Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
  • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
  • B60T13/66—Electrical control in fluid-pressure brake systems
  • B60T13/665—Electrical control in fluid-pressure brake systems the systems being specially adapted for transferring two or more command signals, e.g. railway systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
  • B60T17/18—Safety devices; Monitoring
  • B60T17/22—Devices for monitoring or checking brake systems; Signal devices
  • B60T17/228—Devices for monitoring or checking brake systems; Signal devices for railway vehicles

Definitions

• the invention generally relates to a freight train of the type whose brake equipment allows a graduated release and application of the brakes. More particularly, the invention pertains to a novel system and method by which an apparatus, connected to the brake pipe at the end of the freight train, can be used to assist the brake control system in the lead locomotive in applying the brakes of the train.
• a pneumatic trainline known as the "brake pipe” is the means by which service and emergency brake commands are conveyed from the conventional brake control system in the locomotive to each of the railcars in the train.
• the brake pipe 4 is essentially one long continuous tube that runs from the lead locomotive 2 to the last railcar 3 in the train 1.
• the brake pipe 4 is actually composed of a series of interconnected pipes 4a, with one pipe 4a secured to the underside of each railcar.
• the brake pipe 4 is formed by connecting each pipe 4a via a coupler to another such pipe length on an adjacent railcar.
• each of the interconnected pipes 4a that comprise the brake pipe 4 share a common, known diameter.
• the length of the train will also always be a known value.
• the volume of the brake pipe 4 on the train can thus be easily determined to a high degree of accuracy.
• the pneumatic brake equipment on each railcar 3 typically includes two storage reservoirs 9 & 10, one or more brake cylinders 11 and at least one pneumatic brake control valve 12 such as an ADB, ABDX or ABD type valve made by the Westinghouse Air Brake Company (WABCO) .
• WABCO Westinghouse Air Brake Company
• the brake control valve 12 charges the two reservoirs 9 and 10 with the pressurized air it receives from the brake pipe 4. It is the pressure level within the brake pipe 4 that determines whether the brake control valve 12 will indeed charge these reservoirs or deliver pressurized air previously stored in one or both of these reservoirs to the brake cylinders 11.
• the brake cylinders 11 convert the pressurized air that they receive from the brake control valve 12 to mechanical force. From the brake cylinders this force is transmitted by mechanical linkage to the brake shoes.
• the magnitude of the braking force applied to the wheels and/or disc brakes of the railcar is directly proportional to the pressure built up in the brake cylinders. Forced against the wheels and/or disc brakes, the brake shoes are used to slow and/or stop the rotation of the wheels. It is thus the pressure level in the brake pipe 4 that determines whether and to what extent the railcar brakes will be applied.
• the locomotive 2 has its own pneumatic trainlines including a main reservoir equalizing (MRE) pipe, an independent application and release (IAR) pipe, and an actuating pipe.
• MRE main reservoir equalizing
• IAR independent application and release
• actuating pipe Within a locomotive consist (i.e., two or more locomotives connected together), the MRE, actuating and IAR pipes of each locomotive connect to the MRE, actuating and I7AR pipes of the adjacent locomotives.
• the MRE pipe is used to equalize the pressure between the main reservoirs of each locomotive in a consist. Air stored in the main reservoir of a locomotive is used to charge the brake pipe to a normal operating pressure of approximately 90 psi when the brakes are released. It is the pressure within the IAR pipe that controls the delivery of pressurized air to, and thus the operation of, the brakes of the locomotive (s) in the train.
• a conventional brake control system is the 26-L Locomotive Air Brake Control System manufactured by WABCO.
• the 26-L System has two brake handles referred to as the automatic and independent brake handles 21 and 22.
• a train operator in the locomotive can control how the brakes on the locomotive (s) and railcars operate. More specifically, by moving these handles into the proper position, the operator can control how much pressure will be developed in the IAR and brake pipes, as well as in the other pneumatic trainlines of the freight train.
• the pressure level in the brake pipe 4 is what determines how the pneumatic brake equipment on each railcar will operate.
• the operation of the 26-L System is now described, specifically as to how movement of the brake handles 21 and 22 affects the pressure in the brake pipe 4.
• the brake handles are discussed only for purpose of explaining to the reader how the pressure level in the brake pipe 4 can be controlled. It is to be understood that such control may be had by using either brake handles, as in the 26-L System, or other means, as may be used in Europe.
• the train operator can direct the brake control system only to apply or release the brakes on the locomotive (s) .
• the operator can direct the brake control system to apply or release the brakes on both the locomotive (s) and railcars in the train.
• the automatic brake handle 21 can be moved from and in between a release position at one extreme (in which brake pipe pressure is maximum and the brakes are completely released) to an emergency position at another extreme (in which brake pipe pressure is zero and the brakes are fully applied) .
