US3683176A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Presence detector
Assignee: Individual
•
Filing: 1970-07-21
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Granted: 1972-08-08
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Expires: 1990-07-21
Abstract
Abstract Herein is described an apparatus for detecting the presence of a car within a section of railway track. The track section is defined by low impedance electrical connections between rails at opposite ends thereof, and the section is inductively coupled to transmitter and receiver units. In one embodiment, the transmitter unit operates in the audio frequency range and the proximity of a car is detected by a reduction in the received signal due to electromagnetic coupling of the metallic mass of the car to the track section. In another embodiment the transmitter operates in the ultrasonic frequency range and the presence of a car within the section is detected by a reduction in the received signal caused by the shunting effect of the wheels and axle of the car. In a third embodiment the transmitter unit applies a pair of signals at different frequencies, and the proximity of the metallic mass of the car is detected by a variation in the received amplitude of one of the signals, and the shunting effect of the wheels-axle set is detected by a variation in the other signal.
Inventors
- 👤 George B Crofts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:44
CPC Classifications
B; B61; B61L; B61L1/00; B61L1/18; B61L1/181; B61L1/187
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
166 words
An apparatus for detecting the presence of a car within a section of a railway track defined by low impedance electrical connections across the rails at opposite ends of the track section, said apparatus including: transmitter means including a pair of oscillators for inductively coupling electrical energy at first and second frequencies to said track section; receiver means inductively coupled to said track section for providing first and second electrical signals representative of the electrical energy at said first and second frequencies, respectively, coupled to said receiver means from track section; detection means, coupled to said receiver means, for detecting variations in said first and second electrical signals; means for indicating the presence of a car within said track section as a function of the variations in said first and second electrical signals; a pair of transmitter track coupling inductor circuits; and means for applying the output signals from said pair of oscillators in an electrical parallel arrangement to said pair of transmitter coupling inductor circuits.
Claim 2
Independent Claim
166 words
An apparatus for detecting the presence of a car within a section of a railway track defined by low impedance electrical connections across the rails at opposite ends of the track section, said apparatus including: transmitter means including a pair of oscillators for inductively coupling electrical energy at first and second frequencies to said track section; receiver means inductively coupled to said track section for providing first and second electrical signals representative of the electrical energy at said first and second frequencies, respectively, coupled to said receiver means from track section; detection means, coupled to said receiver means, for detecting variations in said first and second electrical signals; means for indicating the presence of a car within said track section as a function of the variations in said first and second electrical signals; a pair of transmitter track coupling inductor circuits; and means for applying the output signals from said pair of oscillators in an electrical parallel arrangement to said pair of transmitter coupling inductor circuits.
Claim 3
Dependent Claim
36 words
The apparatus of claim 1 wherein each of said transmitter track coupling inductor circuits including separate circuit means for operating each of said inductor circuits at approximately series resonance for a different one of said frequencies.
Claim 4
Dependent Claim
49 words
The apparatus of claim 1 wherein said means for applying the output signals includes a pair of transformers with each transformer having a primary winding excited by energy at a different one of said frequencies, and a secondary winding series coupled with the secondary winding of the other transformer.
Claim 5
Dependent Claim
16 words
The apparatus of claim 3 wherein one of said secondary windings is shunted by a capacitor.
Claim 6
Dependent Claim
52 words
The apparatus of claim 1 further including a pair of receiver track coupling inductor circuits; and wherein said receiver means including means for applying the output signals from each of said receiver track coupling inductor circuits in an electrical parallEl arrangement to separate circuits for providing the first and second electrical signals.
Claim 7
Dependent Claim
51 words
The apparatus of claim 1 including a pair of receiver track coupling inductor circuits; and wherein said receiver means including means for applying the output signals from each of said receiver track coupling inductor circuits in an electrical parallel arrangement to separate circuits for providing the first and second electrical signals.
Claim 8
Independent Claim
165 words
An apparatus for detecting the presence of a car within a section of railway track, said apparatus including: transmitter means for coupling electrical energy at first and second frequencies to said track section; receiver means for providing first and second electrical signals representative of the electrical energy at said first and second frequencies, respectively, coupled to said receiver means from said track section; track coupling inductor circuits, said transmitter and said receiver means being inductively coupled to said track section by different track coupling inductor circuits, said track coupling inductor circuits each including a different pair of inductors disposed at opposite end sections of said track section substantially equidistant between the rails of said track section; detector means, responsive to said first and second electrical signals for detecting variations in said first and second signals; and, means, coupled to said detector means, for indicating the presence of a car within said section as a function of variations in either said first or second electrical signals.
Claim 9
Independent Claim
165 words
An apparatus for detecting the presence of a car within a section of railway track, said apparatus including: transmitter means for coupling electrical energy at first and second frequencies to said track section; receiver means for providing first and second electrical signals representative of the electrical energy at said first and second frequencies, respectively, coupled to said receiver means from said track section; track coupling inductor circuits, said transmitter and said receiver means being inductively coupled to said track section by different track coupling inductor circuits, said track coupling inductor circuits each including a different pair of inductors disposed at opposite end sections of said track section substantially equidistant between the rails of said track section; detector means, responsive to said first and second electrical signals for detecting variations in said first and second signals; and, means, coupled to said detector means, for indicating the presence of a car within said section as a function of variations in either said first or second electrical signals.
Claim 10
Dependent Claim
32 words
The apparatus of claim 7 wherein said transmitter means includes means for generating said first frequency at a frequency below 20,000 Hz and said second frequency at a frequency above 50,000 Hz.
Claim 11
Dependent Claim
30 words
The apparatus of claim 8 wherein said coupling inductor circuits each including a separate coil wrapped metallic core inductor located in the roadbed at opposite ends of said track section.
Claim 12
Dependent Claim
27 words
The apparatus of claim 8 wherein said coupling inductor circuits each including a separate air core inductor positioned approximately equidistant between the rails within said track section.
Claim 13
Dependent Claim
22 words
The apparatus of claim 8 wherein said track coupling inductor circuits each including means for operating at approximately a series resonance condition.
Claim 14
Dependent Claim
23 words
The apparatus of claim 8 wherein said track coupling inductor circuits each including means for operating at approximately a parallel tuned anti-resonance condition.
Claim 15
Dependent Claim
28 words
The device of claim 8 wherein the track section includes a track switch and further comprises connection means for providing low impedance electrical continuity through the track switch.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-08 | 1976-02-07 | 1976-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-08 | 1980-02-07 | 1980-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-08 | 1984-02-07 | 1984-08-08 | $7700.00 | Window Closed / Lapsed |