US3004149A

US3004149A - Railway track occupancy detectors

Info

Publication number: US3004149A
Application number: US849226A
Authority: US
Inventors: Crawford E Staples
Original assignee: Westinghouse Air Brake Co
Current assignee: Westinghouse Air Brake Co
Priority date: 1959-10-28
Filing date: 1959-10-28
Publication date: 1961-10-10
Anticipated expiration: 1978-10-10

Description

Oct. 10, 1961 c. E. STAPLES 3,004,149

RAILWAY TRACK OCCUPANCY DETECTORS Filed Oct. 28, 1959 Light Source 6 D :p Zzgbi Beam 1 E Li lnf Responsive Device I? 4 P02 TH E I; i 5 i I H i4 4=- ""la,i I L -.l i

i I i 1 iv F 1) To [12d icaion or Conral Apparazzs INVENTOR.

Crawfordlfdizyks BY H15 ATTORNEY tion of Pennsylvania Filed Oct. 28, 1959, Ser. No. 849,226 6 Claims. (Cl. 246-29) My invention relates to a railway track occupancy detector, and particularly to a track occupancy detector arrangement for a track section of sufficiently short length that it can at times be spanned by the inside pairs of wheels and axles of the trucks of the railway car, having the greatest distance between said pairs of wheels, to travel said track section.

In many railway installations such as interlockings, classification yards, etc., it is often expedient or necessary to provide short detector track sections for detecting the presence of engines or railway cars in the tracks included in the interlocking or yard. Where any such track section is of such extremely short length that it can be spanned by the inside pairs of wheels and axles of the trucks of a railway car to traverse the section, it is necessary to supplement the usual detector track circuit, provided for the section, with an additional occupancy detection arrangement to insure that detection of the presence of such a car is not lost when the section is spanned by the wheels and axles of the car. One such arran ement is shown and described in the application for Letters Patent of the United States of William A. Robison, Jr., Serial No. 806,120, filed April 13, 1959, for Railway Switch Locking Apparatus, which application is assigned to the assignee of the present application. The apparatus of that application employs a coded light beam and a light responsive device to supplement the usual detector track circuit in the detection of the presence of a railway car in a short track section. The coding of the light beam and the use of a decoding transformer insures that the light responsive device is intact, that is, that a short circuit, operating to retain the relay responsive to the light beam energized when the beam is.

interrupted by a railway car, does not exist in the light responsive device.

It is, accordingly, one object of my present invention to provide an arrangement employing a light beam and a light responsive device to supplement the usual detector track circuit and providing equivalent certainty that the light responsive device is intact, but without the necessity of coding the light beam and employing a decoding transformer, thereby providing a more economical arrangement due to the elimination of a code generator or code transmitter, and the decoding transformer.

It is a second object of my invention to provide an arrangement of the type described in which the light beam is normally off, thereby providing additional economy in the conservation of the power for illuminating the light source.

Other objects and characteristic features of my invention will become apparent as the description proceeds.

I accomplish the foregoing objects of my invention by employing a normally deenergized light source which is energized only when it is necessary to transmit a light beam for detection of the presence of a railway car, and an energy storing or capacitor-resistor unit to cycle check the closing of a front and back contact of a relay controlled by a device responsive to the receipt of the light beam, thereby insuring that the light responsive device is not short circuited and the relay thus continuously in a picked-up position.

I shall first describe one embodiment of my invention 3,064,149 Patented Oct. 16, 1961 and shall then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention.

Referring to the drawing, the reference character A designates a stretch of railway track including rails 1 and la divided at points D and E by insulated joints 2 to form a track section DE which is sufficiently short to be spanned by the wheels and axles of a car, as previously set forth. This track section is provided with a track circuit comprising a battery 4 and a track relay TR arranged in a manner well known in the art, such that the contacts of track relay TR are in a normally picked-up position.

In the particular embodiment of my invention shown, intrusion detection apparatus is shown including a source of light 6 located on one side of track A and a cooperat ing light responsive device 8 located on the opposite side of the track, the device 8 so positioned relative to light source 6 as to be responsive to a light beam from said source projected across the track. The light source 6 and light responsive device 8 are thus arranged that light from the source will strike the device when the light source is energized but will be interrupted by a car traversing track section DE.

A relay PCR of the neutral type is provided with a control circuit, including a battery 12, controlled by device 8. Contact a of relay PCR is operated to its pickedup or released positions according as device 8 does or does not receive light from the source 6. Such light responsive arrangements are well known.

It should be pointed out at this time that a suitable source of direct current is provided for operation of apparatus other than the track circuit apparatus and the relay operated by the light responsive device 8, this source being preferably a battery of proper voltage and capacity which, for the sake of simplicity, is not shown in the drawings, but its positive and negative terminals are identified by the conventional reference characters B and N respectively.

An additional relay designated HR is provided which is controlled by the track relay TR and the light beam responsive relay PCR. This relay is a stick relay which is normally maintained energized by a stick circuit extending from terminal B of the battery over front contact b of relay TR, the front point of its own contact a, and through the winding of the relay to terminal N of the battery.