• the positions for the automatic brake handle 21 include release, minimum service, full service, suppression, continuous service, and emergency. Between the minimum and full service positions lies the service zone wherein each incremental movement of the automatic brake handle toward the full service position causes an incremental reduction in brake pipe pressure. The exact amount by which the brake pipe pressure is reduced depends on how far towards the full service position the brake handle 21 is moved. It is this reduction in pressure that signals the brake control valve (s) 12 on each railcar to supply pressurized air from one or both reservoirs 9/10 to the brake cylinders 11 so as to apply the railcar brakes. The amount of pressure built up in the brake cylinders, and thus the magnitude of the braking force applied to the wheels, is proportional to the amount by which the brake pipe pressure has been reduced.
• the way in which the brakes operate depends on whether the brake equipment has been designed to allow a graduated release of the brakes.
• Freight trains in the United States typically use brake equipment that permits only a direct release of the brakes.
• Freight trains in Europe however, feature brake equipment that allows a graduated release of the brakes.
• the brake control system in the locomotive 2 does not command an increase in the pressure within the brake pipe 4 until the automatic brake handle 21 is placed in the release position.
• the brake control system and the railcar brake control valves 12 respond by completely venting the brake cylinders thereby fully releasing the train brakes.
• a preset level e.g. 2 psi
• the brake control system commands an increase in the pressure in the brake pipe 4 incrementally.
• the level to which the brake pipe pressure rises is dependent on the extent to which the automatic brake handle 21 is moved toward the release position.
• those designed for graduated brake release react to this incremental rise in brake pipe pressure by reducing proportionately the pressure in the brake cylinders and thereby the force with which the train brakes are applied.
• Freight trains are often equipped with any one of several known end-of-train (EOT) radio telemetry systems. As shown in Figure 1, these systems typically include a locomotive control unit (LCU) 51 located in the locomotive 2 and an EOT device 55 mounted to the last railcar. The EOT device 55 is coupled to the brake pipe 4 on the last railcar 3 by means of a hose and a glad hand.
• LCU locomotive control unit
• EOT device 55 is coupled to the brake pipe 4 on the last railcar 3 by means of a hose and a glad hand.
• the EOT device 55 transmits by radio signals to the LCU 51 data pertaining to the pressure in the brake pipe and the motion of the last railcar 3.
• the EOT device includes a pressure transducer to monitor brake pipe pressure, a motion sensor to sense movement of the railcar, a microprocessor unit to control the overall operation of these components, and a transmitter that the microprocessor unit uses to transmit this last railcar data.
• the LCU 51 includes a primary display, a receiver to receive transmissions from the EOT device, and a microprocessor unit. Controlled by the microprocessor unit, the primary display of the LCU 51 is used to convey the last railcar data to the train operator.
• the emergency brake application starts at the lead locomotive 2 and progresses along the brake pipe 4 to the last railcar. Especially for long freight trains, reducing the pressure in the brake pipe 4 from the lead locomotive 2 can be quite time consuming. Moreover, if one of the angle cocks 5 is left closed or the brake pipe 4 is otherwise restricted, the brake equipment beyond the restriction may not receive the emergency brake command needed to apply the brakes in an emergency. For this reason, the railroad industry developed two-way EOT radio telemetry systems.
• the LCU and EOT device still perform all of the functions attributed to their counterparts in the one-way EOT system.
• the EOT device 55 is thus still used to transmit the aforementioned radio signals by which last railcar brake pipe pressure and motion data is conveyed to the LCU 51.
• the two-way EOT and LCU devices are each equipped with a transceiver (i.e., combination transmitter and receiver) as compared to the single transmitter and receiver for the one-way EOT and LCU devices, respectively.
• the two-way EOT device 55 also has a pneumatic valve that is controlled by its microprocessor unit, and the LCU 51 also includes an emergency toggle switch.
• the train operator can cause the LCU 51 to transmit an emergency brake radio signal to the EOT device 55.
• the EOT device 55 responds to this emergency signal by commanding its pneumatic valve to reduce the pressure in the brake pipe 4 at an emergency rate.
• the two-way EOT system allows an even faster application of the railcar brakes in an emergency.
• the LCU 51 has a primary display panel which features a dedicated display for each of several types of last railcar data.
• the last railcar data displayed includes brake pipe pressure, low battery condition, whether the railcar is stopped or in motion, and whether an emergency has been enabled or disabled.
• the LCU 51 also has a supplemental message display by which it visually conveys additional information such as, for example, data related to arming of the EOT system and whether or not the EOT device 55 and LCU 51 are communicating properly.
• the brake equipment on a freight train is configured so that an emergency brake application is initiated at a rate faster than a service brake application.
• the emergency reduction in pressure propagates along the brake pipe 4, aided by each successive brake control valve, at a speed of approximately 900 feet/sec. Consequently, for a one mile long freight train, the emergency brake command, if initiated from the head of the train only, would take approximately 10 to 15 seconds to propagate from the lead locomotive 2 to the end of the train.
• a service brake application can take a considerably longer time to reach the last railcar, well over a minute on those freight trains equipped with the older, slower reacting brake control valves. For this reason, the railroad industry developed another type of two-way EOT radio telemetry system, one that permits service brake applications to be implemented at both ends of a freight train.
• the TRAINLINI ⁇ ES EOT system manufactured by WABCO.
• the TRAINLINl ES system has a Service Interface Unit (SIU) 52 that connects between the serial port of the ES LCU 51 and the brake pipe 4 on the locomotive, as shown in Figure 1.
