Abstract:
Methods and systems for control and use in connection with an electronically controlled pneumatic (ECP)-equipped train after transmission of a brake pipe emergency dump command message by a helper locomotive associated with the train. These methods and systems are implemented in an effort to improve braking safety and reduce brake system recovery time of a train.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a system and method for addressing a pneumatic emergency initiated in a helper locomotive and, more particularly, to a system and method of improving braking safety and reducing brake system recovery time in an electronically controlled pneumatic (ECP)-equipped train after transmission of a brake pipe emergency dump command message by the helper locomotive associated with the train. 
     2. Description of Related Art 
     The air brake system on a train includes a brake pipe which extends the length of the train. The pressure is maintained in the brake pipe by the lead locomotive except when the engineer in the lead locomotive applies the brakes by releasing air pressure. The drop in air pressure propagates down the brake pipe causing brakes to be applied by the locomotives and all the cars in the train. With the advent of two-way end-of-train (EOT) units, an emergency braking event can be initiated by the engineer by causing air pressure to be vented simultaneously at the front and back of the train. The EOT unit is mounted on a coupler of the last car of the train, and specific coupler mounts have been designed to allow a helper locomotive to couple to the last train without damaging the EOT unit. 
     A helper locomotive may provide additional braking or motive power to the train. For example, in a train a mile long, a consist having three locomotives may provide sufficient power for a run along average grade terrain. However, a run over an above-average grade may require additional power in the form of a helper locomotive being attached to the end of the train just before traversing the increased grade. Once the train has cleared the increased grade, the helper locomotive is disconnected and may return to its point of origin. Current brake pipes of helper locomotives are connected to the train in one of two manners: a direct physical connection or a virtual connection. With a physical connection, the brake pipe hose of a helper locomotive has a connection to the train. This makes the brakes of the helper locomotive respond like any other car in the train, thus giving control of the brakes to the engineer in the lead locomotive. Coupling and uncoupling of the brake hose of the helper locomotive to the train is accomplished manually. Both operations expose railroad personnel to risk of serious injury. With a virtual connection, the brake pipe hose of the helper locomotive is connected to special radio-based helper equipment and the brake pipe pressure is communicated between the train and the helper locomotive via the existing radio system. Therefore, a safer alternative in adding braking functionality to the helper locomotive that uses a virtual connection is found in electronically controlled pneumatic (ECP) trains. 
     An ECP-equipped train relies on electronic signals, rather than changes in brake pipe air pressure, to activate brake valves on individual freight cars. Because signal propagation from the first to last car is instantaneous, the rate of brake cylinder pressure buildup can be increased. With conventional pneumatic brakes, brake cylinder pressure buildup time is carefully retarded to prevent the last cars in a train, where the brakes have not yet applied, from running into the first cars with fully developed brake cylinder pressure. With ECP, cylinder pressure buildup is about 6 to 7 psi/second for both emergency and service brake applications. The brakes can be applied, partially released, and then reapplied as often as necessary, within the ability of the locomotive compressors to replenish reservoirs on the cars of a long train. 
     In the context of a helper locomotive with a virtual brake pipe connection, ECP-equipped trains do not require that a physical brake pipe connection be made between the train and the helper locomotive. Specifically, a system is provided for forming a virtual brake pipe connection between the head-end-unit (HEU) of the helper locomotive and the EOT unit of the train. Thus, the EOT unit reads ECP braking commands from the ECP trainline and translates them into radio messages, which are sent to the helper locomotive. The system then sets the braking on the helper locomotive to match that of the ECP braking application on the train. A commercial system that implements the aforementioned functionality is known as HelperLink™ by Wabtec Railway Electronics. 
     As is known in the art, the aforementioned system may also initiate braking in the context of issuing an emergency brake application to the associated train based on a pneumatic emergency experienced on the helper locomotive or if the engineer of the helper locomotive is aware of a situation affecting the train that would require an emergency brake application. In such an instance, the emergency brake application involves the transmission of a brake pipe emergency dump command from the helper locomotive to the EOT unit. Upon receipt of the brake pipe emergency dump command, the EOT unit would open the brake pipe dump valve, which results in immediate discharge of the brake pipe of the train, and an immediate application of the brakes on all cars to an emergency level. This sudden and non-graduated removal of air from the brake pipe increases in-train forces and results in depletion of all air, which requires a lengthy recharging and testing of the entire brake system before the train may continue its travel. 
