Railway wheel counter and block control systems

• US 6,371,417 B1
• Filed: 05/22/2000
• Issued: 04/16/2002
• Est. Priority Date: 09/04/1997
• Status: Expired due to Term

• Current Assignee: Siemens Industry Incorporated (Siemens AG)
• Original Assignee: LB Foster Company A Pennsylvania Corporation
• Inventors: Southon, Brian Neil
• Primary Examiner(s): Le, Mark T.
• Application Number:
  US09/486,947
• Time in Patent Office: 694 Days
• Field of Search: 246/122.R, 246/124, 246/247, 246/249, 246/270.R, 246/359, 246/360, 246/473.R, 246/478, 246/246, 324/200, 324/207.13, 324/207.15, 324/207.16, 324/207.22, 324/225, 324/257, 324/259, 324/179
• US Class Current: 246/247
• CPC Class Codes: B61L 1/165 Electrical
• CPC Class Codes: B61L 1/168 Specific transmission details
• CPC Class Codes: B61L 1/169 Diagnosis
• CPC Class Codes: B61L 29/284 using rail-contacts, rail microphones, or the like, controlled by the vehicle

Abstract

Railway wheel detection and counter and block control systems are disclosed using magnetic coils to detect wheels via measuring eddy current losses induced by a railway wheel as it disturbs the coil'"'"'s magnetic field. Information from the coils is measured and processed using combination of analog and digital signal processing which processing automatically tests and calibrates all components to provide fail-safe operation. Virtual blocks are used to establish train presence, speed, and direction which parameters are used to provide block control systems.

Claims

1. A railway vehicle detector for sensing a passing railway vehicle wheel travelling along an elongated rail connectable to a processing means, said detector comprising:

a. means for supplying an alternating current having a preselected frequency;

b. at least one wheel sensing element, including a resonant tank circuit having a resonant frequency, excitable by said alternating current, said tank circuit being arranged for producing a voltage change as said wheel is travelling adjacent said at least one wheel sensing element due to a change in the effective inductance in said tank circuit as the wheel passes;

c. the at least one wheel sensing element being connectable to the processing means for receiving said voltage change and responsively producing an output signal indicative of the presence of said wheel,

wherein said preselected frequency is proportional to the resonant frequency of the tank circuit, and further wherein said preselected frequency is the frequency required to operate the tank circuit at a voltage approximately equal to a range between one half of the voltage across the tank circuit when operated at the circuit'"'"'s resonant frequency and the voltage across the tank circuit when operated at the circuit'"'"'s resonant frequency.

2. A railway vehicle detector as described in claim 1, wherein said preselected frequency is the frequency required to operate the tank circuit at a voltage approximately equal to one half of the voltage across the tank circuit when operated at the circuit'"'"'s resonant frequency.

3. A railway vehicle detector as described in claim 1, further comprising a rail sensing element configured to indicate the proximity of said detector to said rail being greater than a preselected distance.

4. A railway vehicle detector as described in claim 3, wherein said preselected distance is 2 inches.

5. A railway vehicle detector as described in claim 3, wherein said rail sensing element comprises a resonant tank circuit.

6. A railway vehicle detector as described in claim 5, wherein the resonant tank circuit of the rail sensing element is arranged for producing a voltage change as said detector is moved in relation to said rail, and further being connectable to a processing means for receiving said voltage changes and responsively producing an output signal indicative of the proximity of said detector to said rail within a preselected range.

7. A railway wheel vehicle detector as described in claim 1, wherein said resonant tank circuit of said at least one wheel sensing element is connected in a multiple terminal electrical network comprised of;

a. a primary coil connected between a first and second network terminal; and

b. a capacitor connected between the first and second network terminal.

8. A railway vehicle detector as described in claim 1, wherein the at least one wheel sensing element is a first wheel sensing element and further comprising a second wheel sensing element in longitudinal spaced relation to the first wheel sensing element, each being connectable to the processing means for receiving the voltage changes from the circuit of each wheel sensing element and responsively producing an output signal indicative of the presence, speed, direction and wheel count of said wheel.

9. A railway wheel vehicle detector as described in claim 8 wherein the tank circuit of the first and second wheel sensing elements are in turn series connected in a multiple terminal electrical network comprised of;

a. a first coil connected between a first and second network terminal;

b. a first capacitor connected across the first and second network terminal;

c. a second coil across the second and a third network terminal; and

d. a second capacitor across the second and third network terminal;

and wherein the first coil and the first capacitor comprise said resonant tank circuit of said first wheel sensing element and the second coil and the second capacitor comprise said resonant tank circuit of said second wheel sensing element.

10. A railway vehicle detector as described in claim 3, wherein the wheel sensing element is positioned to detect the movement of said wheel along the elongated rail and wherein the rail sensing element is positioned to indicated the proximity to said rail such that both the wheel and the rail are sensed independently and without interaction.

11. A railway vehicle detector as described in claim 9, wherein excitation by said alternating current will produce a steady state voltage drop across the said network at the preselected frequency of each excited tank circuit without appreciable voltage generated across the other tank circuit not in resonance such that each circuit can be separately excited and sensed without interaction from the circuit.

12. A railway vehicle detector as described in claim 9, wherein the first and second wheel sensing elements are mounted on said elongated rail and produce various said voltage fluctuations when said wheel is travelling in a forward direction and a second variation pattern when said wheel is travelling in a reverse direction.

13. A railway vehicle detector as described in claim 8, wherein the longitudinal displacement between the first and second wheel sensing elements is in a range of 8 to 36 inches.

14. A railway vehicle detector as described in claims 13, wherein the longitudinal displacement is generally 12 inches.

15. A railway vehicle detector as described in claim 1, wherein said means for supplying an alternating current is a Numerically Controlled Oscillator.

16. A railway vehicle detector as described in claim 1, wherein said processing means includes digital and analog processing such that calibration is automatic and adjustment free over an extended temperature range and life of the detector.

17. A railway vehicle detector as described in claim 1, wherein said processing means includes digital and analog processing such that components are configurable in a plurality of separate closed loop feedback paths thereby providing a means for feedback loop self-testing.

18. A railway vehicle detector as described in claim 17, wherein said processing means includes an amplifier for removal of a DC offset and amplification of steady state voltage fluctuations caused by said wheel.

19. A railway vehicle detector as described in claim 8, wherein said processing means includes level detection for detecting said wheel adjacent said first wheel sensing element and for detecting said wheel adjacent the second wheel sensing element.

20. A railway vehicle detector as described in claim 19, wherein said processing means includes a level detector for producing a logic output when said first or second wheel sensing elements produce signal patterns indicating metallic objects other than said wheel.

21. A railway vehicle detector as described in claim 20, wherein logic circuits produce a first output signal indicating forward movement of said wheel and a second output signal indicating movement of said wheel in a reverse direction, thereby detecting a direction.

22. A railway vehicle detector as described in claim 21 wherein said logic circuits differentiate forward and reverse movement of said wheel along said elongated rail such that wheel detection and the direction determination is accurate during any dead slow wheel reversal over the detector.

23. A railway vehicle detector as described in claim 22, wherein said logic circuits produce output signals in the form of a numerical output corresponding to a number of wheels passed by the detector.

24. A railway vehicle detector as described in claim 23, wherein said logic circuits produce output signals such that any and all deviations from normal operation will cause a fail-safe output action.