• the SIU 52 provides the ES LCU 51 with the current brake pipe pressure. This allows the ES LCU 51 to initiate automatically a service brake application at the last railcar simultaneously with the service reduction in brake pipe pressure initiated from the lead locomotive 2.
• the ES LCU 51 in the locomotive 2 automatically transmits a service brake radio signal to the ES EOT device 55 when it detects a service reduction in brake pipe pressure via the SIU 52.
• the two-way ES EOT device 55 responds to this service brake signal by commanding its valve to reduce the brake pipe pressure from the last railcar at approximately the same service rate as that ordered by the brake control system in the lead locomotive 2.
• a service application of the brakes can thus be made much faster on a freight train equipped with a TRAINLINFL® ES or similar type EOT system.
• the ES LCU 51 can also automatically transmit an emergency brake signal when an emergency reduction in brake pipe pressure has been initiated by the brake control system in the locomotive 2.
• the emergency toggle switch on the ES LCU 51 can also be used to transmit this emergency brake signal .
• Many European freight trains use a brake control system that employs a different scheme of initiating a service application of the brakes on the train.
• the brake control system in the lead locomotive 2 is designed to emit a quick service pulse (QSP) which the brake pipe 4 conveys sequentially to each railcar 3 in the train.
• QSP quick service pulse
• the QSP is manifested as a brief drop in pressure, one whose characteristic is distinct from any service brake command and easily recognized by the pneumatic brake equipment on each railcar.
• the QSP propagates along the brake pipe 4 far more rapidly than does a service brake command. It is used to inform each railcar that the brake control system will soon issue a service brake command.
• each brake control valve 12 is designed to reduce the brake pipe pressure locally by a set minimal amount. Conveyed along the brake pipe 4 just prior to the service brake command, the QSP is a means of reducing the amount of time it takes for the brake equipment to implement a service brake application on the train. No matter what type of freight train one considers, a primary goal is to apply the brakes on every vehicle in the shortest possible time. European freight trains that employ the QSP scheme to initiate a service brake application, however, are usually limited in length because even the QSP takes time to propagate the length of the train.
• the overall time it takes to implement a service brake application on QSP-schemed European freight trains can be reduced.
• the LCU in the locomotive 2 would automatically transmit a service brake radio signal to the EOT device when it detects a service reduction in brake pipe pressure via the SIU.
• the EOT device would then respond to the service brake signal by commanding its valve to reduce the pressure in the brake pipe 4 on the last railcar at nearly the same service rate as that ordered by the brake control system in the lead locomotive 2.
• Such a two-way EOT system can be easily implemented on European freight trains, and would make possible the use of longer QSP-schemed trains.
• the radio link between the LCU and the EOT device may not be completely infallible, especially when the train passes under bridges, through tunnels or as it winds it way through mountainous regions.
• the terrain in which a freight train operates may have a topography with natural, or man-made, obstructions which could block or, at the very least, interfere with the transmission and reception of the radio signals.
• the EOT device could be configured to detect the QSP using its pressure transducer. Once the QSP is detected, the EOT device by its microprocessor unit could then command its valve to reduce locally the pressure in the brake pipe 4 by the aforementioned set amount. Alternatively, its microprocessor unit could be programmed to respond to the QSP by opening the valve for a set period of time (e.g., 15-20 seconds) to make a more substantial reduction in brake pipe pressure.
• the pressure in the brake pipe at the rear end of the train would increase or decrease depending on the magnitude of the service brake command issued by the brake control system in the locomotive. Consequently, should it be unable to receive and react to the service brake radio signal, the EOT device would always be able to detect and react to the QSP. For whatever reason the radio link fails, this technique would permit the EOT device to contribute, albeit minimally, to the overall reduction in brake pipe pressure required by the brake control system to implement a service application of the brakes.
• the primary problem with this technique is that the QSP conveys no information other than the knowledge that a service brake command will soon be issued. Consequently, the QSP does not inform the EOT device of the magnitude of the upcoming service brake application.
• the EOT device can only get the information regarding the magnitude of the brake application from the service brake radio signal.
• the aforementioned technique does allow the EOT device to act upon the QSP whether or not the service brake radio signal is received. Unfortunately, it also leaves the EOT device incapable of implementing locally the correct level of service braking whenever the EOT radio link fails.
• Another objective is to provide a system and method of assisting the brake control system in the locomotive in implementing a service application of the brakes not by relying on an EOT radio link to convey and act upon radio brake signals but by monitoring the brake pipe at the end of the train and affecting the pressure thereat based on the change in the flow of air in the brake pipe initiated by the brake control system.
• Yet another objective is to provide a system and method of assisting the brake control system in the locomotive in implementing a service application of the brakes, and, in so doing, keep draft forces at safe levels and prevent excessive wear of brake equipment, as compared to prior art techniques.
• the invention provides an apparatus for, and a method of, assisting a brake control system in a locomotive in implementing a service application of the brakes on rail vehicles of a freight train.
• the train carries a brake pipe along which the brake control system conveys a quick service pulse (QSP) as a precursor to conveying a service brake command to all rail vehicles in the train.
