AU600157B2

AU600157B2 - Track circuit

Info

Publication number: AU600157B2
Application number: AU20472/88A
Authority: AU
Inventors: Gilbert Alt
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-12-16
Filing date: 1988-08-05
Publication date: 1990-08-02
Anticipated expiration: 2008-08-05
Also published as: GB8827837D0; NZ225744A; GB2213972A; AR244149A1; AU2047288A; FR2624819A1; FR2624819B1; GB2213972B

Description

I I I I I I I I I I I I I I I I I I.61 1.4

K__

I

CUMONEATHOF AUSTRALIA 6 0 0 '1 5 F710 PATENTS ACT 1952-69 COMPLETE SPEC IFICATION*s

(ORIGINAL)

Class mnt, Class Application Number: Lodged: 'CZomplete Specification Lodged: Accepted: Published: PtIrorty; a,

I

L

77 Related Art: N~ame of Applicant: A.4dress of Applicant Actual Inventor: Address for Service GILBERT ALT 79 rue Pierre Joigneaux, Bois-Colombes 92270, France- GILBERT ALT EDWDS WATERS SONS, 50 QUEEN STREET, MELBOURNE, AUSTRALIA, 3000.

Complete Speeriflcation for the invention entitled: TRACK CIRCUIT The following statement Is a full description of this Invention, lncludling the best method of performing It known to

I,

la The present invention is regarding a track circuit for railway track consisting of two r'ls of a railway block and comprising a generator of alternating current connected with an extremity of the track circuit to produce in the circuit an alternating signal of specific frequency a'd a receiver operating a track relay on the extremity herein called a track circuit of the type specified. Such track circuits are presently widely used to ensure the safety of trains running on railway tracks. They enable to know whether a train is on a specific section of the track called "track circuit" when a short circuit is produced between two rails by one or several axles.

2 bThe presaent--nvntion-4-re Ca rLUuiL for railway track consisting of two railsf a railway block and comprising a generator of alternati g current connected with an extremity of the track circ t to produce in the circuit an alternating signal of s cific frequency and a receiver operating a track rela on the extremity. Such track circuits are prese y widely used to ensure the safety of trains running n railway tracks. They enable to know whether a in is on a specific section of the track called "track rcuit" when a short circuit is produced between two raia -by one o- several axles.

In the case of rail circuits using a welded track, Sthe length limitation of track circuits is obtained by creating an electric filter (or "electric joint") at each ,1o end of the track circuit, consisting of a short track 0 15 section, self-inductance coils and capacitors, enabling to S. limit the propagation of the electric signal of the said track circuit to the section of the track between these two filters whilst the track circuits enclosing the said track 4 L, circuit are supplied by currents of different frequencies.

o *0 o 20 Generally such track circuits are satisfactory as long as the shunt consisting of the axles of a train has an 4* a electric resistance which is sufficiently lIw and that it comprises at least two axles sufficiently distant to ensure the continuity of occupancy of two adjoining track circuits.

Yet, improvements made in track circuits of this type in order to increase their length by using either low supply frequencies or capacitors placed between the rails show a shuntage discontinuity between two adjoining track circuits and a short length working (engine running light, line inspection car, a wagon by itself) may not be detected if it is in this critical area.

We have attempted to improve this by superposing a short length circuit track at a high frequency on this critical area, but this solution is costly, complicated and difficult to use when we want to get the repetition of signals on board the engines.

o 1

MEN.-

I ii 3 The present invention proposes to remedy these drawbacks and relates to a track circuit of the type specified in the introduction and which is characterized by the fact that the filter placed near the transmitter consists of a capacitor, or a capacitance connected between both rails of a short track section such track section being limited on both ends of the capacitor, or capacitance by a dipole and the transmitter of the said track circuit and the receiver of the track circuit adjoining this transmitter are connected to the terminals of the capacitor or capacitance and by the fact that the filter placed near the receiver also consists of a capacitor, or capacitance connected between both rails of a short track section limited at each end of this capacitor, or capacitance by a dipole and that 1the receiver of the said track circuit and the transmitter of the adjoining track circuit are connected to the terminals of the said cap aitor or capacitance in such a way that a single axle placed on this capacitor or capacitance short circuits every time simultaneously the transmitter of 2the said track circuit and the receiver of the adjoining track circuit or the receiver of the said track circuit and the transmitter of the adjoining track circuit whilst the dipoles enable to control the propagation of the currents of the said track circuit and of the enclosing track circuits.