Relay HR is provided with a pickup circuit which is energized by a charge of current from the aforementioned energy storing or capacitor-resistor unit 14 to be described. This pickup circuit extends from the righthand side of unit 14 over the front point of contact a of relay TR in its picked-up position, the front point of contact a of relay PCR in its picked-up position and through the winding of relay HR to the left-hand side of unit 14.

Capacitor-resistor unit 14 has a charging circuit extending from battery terminal B over the back point ofv contact a of relay PCR, the front point of contact a of relay TR, and through the unit to terminal N of the battery. It is thus apparent that a charge of current is supplied to unit 14 to be stored when relay PCR is released and track relay TR is picked up. The utility of such arrangement will become more apparent later in this description.

As previously set forth the light source 6 is normally deenergized and, therefore, the light beam is extin guished. The circuit for energizing the light source extends from terminal B of the battery over front contact [2 of relay TR, the back point of contact a of relay HR and through the filament of the light source, such filament for purpose of simplicity not being shown in the drawing, to terminal N of the battery. The light source is, there fore, energized when relay TR is in its picked-up position and relay HR is in its released position as will be described hereinafter. Contact I) of relay HR may be employed to control any desired apparatus such as a track occupancy indicator, a signal, a switch etc., but is shown in the drawing as controlling a circuit for supplying current to indication or control apparatus. However, it is to be'understood that a contact or contacts of relay HR can be employed to control any of the apparatus well known in the art which is normally controlled by a contact or contacts of the track relay of a normally energized conventional type track circuit.

I will now describe the operation of the apparatus of my invention when a railway car capable of spanning the track section, as previously set forth, enters and proceeds through the track section DE. I will assume for purposes of this description that the apparatus is in its normal condition as shown in the drawing, that is, relays TR and HR are in their picked-up positions, the light source 6 is deenergized, and relay PCR is released.

When the car enters track section D-E from either direction, the track circuit is shunted and track relay TR releases. The release of track relay TR opens the stick circuit for relay HR which also releases. The release of track relay TR also closes at the back point of its contact a a discharge circuit for unit 14. This circuit assures at this time that any energy stored in unit 14 is discharged, and extends from the right-hand side of unit 14 over the back point of contact a of relay TR to the left-hand side of the unit. This is the only operation of the detector apparatus that takes place at this time.

When the front truck of the car has proceeded completely through section DE and has vacated the section, and the rear truck has not yet entered the section, that is the wheels and axles of the car are spanning the section, track relay TR again picks up. The picking up of track relay TR closes over its front contact b and the back point of contact a of relay HR the energizing circuit for the light source 6. However, the light beam projected by the light source is interrupted by the sides of the car so the light responsive device 8 is not actuated and relay PCR remains in its original position. A charge of energy is supplied to unit 14 at this time over the back point of contact a of relay PCR and the front point of contact a of relay TR, but no further action takes place at this time.

When the rear truck of the car enters track section DE, track relay TR is again released, unit 14 is again discharged, and the light source 6 is again deenergized. The apparatus, therefore, is temporarily in the same condition as when the front truck of the car occupied the track section. When the rear truck of the car vacates the track section, relay TR again picks up, and since the energizing circuit for the light source 6 is now closed and the sides of the car no longer interrupt the light beam, the light responsive device 8 will be actuated to cause relay PCR to be picked up by the energy supplied from battery 12. However, previous to relay PCR picking up, unit 14 will be charged over the circuit including the back point of contact a of relay PCR and the front point of contact a of relay TR. Therefore, when relay PCR picks up, the discharge circuit for unit 14 through the winding of relay HR is completed and relay HR is operated to its picked-up position by the energy stored in capacitor-resistor unit 1 The picking up of relay HR opens the energizing circuit for light source 8, the light beam is extinguished, relay PCR is subsequently released, and the apparatus is restored to its normal condition.

It will be noted that should a short circuit occur in the light responsive device 8 which would cause relay PCR to be continuously picked up, the charging circuit for unit 14 is never completed, and, therefore, relay HR when released cannot again be picked up until the short circuit is removed. In other words, by the arrangement of my invention I have provided a means whereby relay PCR must close both its back and front contact points in that order, in order that relay HR can be picked up following a period of release of relay HR. This operation cycle checks the operation of relay PCR, and is considered equivalent to the operation of a code following relay by a coded light beam.

While I have shown and described only one form of apparatus embodying my invention, it should be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a track occupancy detection arrangement for a section of railway track capable of being spanned by the Wheels and axles of a railway car, the combination comprising, a track circuit for said track section including a source of current and a track relay actuated from a first position to a second position when the track section is occupied, a light responsive device, a normally deenergized light source so disposed in relation to said light responsive device and said track section that a beam of light projected from the source to the device is interrupted when a portion of the track section is occupied, a second relay, a stick circuit for said second relay including one of its own front contacts and a first contact of said track relay closed in the first position of the track relay, an energizing circuit for said light source including said first contact of said track relay and a back contact of said second relay, a third relay, means controlled by said light responsive device for picking up said third relay when said device is receiving light from said source, an energy storing device, a circuit for storing a charge of energy in said energy storing device, said circuit including a back contact of said third relay and a second contact of said track relay closed in the first position of the track relay; and a pickup circuit for said second relay including said energy storing device, said second contact of said track relay, and a front contact of said third relay.