• QSP quick service pulse
• the brake control system is capable of deriving a service brake command by which it orders the brakes of the rail vehicles to implement a service application of the desired magnitude.
• the apparatus includes a pressure transducer, a pneumatic valve, a means for measuring flow rate, and a microprocessor unit.
• the pressure transducer is used to measure the pressure within the rear end of the brake pipe.
• the valve When opened, the valve is used to exhaust air from the rear end of the brake pipe.
• the means for measuring flow rate is used to measure the rate at which air exhausts from the brake pipe when the valve is open.
• the microprocessor unit is used to control the opening and closing of the valve in response to readings taken from the transducer or the means for measuring flow rate or both. In response to a reading from the transducer indicative of the QSP, the microprocessor unit will open the valve thereby allowing air to exhaust from the rear end of the brake pipe. Using the values of flow rate provided by the means for measuring, the microprocessor unit will calculate regularly the actual quantity of air that has exhausted thus far through the valve.
• the microprocessor unit will compare the actual quantity of air with an expected quantity of air. Based on the results of the comparison, the microprocessor unit will manipulate the valve, after a preset time, as follows. If the actual quantity of air is nearly equal to the expected quantity, air continues to exhaust from the rear end of the brake pipe until the actual quantity starts to exceed the expected quantity according to a flow rate curve currently in effect. If the actual quantity of air fails to accrue to within a prefigured amount of the expected quantity, air exhausts until the actual quantity of air equals or exceeds the expected quantity according to an elevated flow rate curve.
• the apparatus aids the brake control system in the locomotive in making a service application of the brakes on the rail vehicles with the desired magnitude.
• a flow rate curve is formulated according to which air within the rear end of the brake pipe will be expected to exhaust when the QSP is detected there.
• the rear end of the brake pipe is monitored for the QSP to be issued by the brake control system. As soon as the QSP is detected, air is allowed to exhaust from the rear end of the brake pipe.
• the flow rate the rate at which air is being exhausted from the rear end of the brake pipe— is monitored continuously. Using the values of flow rate previously discerned, the actual quantity of air that has been exhausted from the rear end of the brake pipe is calculated regularly. As it accrues, the actual quantity of air is compared with an expected quantity of air as time passes.
• the expected quantity is the total amount of air that is expected to exhaust from the rear end of the brake pipe at any given time if both ends of the brake pipe were to exhaust air according to the flow rate curve currently in effect. If, after a preset time, the actual quantity of air fails to accrue to within a prefigured amount of the expected quantity, the amount or air oeing exnauste ⁇ rro the rear end ot the brale pipe is increased until the actual quantity of air equals or exceeds the expected quantity according to an elevated flow rate curve. If the actual quantity of air is nearly equal to the expected quantity, air will continue to exhaust from the brake pipe until the actual quantity of air starts to exceed the expected quantity according to the flow rate curve currently in effect.
• a suitable apparatus can aid the brake control system in the locomotive in making a service application of the brakes.
• Figure 1 illustrates a freight train equipped with a conventional brake control system and a two-way end-of-train (EOT) radio telemetry system.
• Figure 2 illustrates the brake pipe of a freight railcar and the pneumatic brake equipment to which it connects.
• Figure 3 illustrates an EOT apparatus, according to the invention, that employs a flow meter to measure the rate at which air exhausts from the rear end of the brake pipe.
• Figure 4 illustrates an EOT apparatus, according to the invention, that employs a transducer and pressure versus fl ow ra te table to measure the rate at which air exhausts from the rear end of the brake pipe.
• Figure 5 illustrates a flow rate profile for the invention as it assists the brake control system in implementing a service application whose magnitude is midway between that required for a minimum and a full application of the brakes.
• Figure 6 illustrates a flow rate profile for the invention as it assists the brake control system in implementing a service application whose magnitude is below that required for a mid-level application.
• Figure 7 illustrates a flow rate profile for the invention as it assists the brake control system in implementing a service application whose magnitude is above that required for a mid-level application.
• Figures 8A and 8B show a block diagram of the steps of the method according to the invention.
• FIG 3 illustrates a specially configured end-of- train (EOT) type apparatus, generally designated 60.
• the EOT apparatus 60 includes a pressure transducer 61, a pneumatic valve 62, a microprocessor unit 63 and a flow meter 6 .
• Figure 4 illustrates an alternative embodiment of the EOT apparatus in which the flow meter is absent.
• the function of the EOT apparatus 60 in either embodiment, is to ascertain pneumatically the magnitude of the service brake application sought by the brake control system in the lead locomotive 2. Its primary goal is to assist the brake control system in implementing whatever magnitude of service brake application it desires for the train.
• the pressure transducer 61 is used to detect the quick service pulse (QSP) and otherwise monitor the pressure within brake pipe 4 at the rear of the train. It converts the pressure to which it is exposed into an electrical signal whose attributes correspond to the characteristics of the pressure existing within brake pipe 4 at the time of the conversion.
