Patent Application
20090173842
This invention relates generally to railroad systems, and more specifically, to methods and system of automatically calibrating track circuits.
A rail track circuit typically is used to detect whether a train is present on a track section. Such circuit also can be used to detect broken rails within the track section and/or can be used to transmit signal aspect information through the rails. A typical track circuit includes rails in electrical series with a signal transmitter and a signal receiver. The signal transmitter applies a voltage, sometimes referred to as a transmit voltage, to the rails. As a result, a current signal, sometimes referred to as a receive current, is transmitted through the rails. The receive current is detected by the receiver.
When a train composed of one or multiple railcars is located on the track section of the track circuit, the wheels of the railcars act as a shunt between the rails and form a shunt path. The shunt path creates an electrical short between the rails at the location of the train, and such short path effectively prevents the receive current from being received/detected by the signal receiver.
Over time, environmental conditions and rail conditions can change. These changing conditions impact ballast resistance of the track circuit. Generally, leakage paths occur through the ballast, and the leakage resistance of such paths varies due to the changing conditions. The varying leakage resistance impacts the receive current. The track circuit therefore is configured, or calibrated, to operate over a range of ballast resistance.
Due to the changing conditions, over time, the track circuit may require re-calibration. Known calibration techniques involve positioning human “maintainers” with two-way radios at the transmitter and receiver. The maintainer at the transmitter communicates data related to the applied voltage to the maintainer at the receiver. The receiver maintainer then informs the transmitter maintainer of the current signal received at the receiver. Adjustments are made to both the transmitter and receiver so that the track circuit operates as desired over the ballast resistance range. Another known calibration technique is for a single human maintainer to perform track circuit calibration by traveling between transmitter and receiver sites (i.e., locations) to make each adjustment. As such, the process of manually calibrating the track circuit settings may be costly, inefficient and/or time-consuming.
In one aspect, a method for calibrating a track circuit is provided. The track circuit includes a transmit processing unit, a receive processing unit, and a plurality of rails coupled in series to form a track section having a first end and a second end. The transmit processing unit is coupled to the track section adjacent the first end. The receive processing unit is coupled to the track section adjacent the second end. The method includes operating the transmit processing unit so that a first voltage is applied to the track section, operating the receive processing unit to detect a first current signal, and if a parameter of the first current signal is not within a predetermined acceptable range, then communicating with the transmit processing unit so that the transmit processing unit applies a second voltage to the track section, the second voltage having a different magnitude than the first voltage.
In a further aspect, a track circuit is provided. The track circuit includes a remote system, a transmit processing unit, and a receive processing unit. The remote system is configured to electronically couple to at least one of the transmit processing unit and the receive processing unit. The track circuit further includes a plurality of rails coupled in series to form a track section having a first end and a second end. The transmit processing unit coupled to the track section adjacent the first end. The receive processing unit coupled to the track section adjacent the second end. The transmit processing unit is configured to apply a first voltage to the track section during operation. The receive processing unit is configured to detect a first current signal during operation. If a parameter of the first current signal is not within a predetermined acceptable range, then the receive processing unit is configured to communicate with the transmit processing unit such that the transmit processing unit applies a second voltage to the track section. The second voltage has a different magnitude than the first voltage.
In another aspect, a track circuit is provided. The track circuit includes a transmit processing unit, a receive processing unit, and a plurality of rails coupled in series to form a track section having a first end and a second end. The transmit processing unit is coupled to the track section adjacent the first end. The receive processing unit coupled to the track section adjacent the second end. The transmit processing unit is configured to apply a first voltage to the track section during operation, and the receive processing unit is configured to detect a first current signal during operation. If a parameter of the first current signal is not within a predetermined acceptable range, then the receive processing unit is configured to communicate with the transmit processing unit such that the transmit processing unit applies a second voltage to the track section. The second voltage has a different magnitude than the first voltage.
