CA1281116C - Solid state railroad lights/gate controller - Google Patents

Abstract

SOLID STATE RAILROAD LIGHTS/GATE CONTROLLER

Abstract of the Disclosure A railroad crossing lights/gate controller for effecting operation of the crossing lights and lowering of the crossing gate during normal train operating conditions and during a gate con-troller failure mode includes a train sensing input, a gate con-trol circuit, a lights control circuit, a solid state logic and monitor circuit and a fail/safe relay. The train sensing input provides one signal condition when the approach of a train is sensed and another signal condition when no train is sensed. This input is connected to the solid state logic and monitor circuit which is also connected to the gate control circuit and the lights control circuit. The gate control circuit has power applied thereto to maintain the gate in a raised position when the train sensing input indicates a no train condition and the lights con-trol circuit has power supplied thereto to operate the lights in a flashing condition when the train sensing input indicates the approach of a train. The logic and monitor circuit applies and removes power to the gate and lights control circuits in accord-ance with the signals at the input. The fail/safe relay is con-nected to the logic and monitor circuit and to the gate and lights control circuits to automatically remove power to the gate control circuit and apply power to operate the lights in the event no pow-er is applied thereto. The logic and monitor circuit further senses the application of power to the gate control circuit and to the lights control circuit and removes power to the fail/safe relay under certain sensed conditions.

Description

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Summary of the Invention ~ he present invention relates to controllers for rail-road grade crossings and in particular to a controller for effect-ing operation of the crossing lights and lowering oE the crossing gates, both during nor~al train operating conditions and during a controller failure ]~ode.
' A primary purpose of the present invention is a crossing lights/gate controller which has solid state logic and utilizes a fail/safe or vital relay to insure that under any abnormal condi-tion the gates will come down and the lights will be powered.
Another purpose is a grade crossing controller of the type described which is simple in construction and reliably oper-able.
Another purpose is a crossing lights/gate controller which includes a fail/safe or vital relay which responds both to the solid state logic circuit and to a loss of power or other abnormal condition to insure that the gate will be lowered and the lights will be powered.
Other purposes will appear in the en~uing specification, drawing and claims.
Brief_Description of the Drawing The invention is illustrated in the following block diagram of the control circuit described herein.