• QSP quick service pulse
• the pneumatic valve 62 allows the pressure within brake pipe 4 at the rear of the train to exhaust to atmosphere. Even as the pressure changes within the brake pipe, the microprocessor unit 63 can maintain the rate at which air exhausts to atmosphere by varying the size of the orifice of the valve 62 through which the air escapes. With the pneumatic valve 62 open, the flow meter 64 can be used to measure directly the rate at which air exhausts from the brake pipe 4 at the rear of the train.
• the microprocessor unit 63 is accompanied by the appropriate volatile and non-volatile memories to store data and programming code.
• Stored in this memory may be a pressure versus flow rate table whose values can be derived by empirical measurement.
• Flow rate again refers to the rate at which air will exhaust from brake pipe 4 when the valve 62 of the EOT apparatus 60 is open.
• Flow rate again refers to the rate at which air will exhaust from brake pipe 4 when the valve 62 of the EOT apparatus 60 is open.
• a distinct flow rate can be measured for, and will correspond to, each value of pressure within brake pipe 4.
• the microprocessor unit 63 can match each pressure reading it takes to its corresponding flow rate in the table. It is in this manner that the microprocessor unit 63 can keep track of the flow rate nearly continuously at the rear end of brake pipe 4.
• the microprocessor unit 63 can be kept apprised of the flow rate by taking readings directly from the flow meter 64. No matter how the flow rate values are obtained, by integrating them over time, the microprocessor unit 63 can calculate a reasonable estimate of how much air has exhausted to atmosphere while the pneumatic valve 62 has been held open.
• the brake control system in the lead locomotive 2 first issues the quick service pulse (QSP) . Shortly thereafter, it issues the service brake command along the brake pipe 4 to all of the railcars in the train. It is with the QSP that the brake control system primes the brake pipe 4 for the upcoming service brake command, i.e., it compels each of the brake control valves 12 to reduce the pressure locally by a set minimal amount. It is with the service brake command, however, that the brake control system actually orders the brake equipment on each railcar 3 to apply (i.e., to make a service application of) the brakes.
• QSP quick service pulse
• the magnitude of the service brake application is also conveyed by the service brake command and is manifested as the extent to which the brake control system reduces the pressure in the brake pipe 4 from the front of the train. It represents the force with which the brakes should apply on each railcar.
• the EOT apparatus 60 of this invention is intended to assist the brake control system in the lead locomotive 2 in implementing a service application of the brakes on the train. Generally, in response to the QSP it receives from the brake control system, the EOT apparatus 60 shall immediately begin to reduce the pressure within brake pipe 4 at the rear of the train. As explained infra, the EOT apparatus 60 shall also determine whether air exhausts from the brake pipe according to a predetermined flow rate curve.
• the brake control system in the locomotive 2 issues the service brake command. It is the goal of the EOT apparatus 60 to assist the brake control system at the other end of the train in generating the desired service brake command (i.e., the desired reduction in pressure) throughout brake pipe 4.
• the EOT apparatus 60 and the brake control system together can more quickly reduce the pressure within brake pipe 4 to the desired level, throughout the length of the train, than could the brake control system by itself from the front of the train. This allows the brake control valves 12 on the railcars 3 to carry out more quickly the service brake command derived by the brake control system.
• the EOT apparatus 60 will, of course, exhaust air from the end of brake pipe 4 located opposite the brake control system in locomotive 2. The resulting reduction in pressure will thus propagate inwardly from the ends of brake pipe 4 towards the middle of the train.
• the predetermined flow rate curve can be formulated to signify a brake command of any magnitude. It represents the variation that is expected to occur in the rate of flow when air is allowed to exhaust from the rear end of the brake pipe in response to the QSP. If both EOT apparatus 60 and the brake control system were exhausting air according to the same flow rate curve, the total amount of air that would be expected to exhaust from valve 62 would be, at any given time, the same as that exhausted from the front end of brake pipe 4.
• the predetermined flow rate curve will preferably manifest a mid- level service brake command. Notwithstanding the reduction emanating from the front, this fixed, expected quantity of air is herein referred to as Q EXP . It is preferably chosen to be the same amount of air that the brake control system must exhaust at the front of the train to convey a mid-level service brake command along the brake pipe. By selecting such a mid range value for Q E /p, the EOT apparatus 60 will be better able to assist the brake control system in the locomotive 2 in implementing both minimum and full service brake applications. Whether the EOT apparatus 60 will actually dump Q E >- F depends, however, on the magnitude of the brake command issued by the brake control system. The invention assists the brake control system in the lead locomotive 2 in implementing a service brake application of any magnitude.
• the EOT apparatus 60 shall first be described as to how it assists the brake control system in implementing a service application whose magnitude is midway between that required for a minimum and a full application of the brakes. It shall then be described as to how it assists the brake control system in implementing a service application whose magnitude is below that required for a mid-level application. Lastly, the EOT apparatus 60 shall be described as to how it assists the brake control system in implementing a service application whose magnitude is above that required for a mid-level application.
• the EOT apparatus 60 is now described as to how it assists the brake control system in implementing a mid-level service application of the brakes.
• the brake control system in the lead locomotive 2 issues the QSP along the brake pipe 4 of the train 1.
• the brake control valves 12 on each railcar 3 react to the QSP in sequence by priming the brake pipe for the upcoming mid-level service brake command.
