JPH0474225B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a low-frequency track circuit for detecting the presence of a train on a track, in which signal information different from conventional track circuit information is superimposed and transmitted to the rail. This relates to a low frequency orbit circuit that can be used.

[Prior art and its problems]

Various types of track circuits have been known for detecting trains in automatic railway signal sections, but a typical method includes a first track circuit called a low-frequency track circuit.
There is a method as outlined in the figure. In FIG. 1, 1 is a rail on which a train runs, 2 and 3 are traffic lights, 4 and 5 are impedance bonds, 6 is a track voltage transmission transformer, 7 is a track relay, and 8 is a train. The rail 1 is electrically insulated at the traffic lights 2 and 3,
At the track power transmission end of the signal 2, the 50Hz or 60Hz output of the track voltage power transmission transformer 6 is transmitted to the rail 1 via the impedance bond 4, and at the track power reception end of the signal 3, the power transmission voltage is received via the impedance bond 5. , which operates the track relay 7. When the train 8 goes further than the location shown in the diagram and enters between the traffic lights 2 and 3, the rail 1 is short-circuited by the wheels, so the input voltage to the track relay 7 disappears and the system is restored. Then, the presence of the train 8 on the line is detected.

With such a track circuit, the number of pieces of information that can be transmitted via the rails is about two pieces of information even if the polarity of the transmission signal is reversed on the power transmission side. Therefore, when attempting to transmit additional information between traffic signals, modulation is applied to a frequency band that does not affect existing track relays, such as audio frequency (AF), according to the type of information, and the low frequency track relay is There is a method of superimposing the information on the circuit, or a method of transmitting power by directly modulating the power transmission voltage of the low frequency track circuit according to the type of information to be superimposed to the extent that it does not affect the track relay. In the former case, a modulator/transmitter that modulates and transmits the audio frequency and a receiver demodulator with high reception and demodulation functions are required separately, and the transmission distance is shorter than that of the low frequency orbit circuit, so A repeater may be required. In addition, with the latter method, the modulation depth for direct modulation has a limit of about 20%, and increasing the modulation depth beyond that will cause the track relay to vibrate, eventually leading to malfunction.
Therefore, the transmission level of the superimposed information is limited by the modulation factor, and it may be difficult to ensure the S/N ratio of the superimposed information due to disturbance noise or the like.

[Means for solving problems]

The present invention has been made in view of the above points, and modulates the output of the low frequency orbit circuit by switching the modulation frequency depending on the type of information to be superimposed, and selects this modulation frequency for reception on the power receiving side. By removing voltage fluctuations due to modulation,
The transmission distance of the superimposed information is the same as that of the existing low frequency orbit circuit, and moreover, it provides transmission of the superimposed information with a good S/N ratio.

〔Example〕

The present invention will be described in detail below based on the illustrated embodiments. FIG. 2 is a configuration diagram showing an example of a track circuit to which the present invention is applied. In FIG. 2, 1 to 8 are the same as in FIG. 1, 9 is a modulator, 10 is a receiving demodulator, 11 is a removal device, and 12 is a waveform of a modulated low frequency signal rail voltage.

Next, the operation of such a configuration will be explained. First, at the transmitting end of the signal 2, the output from the track voltage power transmission transformer 6 is amplitude-modulated by the modulator 9 according to the type of information superimposed, and the impedance bond 4
to the rail 1, the voltage of which is like the modulated low frequency signal rail voltage waveform 12. The type of information to be superimposed is switched by changing the modulation frequency. At the signal 3 at the power receiving end, the voltage transmitted via the impedance bond 15 is received, and the voltage fluctuation due to amplitude modulation is removed or reduced to the extent that it has no effect by the removal device 11, and the voltage is input to the track relay 7. Therefore, the track relay 7 operates normally. On the other hand, the reception demodulator 10 receives the superimposed information. That is, if the modulator 9 modulates at the frequency fn corresponding to the information type Fn, the reception demodulator 10
The frequency of fn is selected and determined, and the information type Fn is output. Note that if the applied low frequency orbit circuit has good characteristics and stable information transmission is possible even at a low modulation degree, the removal device 11 is not necessary.

FIG. 3 shows an embodiment in which superimposed information is transmitted to a running train. In the figure, 1 to 11 are the same as in FIG. 1 or 2, and 13 is a receiving antenna;
4 is an on-board receiving demodulator, and 15 is a train wheel.
In FIG. 3, in the ground equipment, modulation information is flowing to the rail 1 as described above, so after the train passes the power receiving end, the rail 1 is short-circuited by the wheels 15, and a short-circuit current flows. This short-circuit current generates an induced voltage in the on-board receiving antenna 13, which is received and demodulated by the on-board receiving demodulator 14, thereby making it possible to transmit information from the ground to the on-board vehicle.

〔Effect of the invention〕

As explained in the above embodiments, the low frequency track circuit according to the present invention enables information transmission between traffic lights on the ground or from the ground to a vehicle. In particular, by adding a removal device that removes or reduces the influence on existing track relays, stable information transmission can be provided. From this, when adding display types of above-ground signals such as high-speed signals, there is no need to install cables between all signals, and by adding simple equipment, it is possible to connect between above-ground signals or This makes it possible to transmit information from the ground to the vehicle, and has many advantages, including significant cost savings.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of a conventional low frequency track circuit, Fig. 2 is a block diagram showing an embodiment of a low frequency track circuit according to the present invention, and Fig. 3 is a block diagram showing an example of a low frequency track circuit according to the present invention. FIG. 2 is a configuration diagram showing an example. 1...Rail, 2,3...Traffic light, 4,5...
Impedance bond, 6...Track voltage transmission transformer, 7...Track relay, 8...Train, 9...Modulator, 10...Reception demodulator, 11...Removal device,
12... Waveform of modulated low frequency signal rail voltage, 13... Receiving antenna, 14... Onboard receiving demodulator, 15... Wheels.

Claims (1)

[Claims] 1. Modulator 9, reception demodulator 10, and removal device 1
1, the modulator 9 is inserted after the track voltage power transmission transformer 6 in order to superimpose new information, and the modulator 9 is inserted after the track voltage power transmission transformer 6 to generate a low frequency signal for train detection transmitted from the track power transmission end. The receiving demodulator 10 receives and demodulates the modulated frequency at the receiving end of the track, and the removing device 11 is inserted before the track relay 7 to remove the influence of the modulating voltage. Low frequency orbit circuit.