The LED light source radiates directly into the main axis of the beam path from the glass bulb of the incandescent lamp directed forwardly against the light exit opening of the signal or uses a collimator for processing the radiation characteristics and / or a light guide for the supply of light to the appropriate point in the main axis. In this case, the glass bulb of the incandescent lamp is used as a kind of lens, which throws the light in a suitable manner forward on the front lens. It is thereby achieved at least approximately the same effect as is present through the helix in the focal point of the optics.

This is achieved by the inventive solution a significant relief in several points. On the one hand, no changes have to be made in the control of the lamp power on the side of the control panel, and the conventional light bulbs can be replaced by those with a redundant LED unit. The design required for this purpose therefore only concerns the incandescent insert module and requires - if at all - only minimal adjustments to the signal. On the other hand, the maintenance staff does not have to disengage immediately in the event of failure of the light bulb to restore the route safety as quickly as possible, but because of the high reliability of the LED technology can be assumed with an extremely high probability that the LED unit lights up instead of the bulb. Of course, a failure of the light bulb triggers a service order on the part of the interlocking or the control technology, However, this is executable with much greater deadline.

The FIGS. 3 and 4 now each show a schematic diagram for a light bulb insert with redundant LED unit; once for a light bulb with only one filament ( Fig. 3 ) and once for a light bulb with a double thread ( Fig. 4 ).

Claims (6)

1. Signalling unit comprising:

   a) a light source with an incandescent filament and a control circuit,

   b) a switching facility for detecting failure of a filament lamp current in the control circuit, preferably using a current relay in the control circuit of the light source or alternatively by an electronic circuit, characterised by

   c) a quasi-punctiform LED unit used as a backup light source with a radiation characteristic corresponding to the light source and the respective signal colour.
2. Signalling unit according to claim 1, wherein the backup light source or the outlet for light beams from the backup source is arranged in the main axis of the light source in the radiation direction of the light beams in the main axis behind the incandescent filament.
3. Signalling unit according to claim 1 or 2, wherein the radiation characteristic of the LED unit corresponding to the light source can be produced directly by the dome of the LED or by placing a collimator in front.
4. Signalling unit according to one of claims 1 to 3,
   wherein a thermal protection of the LED unit is provided by maintaining a clearance (air gap) or using a fibre optic light guide or an IR filter or a desired combination of these measures.
5. Signalling unit according to one of claims 1 to 4,
   wherein the outcoupling of the light from the LED unit is radiated forwards in the direction of the main axis or near to the glass bulb in the main axis.
6. Signalling unit according to one of claims 1 to 5, wherein the glass bulb of the light source serves as a collimator.

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