Track circuit 100 further includes a transmit processing unit 103 and a receive processing unit 105. In the exemplary embodiment, adjustments are made to both units 103 and 105 so that track circuit 100 operates as desired over a given ballast resistance range. In the exemplary embodiment, transmit processing unit 103 is coupled to adjacent track section first end 16, and receive processing unit 105 is coupled to adjacent track section second end 18. Transmit processing unit 103 is configured to apply a first voltage across track section 101 during operation. For example, transmit processing unit 103 may be configured to apply a voltage across track section 101 at end 16, thereby generating a current in a direction shown in
In the exemplary embodiment, transmit processing unit 103 includes at least one energy source 110 and at least one receiver 116, and receive processing unit 105 includes at least one energy source 112 and at least one receiver 114. Moreover, in the exemplary embodiment, each unit 103 and unit 105 includes at least one program including at least one arithmetic logic unit. In an alternative embodiment, each unit 103 and unit 105 does not include at least one arithmetic logic unit. Generally, each unit 103 and 105 of a coded track circuit includes arithmetic logic units, and each unit 103 and 105 of a non-coded track circuit does not include arithmetic logic units. For example, non-coded track circuit units have only an on or off current detection. With an on or off current detections, the on or off transmit voltage needs to be high enough to allow current detection.
In the exemplary embodiment, computer programs, or software, are stored in memory device 206 within unit 103 and/or unit 105. A suitable memory device 206 in the preferred embodiment is an electrically erasable programmable read only member (hereinafter “EEPROM”). Moreover, it is understood that other types of memory could be utilized, such as simple read only memory (ROM), or programmable read only member (PROM), or, if the ability to reprogram the ROM is desirable, erasable programmable read only memory (EPROM), which are conventionally erased by exposure to ultraviolet light or FLASH memory.
Track circuit 100 may be calibrated, operated, and monitored from a remote location. For example, in one embodiment, transmit and receive processing units 103 and 105 are configured to communicate with a remote system (not shown) via a wireless network. In the exemplary embodiment, communication between the remote system and units 103 and 105 is based on a client-server relationship using established protocols such as, but not limited to, Internet Protocol (IP). In an alternative embodiment, communication between the remote system and units 103 and 105 may include any suitable means that enables track circuit 100 to function as described herein.
In the exemplary embodiment, unit 103 is configured to apply 202 a voltage 203 across track section 101, and unit 105 is configured to detect 205 a current 204 flowing through track section 101. In an alternative embodiment, the track section 101 is calibrated in a substantially similar matter to the method described herein; however, unit 105 is configured to apply 202 voltage 203 across track section 101, and unit 103 is configured to detect current 204 flowing through track section 101.
Moreover, in the exemplary embodiment, at least one unit 103 and/or unit 105 includes memory device 206 for at least temporarily storing various voltage and current parameters and a predetermined current threshold range. For example, the transmit voltage may be approximately 2 volts while the receive current parameter may be approximately 1.5 amps and the threshold range may be set at approximately 0.5 amps. The predetermined current threshold range 223 may be input as a suggested threshold by the maintainer. In the exemplary embodiment, the predetermined current threshold range 223 is approximately 0.5-6.0 amps. In an alternative embodiment, the predetermined current threshold range 223 is pre-programmed within unit 105.
In the exemplary embodiment, unit 105 is configured to adjust 208 the range 223 based upon the changing ballast condition. For example, if the track circuit is set up by the maintainer when the ballast leakage is low (i.e., good conduction down the rail), then the transmit voltage may be set to approximately 1 volt and the receive current may be approximately 2 amps. For example, if a train is detected in the track circuit, the train shorts the rails in the track circuit causing a small amount of current to be received at unit 105 (i.e. receiver). As such, the threshold could be set to approximately 0.6 amps such that if the receive current is below 0.6 amps, the track circuit will declare that a train is on the track circuit. However, if the ballast leakage increases (i.e. low conduction down the rail exists), then the receive current will be less due to the ballast leakage. Therefore, if the receive current drops below 0.6 amps at unit 105 (i.e. receiver), a train is “detected” on the track circuit due to the ballast conditions even though no train actually occupies the track. As such, range 223 is adjusted based upon the changing ballast conditions.
