Semiconductor controlled safety time delay relay

Claim 2

A signal delay device for controlling a railroad signalling circuit or the like with a magnetic biased relay having a stick circuit through one of its sets of contacts and wherein an external contact supplies a DC signal through a pair of terminals to the delay device comprising: a charging circuit including in series connection across the pair of terminals a capacitor, the coil of said relay and a time element resistor, with the coil oriented in said charging circuit to produce an increase in the bias of the relay from charging current flowing through the coil; a discharge circuit including said capacitor, said coil and a normally open semiconductor switch arranged to discharge the capacitor through the coil, the discharge current being passed reversely through the coil in a direction to overcome the bias and energize the relay; means responsive to the DC signal applied from the external contact and said terminals for generating a preselected control voltage for closing the semiconductor switch at a preselected voltage level generated in the charging circuit; said stick circuit including the coil and the switch in series relationship for passing current through the coil in a direction continuing to overcome the bias of the relay.

Claim 3

The device as recited in claim 1 wherein the switch-closing means further comprises said semiconductor switch, said device having a pair of power terminals and a control gate terminal, with said power terminals coupled across the coil and the capacitor, and a pair of series-connected resistors coupled across the DC signal terminals for producing a reference voltage therebetween, with the control gate terminal coupled to the reference voltage for controlling the conduction of the semiconductor switch.

Claim 4

The device as recited in claim 1 and further including a bypass rectifier coupled across the coil in a direction for passing charging current around the coil and presenting a high impedance to discharge currents.

Claim 5

A signal delay device for controlling a railroad signalling circuit or the like with a relay wherein an external contact supplies a DC signal through a pair of input terminals to the delay device, comprising: a pair of resistors connected in series relationship across the pair of input terminals; a semiconductor switching device including a trigger input coupled to the junction betweEn the resistors and having a pair of power terminals; a capacitor and a time element resistor connected to form a time element network; said relay being a magnetic biased relay having a coil for actuating the relay in response to current flowing in a first direction through the coil and having plural sets of contacts, a stick circuit including one of the sets of contacts, coupled across the coil to conduct current therethrough to one of the input terminals; said capacitor and coil connected in series relationship across the power terminals of the semiconductor switch with one of the power terminals of the switch coupled to the other input terminal and the other power terminal coupled through the time element resistor to the one input terminal, said coil having a common junction with the time element resistor and the other power terminal, said coil being oriented to increase the bias in response to charging currents flowing through the capacitor and overcome the bias in response to discharge currents from the capacitor.

Claim 6

A signal delay device for controlling a railroad signalling circuit or the like with a relay wherein an external contact supplies a DC signal through a pair of input terminals to the delay device, comprising: a pair of resistors connected in series relationship across the pair of input terminals; a semiconductor switching device including a trigger input coupled to the junction betweEn the resistors and having a pair of power terminals; a capacitor and a time element resistor connected to form a time element network; said relay being a magnetic biased relay having a coil for actuating the relay in response to current flowing in a first direction through the coil and having plural sets of contacts, a stick circuit including one of the sets of contacts, coupled across the coil to conduct current therethrough to one of the input terminals; said capacitor and coil connected in series relationship across the power terminals of the semiconductor switch with one of the power terminals of the switch coupled to the other input terminal and the other power terminal coupled through the time element resistor to the one input terminal, said coil having a common junction with the time element resistor and the other power terminal, said coil being oriented to increase the bias in response to charging currents flowing through the capacitor and overcome the bias in response to discharge currents from the capacitor.