US 4,304,377 AGranted

Electrical block separating joints for railway signaling systems

AssigneeCompagnie de Signaux et d'Entreprises Electriques

InventorPierre Pitard

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Abstract

An electrical joint for separating adjacent block circuits of a railway signaling system in which the rails of the railway track serve as conductors. The upstream circuit block carries first frequency signals and the downstream block circuit carries second frequency signals. The electrical block separating joints are bounded by tuning units of which one may be a mere impedance and which are responsive to the frequencies of the circuit blocks and constitute respectively a low impedance for the first or second frequency and a capacitive impedance for the other of the first or second frequency. There are transmitter and receiver units the latter of which is associated to activate a control device, e.g. a relay, for the associated block circuit to de-activate the control device when a vehicle enters the electrical joint by a shunting effect. An overlapping shunting effect is produced in the electrical joint by one, two or three inductive loops wherein coupled to the receiver and transmitter units which prevent a vehicle axle remaining in the electrical joint undetected.

Claims20

Dependent claims

In a railway block signaling system in which rails of the railway track serve as electrical conductors, an electrical joint for separating two adjacent block circuits respectively upstream and downstream relative to the direction of traffic flow, the upstream block circuit being adapted to carry electric signals of a first frequency and said downstream block circuit being adapted to carry electric signals of a second frequency, said electrical block separating joint being bounded at its respective ends by upstream impedance means selected as a function of the first frequency and constituting a low value at the second frequency and a capacitive value at the first frequency, and downstream impedance means selected as a function of the second frequency and constituting a low value at the first frequency and a capacitive value at the second frequency, a receiver unit and a transmitter unit, said upstream impedance means being associated with a selected one of the receiver unit and the transmitter unit, and said downstream impedance means being associated with the nonselected one of the receiver unit and the transmitter unit, said receiver unit being normally adapted to activate a control device for its associated block circuit and de-activate the control device in response to the shunting effect caused by a vehicle axle present in the associated block circuit, and an inductive loop coupled to one said receiver or transmitter unit and constructed and arranged so that upon presence of a vehicle axle the gradual return of the amplitude of the first frequency signal to the amplitude of activation of the control device for the upstream circuit block occurs after the gradual attentuation of the second frequency signals in the downstream block circuit to the amplitude causing the de-activation of the control device thereby providing an overlapping shunting effect zone.

In a railway block signaling system in which rails of the railway track serve as electrical conductors, an electrical joint for separating two adjacent block circuits respectively upstream and downstream relative to the direction of traffic flow, the upstream block circuit being adapted to carry electric signals of a first frequency and said downstream block circuit being adapted to carry electric signals of a second frequency, said electrical block separating joint being bounded at its respective ends by upstream impedance means selected as a function of the first frequency and constituting a low value at the second frequency and a capacitive value at the first frequency, and a downstream impedance means selected as a function of the second frequency and constituting a low value at the first frequency and a capacitive value at the second frequency, a receiver unit and a transmitter unit, said upstream impedance means being associated with a selected one of the receiver unit and the transmitter unit, and said downstream impedance means being associated with the nonselected one of the receiver unit and the transmitter unit, said receiver unit being normally adapted to activate a control device for its associated block circuit and de-activate the control device in response to the shunting effect caused by a vehicle axle present in the associated block circuit, and a first or upstream inductive loop coupled to said receiver unit and a second or downstream inductive loop coupled to said transmitter unit, said inductive loops being constructed and arranged so that upon presence of a vehicle axle the gradual return of the amplitude of the first frequency signal to the amplitude of activation of the control device for the upstream circuit block occurs after the gradual attenuation of the second frequency signals in the downstream block circuit to the amplitude causing the de-activation of the control device thereby providing an overlapping shunting effect zone.

Dependencies are inferred from the claim text.