Device for automatically locating a railway vehicle

Details Device for automatically locating a railway vehicle Device for automatically locating a railway vehicle

1999-09-20

2001-01-02

Le, Mark T. (Department: 3617)

Railway switches and signals

Train-position indication

Miniature model

C246S194000

Utility Patent

active

06168119

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a device for self-location of a track-guided vehicle.
BACKGROUND INFORMATION
The present invention concerns a device according to the definition of the species of Patent German Patent No. 11 76 698, describes a device for self-location of a traction vehicle in conjunction with a train protection system with linear signal transmission between train and track. This traction vehicle is inductively coupled via coupler coils to a line conductor installed in the track; information relevant for control of the vehicle is supplied to the vehicle from a remote control station via the line conductor. The coupler coils are arranged at a 90° angle to one another and at a 45° angle to the line conductor loop. This coil arrangement makes it possible to send and receive frequency-modulated messages to and from a central station including when passing intersection points. Furthermore, this coil arrangement makes it easy to determine exactly when the vehicle with its antennas passed a line conductor intersection point. When leaving one line conductor section and entering the following line conductor section, the phase angle of the received voltages of the two coupler coils changes by 180°, with this phase shift being different for the two antennas, depending on location. Although the antenna pointed in the direction of travel is already coupled to the line conductor of the following section and receives signals from there with a 180° phase rotation in comparison with the signals received previously, the received voltage that can be picked up at the output of the antenna oriented in the direction opposite the direction of travel still has the original phase angle. The two phase angles can thus be compared with one another; it is deduced from the transiently simultaneous presence of received voltages in phase opposition that an intersection point has been passed. However, not only is the phase angle of the two received voltages evaluated to detect a line conductor intersection point, but also its amplitude is used, i.e., the amplitudes of two received voltages must have a certain minimum level for an intersection point to be detected. Transient transmission interference that cannot be interpreted as driving past an intersection point is characterized by the absence of such a minimum level.
In addition to transmission systems with receiving antennas in a crossed or offset arrangement on the vehicle, there are those with only a single antenna, as described in German Patent Application No. 19 08 400, or with two coupled receiving antennas arranged side by side on the forward and return conductors of a line conductor. With the help of these receiving antennas, it has so far been impossible to detect intersection points by phase discrimination. Although here again, the phase angle of the received voltages changes in passing a line conductor intersection point, the received voltages undergo a reversal of polarity at the same time. Thus, no reference phase is available to evaluate this phase shift, so that only the drop in level could be used in the past to detect an intersection point with such antenna arrangements.
SUMMARY OF THE INVENTION
The object of the present invention is to improve upon the existing devices for self-location of a track guided vehicle so that unambiguous detection of line conductor intersection points is possible even for vehicles with a single antenna or side-by-side receiving antennas coupled to the forward and return conductors of a line conductor by evaluating the phase angle of the received voltage. With a device according to the present invention, a drop in level caused by a line conductor intersection point can be differentiated unambiguously from a drop in level caused by transmission interference, loose contacts and the like.
As a consequence of the vehicle device retaining the instantaneously prevailing phase angle for a certain period of time when there is a drop in level, it is possible once the received voltage rises again to compare the phase angle of the received voltage prevailing then with the reference phase angle thus retained, to arrive at a decision regarding whether the drop in level was caused by passing a line conductor intersection point or by interference.


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