Once current threshold range 223 has been adjusted based upon the ballast conditions, unit 105 is configured to apply 212 the magnitude of range 223 and the parameters of signal 204 across track section 101, and unit 103 is configured to detect 214 the magnitude of range 223 and signal 204 flowing through track section 101.
In the exemplary embodiment, at least one of unit 103 and/or unit 105 also includes a logic module 220 including a function block 222. Function block 222 within unit 103 is configured to compare 216 at least one parameter of a detected current signal to the current threshold range 223.
After comparison of a parameter of current signal 204 to current threshold range 223, if a parameter of current signal 204 is not within the range, then unit 103 is configured to automatically adjust 225 voltage 203 and unit 103 is configured to apply a second voltage across track section 101. In the exemplary embodiment, the second voltage has a different magnitude than the first voltage 203, and the method, described herein, repeats until a predetermined parameter of current signal 204 is within the range 223.
On the other hand, after comparison of a parameter of current signal 204 to current threshold range 223, if current signal 204 is within the range 223, then unit 105 is configured to communicate with unit 103 such that unit 103 maintains the magnitude of first voltage signal 203. Moreover, in the exemplary embodiment, if current signal 204 is within range 223, then unit 105 is configured to communicate with unit 103 such that unit 103 records first voltage signal 203 parameters, first current signal 204 parameters, and current threshold range 223 parameters.
In the exemplary embodiment, a timing mechanism (not shown) is coupled to each unit 103 and 105. The timing mechanism is configured to switch each respective unit 103 and 105 to the operational mode after a predetermined time to prevent units 103 and 105 from remaining in calibration mode 199. For example, unit 103 and/or 105 would switch from calibration mode 199 to the operational mode after approximately 1 minute of inactivity in calibration mode 199. The default for switching out of calibration mode 199 may be to a safe default value or to the pre-determined values. In an alternative embodiment, once track section 101 has been calibrated, then the maintainer may return each unit 103 and/or 105 to the operational mode. Moreover, at least one unit 103 and/or 105 may be coupled to an output display (not shown) such that various stored parameters may be output to the display.
During operation, in the exemplary embodiment, the maintainer sets transmit processing unit 103 to local calibration mode 199 to begin 201 automatic calibration of track section 101. In calibration mode 199, unit 103 applies 202 a first voltage signal 203 (i.e., test pulses) across track section 101. In an alternative embodiment, signal 203 is transmitted from unit 103 as a predefined pulse pattern, a message, and/or any other communication media that enables track circuit 100 to function as described herein.
In the exemplary embodiment, unit 105 detects 205 first current signal 204. In the exemplary embodiment, unit 105 at least temporarily stores the parameters of signal 203 and range 223 in memory device 206. In the exemplary embodiment, unit 105 may adjust 208 the range 223 based upon changing ballast conditions.
In the exemplary embodiment, unit 105 adjusts 208 the range 223 based upon the changing ballast condition. For example, if the track circuit is set up by the maintainer when the ballast leakage is low (i.e., good conduction down the rail), then the transmit voltage may be set to approximately 1 volt and the receive current may be approximately 2 amps. For example, if a train is detected in the track circuit, the train shorts the rails in the track circuit causing a small amount of current to be received at unit 105 (i.e. receiver). As such, the threshold could be set to approximately 0.6 amps such that if the receive current is below 0.6 amps, the track circuit will declare that a train is on the track circuit. However, if the ballast leakage increases (i.e. low conduction down the rail exists), then the receive current will be less due to the ballast leakage. Therefore, if the receive current drops below 0.6 amps at unit 105 (i.e. receiver), a train is “detected” on the track circuit due to the ballast conditions even though no train actually occupies the track. As such, range 223 is adjusted based upon the changing ballast conditions.
Once current threshold range 223 has been adjusted based upon the ballast conditions, unit 105 applies 212 the magnitude of range 223 and the parameters of signal 204 across track section 101, and unit 103 detects 214 the magnitude of range 223 and signal 204 flowing through track section 101.