• the EOT apparatus 60 uses its pressure transducer 61 and microprocessor unit 63 to detect the QSP as soon as it reaches the rear end of brake pipe 4. Specifically, the microprocessor unit 63 receives from the pressure transducer 61 a signal whose electrical characteristics unmistakably indicate the presence of the QSP. The microprocessor unit 63 responds to the QSP by opening the pneumatic valve 62, thereby allowing air to exhaust from the rear end of the brake pipe to atmosphere.
• the brake control system in the locomotive 2 issues the mid-level service brake command according to prior art practice. By this particular command, the brake control system seeks to implement a reduction in brake pipe pressure of a magnitude midway between a minimum and a full service reduction.
• the brake control system will exhaust air from the front end of brake pipe 4 and, in doing so, decrease the brake pipe pressure at a preset rate.
• the mid-level reduction lasts approximately 15 seconds at a preset rate of about 1 psi/second, for a total of approximately 15 psi .
• the brake control system With this particular service brake command, the brake control system thus seeks to exhaust from the front end of brake pipe 4 the same amount of air that the EOT apparatus 60 expects to exhaust from the rear end of the brake pipe .
• the microprocessor unit 63 continuously monitors the rate at which air flows from valve 62. As noted above, the microprocessor unit 63 can monitor the actual flow rate either directly using flow meter 64 or indirectly using transducer 61 in conjunction with the pressure versus flow rate table. The EOT apparatus 60 uses the actual flow rate values obtained during such monitoring to determine whether the air is being exhausted according to the predetermined flow rate curve (i.e., curve C P ) shown in Figure 5. No matter how the actual flow rate values are obtained, the microprocessor unit 63 integrates them over time so as to keep itself continuously apprised of the actual amount of air, Q ACTV that has thus far been exhausted from the rear end of brake pipe 4. Preprogrammed with the expected flow rate values that comprise the predetermined flow rate curve, the EOT apparatus 60 is able to determine, by integration of all preceding values on the curve, the amount of air, Q E ⁇ p, that should have exhausted at any given point in time.
• the microprocessor unit 63 will compare Q AC ⁇ with Q EXP as time passes. Given that the brake control system has ordered here a mid-level service brake command, the actual flow rate values observed by microprocessor unit 63 at valve 62 should, if plotted, very nearly trace out the predetermined flow rate curve C P in Figure 5. In other words, the total amount of air, Q ACT , that the EOT apparatus 60 has exhausted from the rear end of brake pipe 4 at any given point in time should equal the amount of air expected from curve C P to be exhausted up to that time, i.e., Q EXP . Assuming this mid-level service brake command and the curve Cp, any difference between Q EXP and Q ACT should be minimal at any given point in time.
• the microprocessor unit 63 will infer the following. First, the brake control system in the lead locomotive 2 was exhausting roughly the same quantity of air from the front end of brake pipe 4 as the EOT apparatus 60 was from the rear. Second, in exhausting that quantity of air (i.e., Q EXP ) / the brake control system must have issued a mid-level magnitude service brake command. Because air has been exhausting from the front and rear ends of brake pipe 4 essentially at the same rate and in the same quantity, the microprocessor unit 63 will eventually close the pneumatic valve 62 as indicated by the flow rate curve C P in Figure 5. The pressure at opposite ends of brake pipe 4 will then have been allowed to drop by a preselected amount, PSET-
• the EOT apparatus 60 is now described as to how it assists the brake control system in implementing a service brake application whose magnitude is below that required for a mid- level application.
• the brake control system in the locomotive issues the QSP along brake pipe 4 sequentially to all railcars 3 in the train 1.
• the brake control valves 12 on each railcar 3 react to the QSP in sequence by priming the brake pipe for the upcoming low magnitude service brake command.
• the EOT apparatus 60 Using its pressure transducer 61 and microprocessor unit 63, the EOT apparatus 60 detects the QSP as soon as it reaches the rear end of brake pipe 4.
• the microprocessor unit 63 responds to the QSP by opening the pneumatic valve 62. Also capable of varying the extent to which valve 62 opens, the microprocessor unit 63 begins to exhaust air from the rear end of brake pipe 4.
• the brake control system in the locomotive 2 issues the low magnitude service brake command according to prior art practice.
• the brake control system seeks to implement a reduction in brake pipe pressure of a magnitude lower than that required for a mid-level service application of the brakes.
• the brake control system will exhaust from the front end of brake pipe 4 a smaller amount of air, Q L ow, than it would for a mid-level brake command.
• the magnitude or value of Q L ow depends, of course, on how slight of a service brake application is being ordered.
• the rate at which the air will be exhausted will be lower, or its duration will be shorter, than that typically required to carry out the mid-level service brake command.
• the brake control system seeks to exhaust less air than the EOT apparatus 60 initially expects it to exhaust.