     Thus, there is a need for a system and method that overcomes or addresses some or all of the limitations of the existing ECP train systems and arrangements. 
     SUMMARY OF THE INVENTION 
     Generally, the present invention provides a system and method for addressing a pneumatic emergency in a helper train that address some or all of the deficiencies and drawbacks associated with existing electronically controlled pneumatic (ECP)-equipped trains and components. 
     Accordingly, in one preferred and non-limiting embodiment, provided is a method for improving braking safety and reducing brake system recovery time in an electronically controlled pneumatic (ECP)-equipped train after transmission of a brake pipe emergency dump command message by a helper locomotive associated with the train having multiple cars. This method includes: (a) receiving the brake pipe emergency dump command message at an end-of-train (EOT) unit associated with the train; (b) transmitting an ECP emergency brake request message from the EOT unit to at least one car in the train and a head-end-unit (HEU) of the train; (c) waiting a predetermined period of time after transmitting the ECP emergency brake request message, for receipt of an ECP head-of-train (HOT) brake command message transmitted by the HEU (e.g., indicating that the ECP emergency brake command has been received by the HEU); and (d) opening a brake pipe dump valve if the ECP HOT brake command message has not been issued to the at least one car in the train within the predetermined period of time. The ECP emergency brake request message is a message that requests that the train be stopped and/or a message that identifies that the helper locomotive has gone into a pneumatic emergency. 
     The brake pipe dump valve may be in fluid communication with a brake pipe of the train. The helper locomotive may be a pusher locomotive coupled to an end of the train without a physical connection to the brake pipe of the train. The predetermined period of time may be from about 1 to about 10 seconds, and preferably from about 3 to about 5 seconds. The ECP HOT brake command message may be: an emergency train brake command (TBC), or as is known in the art, a TBC=120% command; or some lesser or reduced brake command. Receipt of the brake pipe emergency dump command message may occur on an EOT radio network, and the EOT transmission of the ECP emergency brake request to the cars and to the ECP HEU, and receipt of the ECP HOT brake command message may occur on an ECP messaging network. 
     In a further preferred and non-limiting embodiment, provided is directed to an EOT unit for use in improving braking safety and reducing brake system recovery time in an ECP-equipped train after transmission of a brake pipe emergency dump command message by a helper locomotive associated with the train. This unit includes: a brake pipe dump valve; an EOT radio receiver for receiving the brake pipe emergency dump command message; an ECP transmitter for transmitting an ECP emergency brake request message; an ECP trainline receiver for receiving an ECP HOT brake command message; and a processor for determining if the ECP HOT brake command message has been received within a predetermined period of time after transmitting the ECP emergency brake request message, where, if a determination is made that the ECP HOT brake command message has not been received within the predetermined period of time, causing the brake pipe dump valve to be opened. 
     In a further preferred and non-limiting embodiment, provided is a system for improving braking safety and reducing brake system recovery time in an ECP-equipped train after transmission of a brake pipe emergency dump command message by a helper locomotive associated with the train. The system includes: an EOT radio network; a helper locomotive equipped with a virtual brake pipe connection, wherein the helper locomotive is configured to transmit the brake pipe emergency dump command message on the EOT radio network; an EOT unit situated on the train, wherein the EOT unit is configured to receive the brake pipe emergency dump command message from the EOT radio network, and in response thereto, transmit an ECP emergency braking request message on an ECP messaging network, wherein the EOT unit includes a brake pipe dump valve, and wherein at least one car in the train is configured to respond to an ECP emergency braking request message from the ECP messaging network from the EOT; and an HEU situated on the train, wherein the HEU of the train is configured to transmit an ECP HOT brake command message on the ECP messaging network, and wherein the EOT unit is further configured to open the brake pipe dump valve if the ECP HOT brake command message has not been received within a predetermined period of time after transmitting the ECP emergency brake request message. 
     By utilizing an ECP EOT emergency brake command request to activate the brakes on the cars corresponding to an emergency braking command (e.g., TBC=120% command) or corresponding to a lesser or reduced TBC brake command, as opposed to a traditional EOT brake pipe emergency dump command at the EOT unit, the benefits associated with an ECP-equipped train are realized. Specifically, the cars responding directly to the EOT without waiting for a command from the ECP HOT command yields a shorter stopping distance; a reduction of in-train forces; reduced wheel, brake shoe, and draft gear wear; and a reduction in the amount of brake system air utilized to recover from the brake application, thereby minimizing down-time. 