2. In a track occupancy detector arrangement for a section of railway track capable of being spanned by the wheels and axles of a railway car and including a track circuit for said section including a normally picked-up track relay, the combination comprising, a normally deenergized light source capable when energized of projecting a light beam across said section of track, a light responsive device on the opposite side of said section of track from said light source and responsive to said light beam, a normally released second relay, a normally picked-up third relay, means controlled by said track relay for releasing said third relay when the track relay is released, means controlled by said track relay and said third relay for energizing said light source when the track relay and the third relay are picked-up and released respectively, means controlled by said light responsive device for picking up said second relay when the device responds to said light beam, an energy storing device, means controlled by said track relay and said second relay for storing a charge of energy in said energy storing device when said track relay is picked up and said second relay is released; and means controlled by said energy storing device, said track relay, and said second relay for picking up said third relay only when a charge of energy is stored in the energy storing device, and the track relay and the second relay are both picked up.

3. In a track occupancy detector arrangement for a section of railway track capable of being spanned by the wheels and axles of a railway car and including a track circuit for said section including a source of current and a normally energized track relay, the combination comprising, a normally deenergized light source on one side of said track section and capable when energized of projecting a light beam across the section, a light responsive device on the opposite side of said track section and so arranged as to receive said light beam when projected, a normally deenergized second relay, means controlled by said device for energizing said second relay when said light beam is received by the device, a third relay, a stick circuit for said third relay including a first front contact of said track relay, an energizing circuit for said light source including said first front contact of said track relay and a back contact of said third relay, a capacitor, an energizing circuit for said capacitor including a back contact of said second relay and a second front contact of said track relay, and an energizing circuit for said third relay including said second front contact of the track relay and a front contact of said second relay.

4. In a track occupancy detector arrangement for a section of railway track capable of being spanned by the wheels and axles of a railway car and including a track circuit for said section including a source of current and a normally energized track relay, the combination comprising, a normally energized second relay, means controlled by said track relay for maintaining said second relay energized when it is once energized and so long as said track relay is energized, a light source arranged when energized to project a light beam across the rails of said track section, a light responsive device on the opposite Side of said track section and arranged to receive said light beam when projected, a normally deenergized third relay, means controlled by said track relay and said second relay for energ zing said light source when said track relay is energized and said second relay is deenergized, means controlled by said light responsive device for energizing said third relay when the device receives said light beam, an energy storing device, means controlled by said track relay and said third relay for storing energy in said storing device when said track relay is energized and said third relay is deenergized; and means controlled by said energy storing device, said track relay, and said third relay for energizing said second relay When energy is stored in the energy storing device, and the track relay and the third relay are both energized.

5. In a track occupancy detector arrangement for a section of railway track capable of being spanned by the wheels and axles of a railway car and including a track circuit for said section including a source of current and a track relay energized when the track section is unoccupied,

the combination comprising, a light source arranged when energized to project a light beam across the rails of said track section, a light responsive device on the opposite side of said track section and arranged to receive said light beam when projected, a normally deenergized second relay, means controlled by said light responsive device for energizing said second relay when the device receives said light beam, a normally energized stick relay, means controlled by said track relay for deenergizing said stick relay when the track relay is deenergized, means controlled by said track relay when energized following a period of deenergization for energizing said light source, and means controlled by said track relay and said second relay for reenergizing said stick relay only when the track relay is energized and the second relay is thereafter energized.

6. A track occupancy detection arrangement for a sec-- tion of railway track capable of being spanned by the wheels of a railway car, comprising, in combination, a track occupancy detection device for detecting the presence in said track section of the wheels of a railway car and actuated from a first position to a second position by the occupancy of any part of said track section by the wheels of a railway car, a first relay, means controlled by said detection device for maintaining said first relay energized when once energized and only so long as the device occupies its first position, a second relay, means controlled by said detection device and said first relay for energizing said second relay only when the first relay is deenergized and the detection device again occupies its first position following the passage of said railway car through said track section, a capacitor, means controlled by said detection device and said second relay for charging said capacitor when the detection device occupies its first position following the passage of said railway car through said track section and previous to the energization of the second relay, and means controlled by said second relay and said capacitor for reenergizing said first relay when the second relay is energized following said passage of the railway car.

References Cited in the file of this patent UNITED STATES PATENTS 1,839,784 Livingston Jan. 5, 1932 2,465,794 Fereday Mar. 29, 1949 2,549,146 Van Horn n Apr. 17, 1951 2,607,001 Jerome Aug. 12, 1952 2,654,081 Staples Sept. 29, 1953