Speed monitoring system for trains

Abstract

 A speed and distance monitoring system consists of the known ATB system with transmitters 5, receivers in the form of recording coils situated on the train, and an electronic unit for regulating the train's speed, supplemented with additional transmitters 15, 17 and an additional electronic unit. The known transmitter 5 sends an amplitude modulated current with a low-frequency carrier through the rails 9, which is picked up by the recording coils under the train.
The additional transmitters 15, 17 are formed by coils situated next to the rails 9 which send high-frequency signals, which are superimposed on the existing low-frequency signal, and which are also received by the existing recording coils.
The additional electronic unit is connected to the input ports of the existing electronic unit and can separate the additional signals from the signals picked up by the recording coils and deduce information concerning the distance.
When a train passes the additional transmitter 15, monitoring of the braking curve is activated. Monitoring of the braking curve is stopped when the additional transmitter 17 near the semaphore 21 is passed.

Description

BACKGROUND OF THE INVENTION:

Field of the invention

[0001] The invention relates to a speed and distance monitoring system for trains, comprising transmitters that send signals through rails, receivers in the form of recording coils situated on trains and above the rails, and electronic units situated in the trains that are coupled to the recording coils on the train and which process the signals received into, for example, control signals for regulating the speed of the train and/or visual information for the engine driver.

Prior art

[0002] A speed monitoring system is generally known in the form of the ATB system (Automatic Train Influencing System). In this system, an amplitude modulated current with a low-frequency carrier (75 Hz) is conducted through the rails. This current is picked up by recording coils under the train. The upper speed limit is deduced from the modulation frequency. With this system, it was chosen not to use any signal as a code for 40 km/h. Because of this, 40 km/h is the lowest maximum speed the known ATB system can transmit. This means that when red signals are passed at speeds less than 40 km/h the known ATB system cannot intervene.

Summary of the invention

[0003] An objective of the invention is to provide a speed and distance monitoring system of the type described in the preamble that is also effective for speeds less than 40 km/h. To this end, the speed and distance monitoring system according to the invention is characterized in that the speed and distance monitoring system comprises additional transmitters in the form of coils situated next to the rails which send additional signals which can also be received by the recording coils that are already there. Preferably, the additional signals are high-frequency signals (order of magnitude: 1-10 kHz), which when picked up are superimposed on the already existing low-frequency signal. The advantage of the speed and distance monitoring system according to the invention is that use can be made of the recording coils already situated in a train as a result of which no new recorders are necessary in that train. By using higher frequencies the transmitter only needs a limited length, as a result of which information on the distance can also be passed on. By adding monitoring of the distance, the speed and distance monitoring system according to the invention will also be effective for speeds under 40 km/h.

[0004] The coils are preferably coupled to a signal source. The current to the signal lamps or a contact in the safety device which already exists may, for example, function as a signal source.

[0005] An embodiment of the speed and distance monitoring system according to the invention is characterized in that the speed and distance monitoring system comprises an additional electronic unit that can separate the additional signals from the signals picked up by the recording coils. Because the additional signal is of a high frequency, it will not affect the electronic unit already present in the ATB system which already exists and the additional signal can easily be separated from the composite signal.

[0006] A further embodiment of the speed and distance monitoring system according to the invention is characterized in that the additional electronic unit is connected to the input ports of the electronic unit which already exists. Because of this, no extra wiring in the trains is necessary. This is very economical because laying new wiring in trains is very labour intensive and because of that expensive.

[0007] Therefore, on introducing the speed and distance monitoring system according to the invention it will not be necessary to adapt the ATB system which already exists and use is made in a favourable way of a number of components in the existing ATB system.

Brief description of the drawings

[0008] The invention will be elucidated more fully below on the basis of drawings in which an embodiment of the speed and distance monitoring system according to the invention is shown. In this drawing:

Figure 1 shows a train situated on a section of track provided with receivers and an electronic unit of an embodiment of the speed and distance monitoring system according to the invention; and

Figure 2 shows a section of a track provided with transmitters of the speed and distance monitoring system.

Detailed description of the drawings

[0009] In figures 1 and 2 a train 1 and a section of a track 3 are shown which are provided with an embodiment of the speed and distance monitoring system according to the invention. The speed and distance monitoring system consists of the known ATB system with transmitters 5, receivers in the form of recording coils 7 situated on the train which are above the rails 9, and an electronic unit 11 which is coupled to the recording coils 7 for regulating the speed of the train and for visual information (indicators 13) for the engine driver, supplemented with additional transmitters 15, 17 as well as an additional electronic unit 19. The known transmitter 5 sends an amplitude modulated current with a low-frequency carrier (75 Hz) through the rails 9, which is picked up by the recording coils 7 under the train.

[0010] The additional transmitters 15, 17 are formed by coils (turns embedded in plates) situated next to the rails 9 that send additional signals which can also be received by the existing recording coils 7. The additional signals are high-frequency signals in the order of magnitude from 1 - 10 kHz which when picked up by the recording coils are superimposed on the existing low-frequency signal. The coils of the additional transmitters 15, 17 are coupled to the leads of a signal lamp 21.

[0011] The additional electronic unit 19 is connected to the input ports 23 of the existing electronic unit 11 and can separate the additional signals from those picked up by the recording coils 7. Because the additional signal is of a high frequency, it has no effect on the existing electronic unit of the existing ATB system and the signals sent out by these coils are picked up by the recording coils 7 situated in the train as an irrelevant frequency for the ATB system. The additional signal can easily be read at the input port of the electronic unit by the additional electronic unit.

[0012] The additional transmitters 15,17 have different transmitter frequencies and are installed at the semaphore and at a distance before the semaphore next to a rail 9. When the first coil of the additional transmitter 15 is passed by a train, monitoring of the braking curve is activated. When the monitored speed is exceeded the additional electronic unit 19 intervenes by operating an existing brake valve. As an indication to the engine driver a signal is given during the intervention. Monitoring of the braking curve is stopped when the coil of the additional transmitter 17 near the semaphore 21 is passed, at any rate if it does not send a stop signal. If a stop signal is sent then direct intervention takes place immediately.

[0013] Although in the above the invention is explained on the basis of the drawings, it should be noted that the invention is in no way limited to the embodiment shown in the drawings. The invention also extends to all embodiments deviating from the embodiment shown in the drawings within the context defined by the claims.

Claims

1. Speed and distance monitoring system for trains, comprising transmitters that send signals through rails, receivers in the form of recording coils situated on trains and above the rails, and electronic units situated in the trains that are coupled to the recording coils on the train and which process the signals received into, for example, control signals for regulating the speed of the train and/or visual information for the engine driver, characterized in that the speed and distance monitoring system comprises additional transmitters in the form of coils situated next to the rails which send additional signals which can also be received by the existing recording coils.

2. Speed and distance monitoring system according to claim 1, characterized in that the coils are coupled to a power supply.

3. Speed and distance monitoring system according to claim 1 or 2, characterized in that the speed and distance monitoring system comprises an additional electronic unit that can separate the additional signals from the signals picked up by the recording coils.

4. Speed and distance monitoring system according to claim 3, characterized in that the additional electronic unit is connected to the input ports of the existing electronic unit.

Drawing