Electricity: measuring and testing – Electrical speed measuring – Including 'event' sensing means
Patent
1995-12-20
1998-05-26
O'Shea, Sandra L.
Electricity: measuring and testing
Electrical speed measuring
Including 'event' sensing means
340936, G01P 366, G08G 101
Patent
active
057571783
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method for reliably determining the speed of railway vehicles, particularly those with bogies, as the vehicles pass a measuring zone. In the measuring zone, axles of the railway vehicle pass two sensors spaced a known distance apart.
Such a method fore determining the speed of railway vehicles is known in conjunction with a device for controlling a train stop in railway systems from DE 31 06 432 C2. There, the determination of the speed of railway vehicles is carried out using two pulse generators which are arranged a given distance apart along a line and can be influenced by the rail vehicles, the respectively measured average travelling speed being obtained from the relationship V=s/t, where V indicates the speed, s the distance between the pulse generators and t the time which the individual wheelsets require from passing the first pulse generator to passing the second pulse generator.
The known device and the method applied there for determining the speed of railway vehicles has proved generally successful in practice. However, difficulties can arise if the vehicles are equipped with electromagnetic rail brakes or eddy-current brakes, because these brakes can influence the event indicators arranged on the line in an undesired way. The handling of vehicles with such brakes in axle-counting systems and systems for determining the speed of running-over railway vehicles is problematic because the brakes do not necessarily act in the same way on the event indicators used for the detecting of wheelsets and for the determining of advancing speeds. For example, it may be the case that such a brake is detected by a first event indicator as a running-over event, but not by a second indicator. It is also possible for one event indicator to detect one running-over event and the other to detect two running-over events when a vehicle with a brake passes. The existence of such event indications not caused by wheel axles had until now the result that the advancing speed could be reliably determined only in each case for the first axle of such a bogie. For all the remaining axles of a vehicle or set of vehicles which pass the measuring zone, speed determination is no longer possible if, due to unsymmetrical influencing of the two event indicators, there is no longer any fixed assignment between the respectively detected event indications and the vehicle axles causing them.
It would be desirable to determine the advancing speed of the remaining axles of a vehicle or a set of vehicles, in order to be informed in this way of the particular advancing speed of this set of vehicles. Specifically, if the latter were to accelerate, there would possibly be the need for automatic braking before a signal, or else a speed restriction. The problems involving the disturbing influence of electromagnetic rail brakes on axle counters is known (DE 38 42 882 A1). At present there are still no reliable measures for suppressing the disturbing influence of electromagnetic brakes or eddy-current brakes on a rail-side event indicators.
SUMMARY OF THE INVENTION
The present invention reliably discriminates between signals corresponding to passing axles of the railway vehicle and spurious signals that may be caused by disturbances such as the activation of electromagnetic brakes or eddy-current brakes. According to the present invention, it is possible to blank out the effects of any disturbances on rail-side sensors for determining the speed of the axles of railway vehicles, in particular those with bogies.
The present invention achieves this objective by establishing time windows, initiated by the passage and detection of a first axle, within which a following axle must pass and be detected in order to be used to calculate the speed of the passing vehicle. Spurious signals detected outside of these time windows, say from electromagnetic brakes, are disregarded.
The time window commences when the first axle passes over the second sensor and closes after a time by which the secon
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patent: 4514690 (1985-04-01), Miller, Jr. et al.
patent: 5331276 (1994-07-01), Polvani et al.
Luehrs Peter
Wilms Gerhard
O'Shea Sandra L.
Phillips Roger
Siemens Aktiengesellschaft
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