Function block 222 within unit 103 then compares 216 at least one parameter of signal 204 to the current threshold range 223. In the exemplary embodiment, after comparison of a parameter of current signal 204 to current threshold range 223, if a parameter of first current signal 204 is not within the current threshold range 223, then unit 103 automatically adjusts 225 first voltage 203 to a second voltage. Specifically, in the exemplary embodiment, second voltage has a different magnitude than first voltage signal 203. Unit 103 then applies 202 the second voltage across track section 101. As such, unit 105 detects a second current, and the method repeats until a predetermined parameter of the current signal is within the range.
On the other hand, if after comparison of a parameter of current signal 204 to current threshold range 223, the parameter current signal 204 is within the range, then unit 103 maintains the magnitude of first voltage signal 203. Moreover, in the exemplary embodiment, if current signal 204 is within range 223, then unit 103 records 218 first voltage signal 203 parameters, first current signal 204 parameters, and current threshold range 223 parameters. Calibration of track section 101 is complete 219 when the various parameters have been recorded by unit 103.
In the exemplary embodiment, when calibration of track section 101 is complete, the timing mechanism (not shown) switches each respective unit 103 and 105 to the operational mode after a predetermined time to prevent units 103 and 105 from remaining in calibration mode 199. For example, unit 103 and/or 105 would switch from calibration mode 199 to the operational mode after approximately 1 minute of inactivity in calibration mode 199. The default for switching out of calibration mode 199 may be to a safe default value or to the pre-determined values. In an alternative embodiment, once track section 101 has been calibrated, then the maintainer may return each unit 103 and/or 105 to the operational mode. Moreover, at least one unit 103 and/or 105 may be coupled to an output display (not shown) such that various stored parameters may be output to the display.
In the exemplary embodiment, the remote system is configured to apply 299 a signal to unit 103 instructing unit 103 to operate in calibration mode 301, and unit 103 is configured to detect 302 the signal from the remove system. In the exemplary embodiment, unit 103 is configured to apply 307 a start-up signal 304 across track section 101. Unit 105 is configured to detect signal 304 and is configured to begin 309 automatic calibration of track section 101. As such, unit 105 is configured to apply 313 a voltage signal 305 across track section 101, and unit 103 is configured to detect 312 a current signal 306 flowing through track section 101. In an alternative embodiment, the remote system is configured to apply a signal to track section 101 instructing unit 105 to operate in calibration mode 301. As such, the track section 101 is calibrated in a substantially similar matter to the method described herein.
In the exemplary embodiment, at least one of unit 103 and/or unit 105 includes a memory device 206 for at least temporarily storing various parameters and a current threshold range. The current threshold range 303 may be input into unit 103 as a suggested threshold by the maintainer. In an alternative embodiment, the current threshold range 303 is pre-programmed within unit 103. In the exemplary embodiment, unit 103 is configured to adjust the range 303 based upon changing ballast conditions. For example, if the track circuit is set up by the maintainer when the ballast leakage is low (i.e., good conduction down the rail), then the transmit voltage may be set to approximately 1 volt and the receive current may be approximately 2 amps. For example, if a train is detected in the track circuit, the train shorts the rails in the track circuit causing a small amount of current to be received at the receiver unit. As such, the threshold could be set to approximately 0.6 amps such that if the receive current is below 0.6 amps, the track circuit will declare that a train is on the track circuit. However, if the ballast leakage increases (i.e. low conduction down the rail exists), then the receive current will be less due to the ballast leakage. Therefore, if the receive current drops below 0.6 amps at the receiver unit, a train is “detected” on the track circuit due to the ballast conditions even though no train actually occupies the track. As such, range 303 is adjusted based upon the changing ballast conditions.
Once current threshold range 303 has been adjusted based upon the ballast conditions, unit 105 is configured to apply 316 the magnitude of range 303 and the parameters of signal 305 across track section 101, and unit 103 is configured to detect 318 the magnitude of range 303 and signal 305 flowing through track section 101.