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Description of the Preferred Embodiment In the railroad industry safety is a paramount concern and in such areas as railroad signal systems and railroad air brakes, whenever there is what appears to be a failure, the train brakes are operated or the si~nal system goes dark, which is an indication to a train crew of a red or danger condition. Thus, what can be perceived as a system failure has the effect oE shut-ting down train operations.
The situation is somewhat diferent at a railroad grade crossing, as in that situation when there is what can be perceived as a failure mode, the crossing equipment must be operated. The gate must come down and the signal lights must be illuminated.
Accordingly, it is necessary to provide a means to automatically insure that any type of abnormal condition will effectively cause the lights and the gate to function in a manner so as to warn a person using the grade crossing.
In the railroad industry certain components have the term "vital" applied thereto when such components are required to - never be able to fail, or always to operate in a predetermined manner in the event of a failure o~ some other part o the system.
In the present invention, a relay has been termed a vital relay in that whenever certain conditions are brought about in the grade crossing control, this relay will have its contacts always ~ove to a certain predetermined position, which position is ef~ective to cause operation of the gate and illumination of the signal lights. Such a vital relay is combined in the present inv~ntion with solid state logic which insures operation of the grade cros-sing equipment in the normal manner and also insures that the ~i-tal relay will ~unction in the appropriate manner in an emergency 3~ situation. `
In the drawing, an input is indicated at 10 and will be the input signal from themotion sensing circuit which is used at grade crossings to detect the presence of an approaching train and thereby cause operation of the gates and lights. U. S. Patent 3,944,173, assigned to the assignee of the present application, illustrates a railroad crossing motion detector of the type which may be used to provide an input at terminals 10. Terminals 10 are connected to a DC-to-DC converter 12 which converts the voltage level at terminals 10 to a level more appropriate for the log~c circuit to be described. The normal input to ter~inals 10 will be a signal at a predetermined voltage level when there is no train approaching or present. When a ~rain has been sensed, the custom-ary output from a motion detector is no input at terminals 10 andthe lack of a signal is known to indicate that the crossing appa-ratus should be operated.
A logic and vital monitor microprocessor is indicated at 14 and is connected to converter 1~ and thus receives an input of the signal indicating the presence or absence of a train at the crossing. Logic circuit 14 will have programmed firmware to per-form the functions described below.
Warning lights are indicated at 16 and lB, with these lights representing the plurality of lights which are normally present at every grade crossing. Light 16 is connected to a relay contact arm 20 and a relay contact arm 22. Light 18 is connected to relay contact arm 22 and to a relay contact arm 24. ~ach of contact arms 20-24 are movable between upper and lower contacts, with the normal position of the relays being for the arms to be in contact with the upper contacts.
A source of either AC or DC power is applied to a ter-minal 26 which is connected to a switch 28, the position of which is controlled by logic circuit 14. The other side of switch 28 is connected to the upper co'ntact for contact arm 200 Flasher drive switches 30 and 32`are conn~cted across the three sets of relay contacts which cooperate with contact arms 20-24 to cause opera tion of the lights. The flashers cause the well~known flashing or periodic application of power to lights 16 and 18. The lower contact of each of the above-described pairs of contacts are con-nected to voltage or power sources designated N1, B1 and N1, re-spectively, with terminal 26 having polarity B1. If the signal lights are operated by AC power, the terminals designate the hot side of the line and ground, whereas, if DC power is being ap-plied, the terminals will be positive and negative.
The control for flashers F1 and F2 is indicated to come from loyic circuit 14 where the flasher drive outputs are indicat-ed.
A crossing gate is normally maintained in the up or raised position by the application of power. Thus, DC power from terminal 34 is applied ~o a normally closed switch 36 to apply power to a contact 38 which cooperates with contact arm 40 to apply DC power to the gate drive to main~ain it in an up position.
Contact arm 42, also a part of the gate power supply circuit is in contact with a contact 44 connected to power supply terminal 46. Thus, there is a closed circuit from positive to negative through the described relay contacts and relay contact arms which will maintain the gate in an up position as long as switch 36 is closed.
The vital relay is indicated at 48 and may have two relay coils, an upper coil indicated at 50, having a direct con nection to input 10, and a lower coil 52 connected to a bridge rectifier 54 and through a transformer 56 to logic circui~ 14.
Power to either of coils 50 or 52 will maintain contact arms 20, 22, 24, 40 and 42 in the position shown. Under normal operating conditions, power will be supplied to coil 52 by logic circuit 14.
Although not shown, the power supply will include both AC and DC sources and more particularly a back-up DC battery which is at every grade crossing and it utilized to provide assurance that the crossing system will operate in the event of a local power failure.

