Patent Application
20110006167
1. Field of the Invention
The present invention relates to a fail-safe safety system to detect and annunciate fractured running rails in electrically propelled transit systems without the need to induce block by block communication signals, using block transmitters and receivers, currently required by existing systems for detecting occupancy, transmitting speed commands, and detecting broken running rails. Additionally, unlike existing systems, the present invention can detect running rail fractures that are not completely broken and bidirectionally communicate control operating parameters and the location of the fracture over existing propulsion power lines.
2. Discussion of Background
With the advent of Computer Based Train Control (CBTC) systems that use moving blocks existing fixed block rapid transit systems operating on running rails such as the Bay Area's Rapid Transit Districts, BART, and Municipal Railway, MUNI, in San Francisco Calif. it is imperative that we develop a system to detect and annunciate broken or fractured running rails.
It has been, and still is, an ongoing problem detecting, and annunciating, a fractured running rail with CBTC systems because in these systems there are no, as in fixed block systems, individual block signaling currents that detect and annunciate a broken running rail.
Further exasperating the problem is the present lack of communication lines from wayside to communicate fractured running rail information to a central location that can control train movement. These leading areas of concern, coupled with projected costs and time to implement a solution, have caused transit agencies to avoid upgrading their fixed block systems to CBTC that can, and would, substantially increase passenger throughput and reduce commute times.
Because the primary concern of any mass transit system is to avoid conflict between safety and the transit systems desire to move the maximum number of passengers from point A to point B, in the shortest period of time, with the highest degree of operating reliability it is imperative that any proposed system be fail-safe and in concord with these seemingly incompatible, opposing, and contradictory objectives.
Today the vast majority of existing rapid transit systems regulate the speed of trains by using duel mode block by block track signaling and occupancy detecting systems built into the running rail tracks and controlled by wayside Automatic Train Control (ATC) systems. These systems transmit predetermined speed commands to the trains, as a function of track occupancy, grade, and position, to the front of the train in essence pulling it along. Train detection, or detection and annunciation of broken running rails, are both accomplished by removing these speed commands using either the train's wheels to short out, or by a broken running rail, that in essence removes the signals normally received by occupancy detection track receivers that are physically located behind the train—indicating an occupancy.
There have been numerous patents to detect and annunciate fractured running rails most notably by Grappone, U.S. Pat. No. 6,655,639, Gauthier U.S. Pat. No. 5,680,054, Frielinghaus, U.S. Pat. No. 4,886,226, Petit, et al. U.S. Pat. No. 4,728,063, Kuhn, U.S. Pat. No. 4,306,694, and Stark et al. U.S. Pat. No. 4,117,529. Virtually all of these induce signals into the running rails, can only detect completely broken rails, and use a unidirectional hard wired, or radio frequency, communications link that only transmits information and is, more importantly, not fail-safe.
In order to resolve these concerns in a timely and cost-effective manner a solution must be found that: is compatible with the existing system, does not require inducing signals into the running rails, can detect fractures in rails that are not complete fractures, has bidirectional communications that can communicate over existing propulsion power lines and above all is fail-safe without sacrificing operating reliability and throughput—all of which this present invention, as follows, uniquely satisfies.
Accordingly the major factors associated with the detection and annunciation of fractured rails, already briefly recited, the present invention provides a simple means for the long-felt need to detect and annunciate fractures in running rails of CBTC systems in a fail-safe manner. The core of the invention is detecting an unbalance in propulsion currents in the ground returns provided by the two running rails with, or without, automatic train controls, and communicate this imbalance in a fail-safe manner to a central location—indicating a fracture. The invention measures and compares electrical propulsion currents in existing running rail returns and communicates this information, in a fail-safe manner, over existing propulsion power lines using commercially available power line communications (PLC) equipment to a central controller location.
It is normal operating practice in transit systems operating electrically propelled transit vehicles to physically partition multiple sections of tracks to allocate a multiplicity of power sources. This is so traction power requirements are distributed among these sources and in addition to provide for alternate, and/or redundant sources of power, in the advent of failure of any one power source. By virtue of this physical partitioning detection of an unbalance in leakage or running rail traction power, such as a fracture in a running rail, a physical location can be determined either on site or at a central controller location.
Bi-directional communication from wayside to a central location in a fail-safe manner is uniquely accomplished using proven and commercially available Power Line Communications (PLC) technology communicating over propulsion power lines. By virtue of this no additional communication cabling is required and the exact zone location of the fractured rail can be communicated.
In the interest of brevity, and not to obfuscate the essence of this application, features of the invention that are readily apparent to those skilled in the art have not been delineated in detail here but are mentioned for those without that expertise. Implicit, owing to the bidirectional nature of the communications controllers and power line communicators operating parameters of the system are easily reconfigured and resolution of detection within zones can be increased by adding more transducers, communications controllers and power line communications. In addition, the transit vehicle itself may receive and communicate with central and wayside by simply having on board power line communications.
Other features, and their advantages, of this system will be apparent to those skilled in the art of running rail fracture detection and annunciation from a careful reading of the Detailed Description of Preferred Embodiments accompanied by the following drawings.
In the drawings,
The present invention relates to a fail-safe safety system to detect and annunciate fractured running rails in electrically propelled transit systems. The system is designed as a fail-safe, fault tolerant, and self annunciating system in that if any component, or connection, of the system fails, or is out of tolerance, it is immediately communicated to a central location. Additionally, unlike existing systems, the present invention does not require, or interfere with, automatic train controls and uses the propulsion power bus, itself fail-safe, as a means of bidirectional communication without additional cabling.
As shown current transducer 100 detects running rail current I1 and current transducer 200 detects running rail current I2 of zone 1—of a multiple (N zone) system. Note: that in normal operation, without a fracture, 600 in zone 1, running rail current I1 and running rail current I2 are, within a known margin of error, equal. The magnitudes of I1 and I2 are sent to the bidirectional communications controller 300 and communicated to Power Line Communications (PLC) device 400.
Central control, 500, physically located at the train control center polls power line communicators 400, processes and interfaces with train control computers and displays. Whenever an unbalance, or a complete absence, between running rail track currents I1 or I2 exists central control electronics alarms and displays this information on train control displays.
Under software, and operator, control central computer, 450, queries central communications controller, 325, that in turn queries power line communications, 400, for the integrity of the running rails as shown in
As shown in
In turn this information is translated into a pictorial visual presentation by display, 550, of
It is readily apparent to those skilled in the art of detection and annunciation of fractured running rails, especially in electrically propelled rapid transit systems, from reading the foregoing that many substitutions and modifications, including but not limited to, using transit running rails to monitor propulsion currents and propulsion power lines to communicate this information may be made to the preferred embodiments described without departing from the spirit and scope of the present invention.