A25- As rreast .Qf this invention, we thus have a lonq track 2b circuit without any insulating gaskets and having no bad detection zone at each of its extremities. Al g a first construction method, the dipoles consistin of the elements marked 6, 7, 8 and 9 of the filters or ectric gaskets represented on diagram 1 only compr e three series and parallel connected components, a capacitor and two inductance coils or two cap itors and an inductance coil.

This arrangement enables ipoles 6 and 8 to obtain a very low impedance (a few illiohms) for the frequency of the currents of trac circuits A and C and a high impedance (several ohm for the frequency of the current of track circuit Dipoles 7 and 9 have a very low impedance for /Z-u*g^eriy-e-f--ee--er-e-f t-r a c k c i--e i-tB-ad h-i gh-- 3a There is provided according to the present invenCion a track circuit of the type specified, including a rail track section limited at both ends by a set of three dipoles each connected between both rails and spaced a short distance from each other, a ce,.tral dipole of each set including a capacitive element and adapted to reach an impedance which is high for the frequency of the current supplying an adjoining track circuit, the generator of the said track circuit and the receiver of the adjoining track circuit being connected to the terminals of said central dipole located at one end of the track circuit respectively, the receiver of the said track circuit and the generator of the adjoining track circuit being connected with the terminals of the central dipole located at the other end of the said track circuit.

As a result of this invention, we thus have a long track circuit without any insulating gaskets and having no bad detection zone at eaci of its extremities.

Along a first construction method, the dipoles consisting of the elements marked, 6, 7, 8 and 9 of the fitlers or electric gaskets represented on diagram 1 only comprise three series and parallel connected components, i.e. a capacitor and two inductance coils or two capacitors and an inductance coil. This arrangement enables dipoles 6 2' 25 and 8 to obtain a very low impedance (a few milli-ohms) for the frequency of the currents of track circuits A and C and a high impedance (several ohms) for the frequency of track circuit B. Dipoles 7 and 9 have a very low impedance for it; the frequency of the current of track circuit B and a high r 4 impedance for the frequency of supply currents of track circuits A and C.

Along a second construction method which can be used when the said circuit is supplied alternately by two currents of slightly different frequency (frequency modulation system), we shall use dipoles consisting of nine components as shown in diagram four. These components are grouped in series-parallel, i.e. four series circuits each comprising an inductance coil and a capacitor and a fifth capacitor in parallel with the four series circuits described above. The choice of the values for inductances and capacitors enables to obtain low and high impedance for alternate frequencies which have been chosen. In this second construction method, capacitors 3 and. 5 of diagram 1 must be replaced as shown on diagram five by capacitor 13 and inductance 13 assembled in series and connected in parallel with capacitor 14.

The present invention is now being described more precisely but only as a non-restrictive example in reference to the attached diagrams.

Diagram 1 is a drawing of the track circuit in compliance with the invention.

Diagram 2 represents the voltage variation at the terminals of the receiver of track circuit B when a pinpoint shunt moves along track circuit A towards track circuit C.

Chain-dotted lines on diagram 1 enable to locate the position of the shunt for the voltage indicated by the graph of diagram 2.

Diagram 3 shows various possible methods to make dipoles used in compliance with the first construction method. Coupling 3a and 3b are respectively equivalent to 3c and 3d.

Diagram 4 shows the dipole type which may be used for track circuits supplied by alternate frequencies.

Diagram 5 shows the dipole type which must be substituted to capacitora 3 aid 5 when supplying track circuits with alternate frequencies.

-ls d-ip o-e -a -onecedtoa.. short ta sectio acco g t SDiagram 6 shows the impedance variations of this last dipole connected to a short track section according to the frequency.

In accordance with the construction method shown on diagram 1, a track circuit B shown with continuous lines comprises a track section where both rails 1 act as electric conductor for the transmission of electric current from transmitter 2 connected to the terminals of a capacitor 3 and received by a receiver 4 connected to the terminals of a capacitor 5; Receiver 4 is responsible only to the current frequency of transmitter 2. This track circuit B is situated between two track circuits A and C shown in dotted line. Both these track circuits comprise Jipoles 6 and 7 which are common to track circuits B and C and dipole 8 and 9 which are common to track circuits A and B. Receiver shown in dotted lines is the receiver of track circuit C and is responsive exclusively to the current frequency of the transmitter of track circuit C which is not showr on this diagram. Likewise, transmitter 11 drawn in dotted lines supply track circuit A with current of a frequercy which is different from the frequency of track circuit B.