In the exemplary embodiment, at least one of unit 103 and/or unit 105 also includes a logic module 220 including a function block 222. Function block 222 within unit 105 is configured to compare at least one parameter of a detected signal to a threshold range. After comparison of a parameter of current signal 306 to current threshold range 303, if a parameter of current signal 306 is not within the range, then unit 105 is configured to apply a second voltage across track section 101. In the exemplary embodiment, the second voltage has a different magnitude than the first voltage 305, and the method, described herein, repeats until a predetermined parameter of current signal 306 is within the range 303.
On the other hand, after comparison of a parameter of current signal 306 to predetermined current threshold range 303, if a parameter of current signal 306 is within the range, then unit 105 maintains the magnitude of first voltage signal 305. Moreover, in the exemplary embodiment, if current signal 306 is within range 303, then unit 105 communicates with unit 103 such that unit 103 records first voltage signal 305 parameters, first current signal 306 parameters, and current threshold range 303 parameters.
In the exemplary embodiment, a timing mechanism (not shown) is coupled to at least one unit 103 and/or 105. Once unit 103 records first voltage signal 305 parameters, first current signal 306 parameters, and current threshold range 303 parameters, calibration is substantially complete, and the remote system is configured to apply a signal to the timing mechanism. The signal is configured to switch the timing mechanism from calibration mode 301 to the operational mode to prevent units 103 and 105 from remaining in calibration mode 301. In an alternative embodiment, each timing mechanism is configured to switch from calibration mode 301 to the operational mode after a predetermined time to prevent units 103 and 105 from remaining in calibration mode 301. In a further alternative embodiment, once track section 101 has been calibrated, then the maintainer may return each unit 103 and/or 105 to the operational mode. Moreover, at least one unit 103 and/or 105 may be coupled to an output display (not shown) such that various stored parameters may be output to the display.
During operation, in the exemplary embodiment, the remote system applies 299 a signal to unit 103 instructing unit 103 to operate in calibration mode 301, and unit 103 detects 302 the signal. In the exemplary embodiment, unit 103 communicates with unit 105 such that unit 105 applies 307 a start-up signal across track section 101 to begin calibration of track section 101. In the exemplary embodiment, in calibration mode 301, unit 103 applies 307 a start-up signal 304 to unit 105. Start-up signal 304 instructs unit 105 to begin calibration or re-calibration of track section 101, and unit 105 begins 309 calibration or re-calibration. In the exemplary embodiment, unit 105 applies 313 first voltage signal 305 across track section 101. In an alternative embodiment, signal 305 is applied across track section 101 as a predefined pulse pattern, a message, and/or any other communication media that enables track circuit 100 to function as described herein.
In the exemplary embodiment, unit 103 detects 312 a first current signal 306. In the exemplary embodiment, unit 103 at least temporarily stores the parameters of current signal 306 in memory device 206. In the exemplary embodiment, unit 103 adjusts 314 the range 303 based upon the changes in the condition of the ballast described herein above. When a train enters a track circuit, the received current drops suddenly and is, therefore, distinguishable from ballast deterioration which causes the receive current to drop much more slowly.
For example, if the track circuit is set up by the maintainer when the ballast leakage is low (i.e., good conduction down the rail), then the transmit voltage may be set to approximately 1 volt and the receive current may be approximately 2 amps. For example, if a train is detected in the track circuit, the train shorts the rails in the track circuit causing a small amount of current to be received at the receiver unit. As such, the threshold could be set to approximately 0.6 amps such that if the receive current is below 0.6 amps, the track circuit will declare that a train is on the track circuit. However, if the ballast leakage increases (i.e. low conduction down the rail exists), then the receive current will be less due to the ballast leakage. Therefore, if the receive current drops below 0.6 amps at the receiver unit, a train is “detected” on the track circuit due to the ballast conditions even though no train actually occupies the track. As such, range 303 is adjusted based upon the changing ballast conditions.