• the microprocessor unit 63 While the brake control system and EOT apparatus 60 exhaust air from opposite ends of the brake pipe, the microprocessor unit 63 continuously monitors the rate at which air flows from valve 62. The EOT apparatus 60 uses the actual flow rate values obtained during such monitoring to determine whether the air is being exhausted according to the predetermined flow rate curve C P shown in Figure 6. By integrating the actual flow rate values obtained from such monitoring, the microprocessor unit 63 keeps itself continuously apprised of the actual amount of air, Q ACT , that has thus far exhausted from the rear end of brake pipe 4. Microprocessor unit 63 can also compare the actual flow rate values with the expected flow rate values that comprise the predetermined flow rate curve C P .
• the microprocessor unit 63 is able to derive, by integrating all preceding values on curve C P , the total amount of air, Q E ⁇ P , that it expects to have exhausted through valve 62 at any given point in time. Operating according to its programming code, the microprocessor unit 63 will compare Q AC ⁇ with Q EXP on a continual basis. Given that the brake control system has ordered here a low magnitude service brake command, the actual flow rate values initially observed by microprocessor unit 63 at valve 62 will, if plotted, not trace out the predetermined flow rate curve C P shown in Figure 6. Instead, the observed flow rate values will, at least initially, plot out the curve C B ⁇ shown in Figure 6.
• This curve shows that that the rate at which air is exhausting from valve 62 is higher than expected, significantly higher than it would be if the brake control system were implementing a mid- level or higher magnitude service brake command. From these high flow rate values, the microprocessor unit 63 is informed that the brake control system has dumped from the front end of the brake pipe less air than expected for a mid-level service brake command. In other words, the amount of air that has thus far exhausted from valve 62 (i.e., Q A ⁇ ) is greater than the amount expected (i.e., QEXP) from curve C P during this time period.
• the microprocessor unit 63 By continually comparing the actual and expected flow rate values, the microprocessor unit 63 will be able to approximate the magnitude of the serve brake application currently being sought by the brake control system in the locomotive 2.
• the microprocessor unit 63 derives a new flow rate curve, identified as curve C TARGET in Figure 6, based on the magnitude of the difference between the actual and expected flow rate values.
• the new flow rate curve is comprised of a new set of flow rate values that serve as targets for the EOT apparatus 60 to meet. From the new flow rate curve, the EOT apparatus is informed about how much air that it should expect the brake control system to have exhausted at any given time, given the low magnitude service brake command currently in effect.
• the microprocessor unit 63 will adjust the extent to which valve 62 is open so that the actual amount of air vented to atmosphere, i.e., Q A c ⁇ / will closely track that being exhausted from the front end of the brake pipe. With the air now being exhausted from both ends of the brake pipe approximately at the same rate and in the same quantity, the microprocessor unit 63 will eventually close the pneumatic valve 62 as indicated by flow rate curve C TAR GET in Figure 6.
• the EOT apparatus 60 thus derives and uses the new flow rate curve to more closely comport its operation with that of the brake control system in the locomotive .
• the EOT apparatus 60 is now described as to how it assists the brake control system in implementing a service application whose magnitude is above that required for a mid- level application of the brakes.
• the brake control system in the lead locomotive 2 issues the QSP along brake pipe 4 sequentially to all railcars 3 in the train 1.
• the brake control valves 12 on each railcar 3 react to the QSP in sequence by priming the brake pipe for the upcoming high magnitude service brake command .
• the EOT apparatus 60 detects the QSP as soon as it reaches the rear end of brake pipe 4.
• the microprocessor unit 63 then responds to the QSP by opening the pneumatic valve 62 so that air exhausts from the rear end of brake pipe 4 at the preset rate.
• the brake control system in the locomotive 2 issues the high magnitude service brake command according to prior art practice.
• the brake control system seeks to reduce the pressure in the brake pipe by an amount greater than that required for a mid-level service application of the brakes. In doing so, the brake control system will exhaust from the front end of brake pipe 4 a larger amount of air, Q HIGH , than it would for a mid-level brake command.
• the magnitude of Q HIGH depends, of course, on the strength of the service brake application being ordered. Whatever the magnitude of this high level service brake command, its duration will, of course, be more than the 15 seconds typically required to carry out a mid-level service brake command.
• the brake control system seeks to exhaust more air than the EOT apparatus 60 initially expects it to exhaust from the predetermined flow rate curve C P shown in Figure 7. While the brake control system and EOT apparatus 60 exhaust air from opposite ends of the brake pipe, the microprocessor unit 63 continuously monitors the rate at which air flows from valve 62. The actual flow rate values obtained during such monitoring are used to determine whether the air is being exhausted according to the predetermined flow rate curve Cp. By integrating the actual flow rate values obtained during such monitoring, the microprocessor unit 63 keeps itself continuously apprised of the actual amount of air, Q AC ⁇ / that has thus far exhausted from the rear end of brake pipe 4.
• Microprocessor unit 63 compares the actual flow rate values with the expected flow rate values that comprise the predetermined flow rate curve C P . Preprogrammed with these expected flow rate values, the microprocessor unit 63 can derive, by integrating all preceding values on curve C P , the total amount of air, Q EXP , that it expects to have exhausted through valve 62 at any given point in time.