The role of dipole 7 is to create a short circuit for the frequency of track circuit B between both rails of the short track section used to make the filter (or electric gasket); this short circuit limits the propagation of the current from transmitter 2 of track circuit B, which enables to create a resonant circuit for the frequency of track circuit B with the self inductance of the track section between dipole 7 and capacitor 3; the impedance at the terminals of capacitor 3 is equal to severol ohms.

Likewise, for the frequency of track circuit C, the same Sdipole 7 has a high impedance which reduces slightly the transmission of the current emitted by the transmitter of track circuit C to receiver 0 of track circuit C. Dipole 6 situated at the other end of the track section making the "electric gasket", which we just referred to, play a similar role for currents of track Circuits B and C. It creates a short circuit for the current of tr^, k circuit C and does not allow the propagation of such current beyond the connection points of the said dipole to the rails towards dipole 8. Such short circuit for the frequency of the current of track circuit C enables to create, with the own inductance of the track section between dipole 6 and capacitor 3, a resonant circuit at the frequency of track circuit C; the impedance at the terminals of capacitor 3 is equal to several ohms. The impedance at the terminals of capacitor 3 is high for the frequency of track circuit B and the impedance is also high for the frequency of track circuit C.

°o 1 The same phenomena re-appear at the other end of nc° track circuit B with dipole 0, capacitor 5, dipole 9.

B°^

a With the provisions described above, it is possible aa to make a track circuit which complies with diagram 1 measuring 2500 metres long and to secure a minimum shunt of So 0.25 ohm on the total length of this track circuit as well as on the adjoining track circuits. This track circuit uses a 1700 Hz frequency current and the adjoining track circuits o a use 2300 Hz frequency current, the track circuits mentioned o .o use compensating capacitors as usually used in these circumstances and the value of this shunt for any track *oo insulation varying from 1.5 ohm per km to 1000 ohms per km is secured. Let's keep in mind that with the devices known presently, it would be impossible to secure a pinpoint shunt o of 0. 5 ohm on a distance of at least 15 metres around capacitors 3 or Let's note that the dipoles are constructed for given resonance frequencies and that their position on each side of capacitors 3 or 5 is determined according to the overlapping zone desired.

With the same dipoles, it is therefore easy to make different overlappings by giving capacitors 3 or 5 the values which correspond with the desired length of the overlapping zone. It is important to note that the characteristics of the dipoles are independent of the length of the track sections used to make the filters or electrical gaskets.

I

Claims

1. A track circuit of the type specified, including a rail track section limied at both ends by a set of three dipoles each connected between both rails and spaced a short distance from each other, a central dipole of each set including a capacitive element and adapted to reach an impedance which is high for the frequency of the current supplying an adjoining track circuit, the generator of the said track circuit and the receiver of the adjoining track circuit being connected to the terminals of said central dipole located at one end of the track circuit respectively, the receiver of the said track circuit and the generator of *"the adjoining track circuit being connected with the eterminals of the central dipole located at the other end of *the said track circuit. a

2. Track circuit according to Claim 1, wherein the central dipole of each three dipole set which limits the track circuit at each end is a capacitor. o

3. Track circuit according to Claim 2, wherein the i O' o three dipole set which limits the track circuit comprises an i inductance coil and two capacitors for the dipole located on j one side of the capacitor and two,inductance coils and a capacitor for the dipole located on the other side of the capacitor and that the dipoles consisting of the same elements are located between the two capacitors located respectively at each end of the track circuit.

4. Track circuit according to Claim 1, wherein the central dipole of the three dipole set consists of an inductance coil connected in parallel with a second capacitor.

LJD/CH (1.28) T i n i j j L B 8 Track circuit according to Claim 4, wherein the dipoles placed each side of the dipole include four inductanc coils and five capacitors which form the five branches of a parallel circuit, four branches of which circuit comprise each a series circuit including an inductance coil and a capacitor and the fifth branch of which circuit is a capacitor.

6. A track circuit substantially as hereinbefore described when having reference to the accompanying drawings. DATED THIS 27TH DAY OF JULY, 1988 GILBERT ALT. EDWD. WATERS SONS, PATENT ATTORNEYS, 50 QUEEN STREET, MELBOURNE, VICTORIA 3000, AUSTRALIA rs a 9 I ",nr Pi 99 *I Q9C ODog (1 1~ D ,aa Llbro as cr It O D 9 d0 i s, o B D i guO P i)~ LJD:JC (8.4)