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Under normal operating conditions, the gate control circuit and the lights control circuit have their relay contacts in the position shown. As long as a signal is present at input terminal 10, logic circuit 14 will maintain switch 28 ln the open position and switch 36 in the closed position. Thus, power is supplied to the gate to maintain it in a raised position and no power is supplied to the warning lights. In the event a train is sensed on the section of track adjacent to the ~rade crossing, there will be a loss of signal at input 10, which loss of signal will cause the logic and vital monitor microprocessor to close switch 28 and open switch 36. The flasher drive will also be activated. The closing of switch 28 will apply power to illumi-nate the lights and the flashers will simultaneously function to provide the well known flashing light condition. The removal of power by the opening of switch 36 will cause the gate to be lower-ed as it is maintained in a raised position by the application of power.
There are three circuit condition sensors which are mon-itored by logic circuit 14~ Sensor 58 monitors the application o~ power to the lights. Sensor 60 monitors the application of power to the gate circuit and sensor 62 monitors the rate at whlch the flashers function. At such time as t~ere is a loss of signal at terminals 10, the gate and lights will function in the manner described, providing that each of sensors 58, 60 and 62 indicate that power is applied to the lights, power is not applied to the gate, and the flashers are functioning in a normal manner. ~n the event that any one of the three described sensors gives an indica-tion which is not appropriate for a train present input signal to the logic circuit from terminals 10, the logic circuit will remove power from transformer 56 and thus from coil 52 of vital relay 48.
Since there is no power to coil 50l contact arms 20, 22, 249 40 and 42 will each move to a position opposite that shown in the drawing. Automatically, when any malfunction is detected by any any one of the three sensors, the vital relay will operate. Sim-ilarly, if there is a loss of power in the logic circuit, the vi-tal relay will function, assuming no signal at input 10, which will cause all of the contact arms controlled by coils 50 and 52 to move to a a position opposite that shown in the ~rawings. The vital relay is either so mechanically positioned or khe contact arms have spring contro~ such that in the event oE a loss of power to coils 50 and 52, the contact arms automatically will move away from the position shown.
When contact arms 20, 22 and 24 all move to a down posi-tion, lights 16 and 18 will be connected directly to the power supply represented by terminals N1 and B1. The lights will be illu~inated, although they will not be flashed, as the flashers are not in the circuit when the contact arms are in the down posi-tion. Thus, there will be continuous illumination o~ the lights at the grade crossing.
In like manner, when contact arms 40 and 42 move away from contacts 38 and 44, respectively, power is removed from the gate circuit which causes the gate to be lowered.
The direct connection between input ~0 and coil 50 of vital relay 48 provides a reliability enhancement to insure that the vital relay is responsive to a signal at the input and is not misled by a loss of power from the vital relay. The vital relay is used to turn on the lights and to lower the gate when something is wrong in the system, regardless of what it may be. There may be a power failure, or there ma~ be a failure in the logic circuit or there may be some other type of malfunctionO When something does go wrong, because of the nature of the rela~l the gate is lowered and the lights are turned on.
Whereas the preferred form of the invention has been shown and described herein, it should be realized that there ma~
be many modi~ications, substitutions and alterations thereto.

Claims (5)

1. A crossing lights/gate controller for effecting operation of the crossing lights and lowering of the crossing gate during normal train operating conditions and during a controller failure mode including, a train sensing input providing one signal condition when the approach of a train is sensed and another signal condi-tion when no train is sensed, a gate control circuit which has power supplied thereto to maintain the gate in a raised position when the train sensing input indicates a no train condition, a lights control circuit which has power supplied there-to to operate the lights in a flashing condition when the train sensing input indicates the approach of a train, a solid state logic and monitor circuit connected to said input, gate control circuit, and lights control circuit, said logic and monitor circuit applying and removing power to said gate and lights control circuits in accordance with the signals at said input, and a fail/safe relay connected to said logic and mon-itor circuit and said gate and lights control circuits, which re-lay automatically removes power to said gate control circuit and applies power to operate the lights in the event no power is ap-plied thereto.

2. The controller of claim 1 further characterized in that said logic and monitor circuit monitors the application of power to said gate control circuit and said lights control cir-cuit, said relay automatically removing power to said gate control circuit and applying power to operate the lights in the event the logic and monitor circuit has a train sensed input and senses ei-ther power to the gate control circuit or no power to the lights control circuit.

3. The controller of claim 2 further characterized in that said logic and monitor circuit also monitors the rate at which said lights flash, with the flashing rate, along with the sensed conditions of power to the gate control circuit or no power to the lights control circuit, being one of the conditions which is effective to remove power to said fail/safe relay.

4. The controller of claim 1 further characterized in that said lights control circuit and gate control circuit each include relays whose contacts have a normal position in which power is supplied to maintain the gate in a raised position and power is supplied to operate the lights in a flashing condition which relay contacts will move to a contrary position upon the loss of power at said fail/safe relay.

5. The controller of claim 1 further characterized by and including a direct connection between said input and said fail/safe relay.