• the microprocessor unit 63 will compare Q AC ⁇ with Q EXP on a continual basis. Given that the brake control system has ordered here a high magnitude service brake command, the actual flow rate values initially observed by microprocessor unit 63 at valve 62 will, if plotted, not trace out the predetermined flow rate curve C P shown in Figure 7. Instead, the observed flow rate values will, at least initially, plot out the curve C B2 shown in Figure 7. This curve shows that that the rate at which air is exhausting from valve 62 is lower than expected, significantly lower than it would be if the brake control system were implementing a mid-level or lower magnitude service brake command.
• the microprocessor unit 63 is informed that the brake control system has dumped from the front end of the brake pipe more air than expected for a mid-level service brake command.
• the amount of air that has thus far exhausted from valve 62 i.e., Q AC T
• the amount expected from curve C P i.e., Q EXP
• the microprocessor unit 63 By continually comparing the actual and expected flow rate values, the microprocessor unit 63 will be able to approximate the magnitude of the serve brake application currently being sought by the brake control system at the front of the train.
• the microprocessor unit 63 derives a new flow rate curve, identified as curve C TA RG E T in Figure 7, based on the magnitude of the difference between the actual and expected flow rate values.
• the new flow rate curve is comprised of a new set of flow rate values that serve as targets for the EOT apparatus 60 to meet. From the new flow rate curve, the EOT apparatus is informed about how much air that it should expect the brake control system to have exhausted at any given time, given the high magnitude service brake command currently in effect.
• the microprocessor unit 63 w ll adjust the extent to which valve 62 is open so that the actual amount of a r vented to atmosphere, i.e., Q ACTA will closely track that being exhausted from the front end of the brake pipe. With the air now being exhausted from both ends of the brake pipe approximately at the same rate and in the same quantity, the microprocessor unit 63 will eventually close the pneumatic valve 62 as indicated by flow rate curve C TARGET in Figure 7.
• the EOT apparatus 60 thus derives and uses the new flow rate curve to more closely comport its operation with that of the brake control system m the lead locomotive 2.
• the flow meter 64 along with the microprocessor unit 63 --to the extent that it aids m measuring flow rate, essentially serve as a means for measuring the rate at which air exhausts from the rear end of the brake pipe.
• the pressure transducer 61, the pressure versus flow ra te table, and, again, the microprocessor unit 63 also basically constitute a means for measuring the rate at which air exhausts from the rear end of the brake pipe. It is intended that various other arrangements of these parts or even different parts that together perform the same function as the cited means are to be encompassed by one or more of the following claims.
• Figures 8A-8B show the essential steps for a method of assisting the brake control system in the lead locomotive 2 in implementing a service application of the brakes on a train.
• This method does not rely on an EOT radio link to convey and act upon radio brake signals to accomplish the objective, even though it can be used in conjunction with an ES EOT radio telemetry system.
• an initial flow rate curve is formulated.
• This predetermined flow rate curve represents the variations that are expected to occur in the rate of flow when air is allowed to exhaust from the rear end of the brake pipe in response to the QSP.
• this initial flow rate curve also depends on the operating pressure inherent to the brake equipment and piping of the train on which the method is to be used.
• the rear end of the brake pipe is monitored for the QSP to be issued by the brake control system.
• air is allowed to exhaust from the rear end of the brake pipe.
• the flow rate the rate at which air is being exhausted from the rear end of the brake pipe— is monitored continuously.
• the actual quantity of air that has been exhausted from the rear end of the brake pipe is calculated regularly. As it accrues, the actual quantity of air is compared with an expected quantity of air as time passes.
• the expected quantity is the total amount of air that is expected to have exhausted from the rear end of the brake pipe at any given time if both ends of the brake pipe were exhausting air according to the flow rate curve currently in effect.
• the amount of air being exhausted from the rear end of the brake pipe is increased according to an elevated flow rate curve until the actual quantity of air equals or exceeds the expected quantity. If the actual quantity of air is nearly equal to the expected quantity, air will continue to exhaust from the brake pipe according to the flow rate curve currently in effect until the actual quantity of air starts to exceed the expected quantity. If the actual quantity of air exceeds the expected quantity, the flow of air from the rear end of the brake pipe is continuously reduced according to a lowered flow rate curve until the actual quantity of air equals the expected quantity. The exhaustion of air will eventually cease according to the flow rate curve currently in effect.
• an EOT apparatus can assist the brake control system in the locomotive in dropping the pressure throughout the brake pipe to the target level dictated by the service brake command.
• the invention may be carried out using an existing EOT device, such as the ES EOT device 55 described in the background section of this document. This would, however, require extensive modification to the ES EOT device.
• the pressure versus flow rate table would have to be stored in the memory of the microprocessor unit.
• the ES EOT device would also need its programming code modified to accommodate the algorithms embodied in the foregoing method steps .
• the microprocessor unit 63 would also need to be interfaced with the flow meter to accomplish the method, and realize the system, described in the foregoing paragraphs.

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• Engineering & Computer Science (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Braking Systems And Boosters (AREA)

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• 1999
  • 1999-08-06 WO PCT/US1999/017896 patent/WO2001010695A1/en not_active Application Discontinuation
  • 1999-08-06 EP EP99940939A patent/EP1226057A4/de not_active Withdrawn

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