Once range 303 has been adjusted, unit 105 applies 316 the magnitude of the parameters signal 305 across track section 101 such that unit 103 detects 318 the magnitude of the parameters of signal 305.
Function block 222 within unit 105 compares 320 at least one parameter of current signal 306 to the current threshold range 303. In the exemplary embodiment, after comparison of a parameter of current signal 306 to predetermined current threshold range 303, if a parameter of current signal 306 is not within the predetermined current threshold range 303, then unit 105 automatically adjusts 321 voltage 305 and applies 313 a second voltage across track section 101. Specifically, in the exemplary embodiment, second voltage has a different magnitude than first voltage 305. As such, unit 103 detects a second current, and the method repeats until a predetermined parameter of current signal 306 is within the range 303.
On the other hand, if after comparison of a parameter of first current signal 306 is within the predetermined current threshold range 303, the parameter current signal 306 is within the range, then unit 105 maintains the magnitude of first voltage signal 305. Moreover, in the exemplary embodiment, if current signal 306 is within range 303, then unit 105 communicates with unit 103 such that unit 103 records 322 first voltage signal 305 parameters, first current signal 306 parameters, and current threshold range 303 parameters within memory device 206.
Calibration of track section 101 is complete 324 when the various parameters have been recorded by unit 103. In the exemplary embodiment, once track section 101 is complete, the remote system communicates with at least one of the timing mechanisms (not shown) coupled to unit 103 and/or unit 105 such that the remote system instructs the timing mechanism to switch each respective unit 103 and/or 105 to the operational mode from calibration mode 301 to prevent units 103 and/or 105 from remaining in calibration mode 301. In an alternative embodiment, each timing mechanism switches from calibration mode 301 to the operational mode after a predetermined time to prevent units 103 and 105 from remaining in calibration mode 301. In a further alternative embodiment, once track section 101 has been calibrated, then the maintainer may return each unit 103 and/or 105 to the operational mode. Moreover, at least one unit 103 and/or 105 is coupled to an output display (not shown) such that various stored parameters are output to the display.
The above-described methods and systems enable automatic calibration of the transmitting voltage and the receiving current thresholds for a track circuit of a railroad. Track circuit calibration may be required when the environment changes and/or when the railroad conditions change. Accordingly, the need for manual setup and calibration is eliminated, thereby facilitating a reduction in the chance for error, in costs and/or time associated with maintenance of the railroad. Moreover, the above-described methods and system increase the safety of the railroad.
At least one unit 103 and/or 105 may include, but is not limited to including, a microprocessor, microcontroller, a microcomputer, a programmable logic controller, an application specific integrated circuit, or any other programmable circuit. Therefore, the term processor, as used herein, is not limited to just those integrated circuits referred to in the art as computers, but broadly refers to microprocessors, microcontrollers, microcomputers, programmable logic controllers, application specific integrated circuits, and other programmable circuits, and these terms are used interchangeably herein.
As will be appreciated by one skilled in the art and based on the foregoing specification, the above-described embodiments of the invention may be implemented using computer programming or engineering techniques including computer software, firmware, hardware or any combination or subset thereof, wherein the technical effect is to calibrate a track circuit. Any such resulting program, having computer-readable code means, may be embodied or provided within one or more computer-readable media, thereby making a computer program product, i.e., an article of manufacture, according to the discussed embodiments of the invention. The computer readable media may be, for example, but is not limited to, a fixed (hard) drive, diskette, optical disk, magnetic tape, semiconductor memory such as read-only memory (ROM), and/or any transmitting/receiving medium such as the Internet or other communication network or link. The article of manufacture containing the computer code may be made and/or used by executing the code directly from one medium, by copying the code from one medium to another medium, or by transmitting the code over a network.
As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
Exemplary embodiments of system and method for automatic calibrating a railroad track circuit are described above in detail. The system and method illustrated are not limited to the specific embodiments described herein, but rather, components of the system may be utilized independently and separately from other components described herein. Further, steps described in the method may be utilized independently and separately from other steps described herein.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