     With existing systems, a pneumatic emergency on the helper locomotive would result in the EOT activating its dump valve, and the brake pipe of the train being exhausted. All of the cars in the train would apply their brakes to an emergency level, but not at the same time. The cars nearest the EOT would apply their brakes the quickest. Eventually a few cars would broadcast that they were in a pneumatic emergency state, and the rest of the cars would apply their brakes to an emergency level. During the time when the brake pipe was exhausted, the reservoir levels on the car would remain constant at the equalization level, and would not rise. Any nominal pneumatic leaks on the cars, as is common to some level, would cause the reservoir levels to slowly drain down. 
     Recovery from the pneumatic emergency requires that the brake pipe be fully charged, and that all of the reservoirs on the cars be replenished. Depending on the length of the train, this recovery may take more than 15 minutes. By implementing the system and method of the present invention, the ECP EOT would hold-off activating the dump valve in lieu of transmitting an ECP EOT emergency brake request message over the ECP network that causes all of the cars to immediately activate their brakes. The activation of the brakes on the car will occur faster than with existing systems, resulting in a shorter stopping distance. Assuming the ECP HEU received the ECP EOT emergency brake request message and responded with an ECP EOT brake command message, the ECP EOT will refrain from activating the EOT dump valve and the brake pipe will remain charged. Since the brake pipe remains charged, all of the reservoirs on the cars in the train will pull air from the brake pipe and fully charge their reservoirs. Any nominal pneumatic leaks on the cars, as is common to some level, will be replenished with air from the brake pipe. Recovery from the helper emergency can occur as soon as the ECP logic allows it, without having to wait for either the brake pipe or the reservoirs on the cars in the train, to recharge. Accordingly, the present invention provides certain benefits and improvements for addressing pneumatic emergencies in helper locomotives. 
     These and other features and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic of one embodiment of a system for addressing a pneumatic emergency initiated by a helper locomotive associated with a train, in accordance with the principles of the present invention; 
         FIG. 2  is a schematic of one embodiment of an EOT unit, in accordance with the present invention; and 
         FIG. 3  is a flowchart outlining the one preferred operational sequence, in accordance with the principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     For purposes of the description hereinafter, the terms “end”, “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, “longitudinal” and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting. Further any of the steps, functions, or determinations can be made by any suitable computing arrangement or processor, whether a standalone computer or a programming interface, module, software, firmware, or other code integrated with or implemented on an existing computing device or processor of any of the units discussed hereinafter. 
       FIG. 1  depicts a schematic of one preferred and non-limiting embodiment of a system  10  for addressing a pneumatic emergency initiated by a helper locomotive  12  associated with a train  14 . The train  14  includes a locomotive  16  and one or more cars  18  sequentially coupled thereto. The last car  18  includes an end-of-train (EOT) unit  20  and the locomotive  16  includes an electronically controlled pneumatic (ECP) head-end-unit (HEU)  26 , all communicatively connected via an electronically controlled pneumatic (ECP) messaging network (whether in hard-wired or wireless form). The HOT locomotive  16  is mechanically coupled (via mechanical coupler  60 ) to the first car  18 , adjacent cars  18  are mechanically coupled together, and the helper locomotive  12  is mechanically coupled to the last car  18  (and has a physical separation of the brake pipe). The helper locomotive  12  preferably includes radio-based helper equipment  24  that communicates over an EOT radio network (preferably in wireless form) to the EOT unit  20  mounted on the last car  18 . It is to be understood that functionality incorporated in the head-of-train HEU  26  may be facilitating or encompassed by respective separate components connected to and/or configured to interface with the HEU  26 . 
     The train  14  includes an ECP trainline  28  communicatively connecting an ECP controller  30  of each car  18  to the ECP messaging network and, thereby, the HEU controller  26 . The train  14  also includes a brake pipe  32  running the length of the train  14 , which connects each car  18  with an adjacent car  18 , and is terminated with the EOT unit  20  at the last car  18 . The helper locomotive  12  may be a pusher locomotive coupled to an end of the train  14  without a physical connection to the brake pipe  32  of the train  14 . 
     The radio-based helper equipment  24  of the helper locomotive  12  is configured to transmit a brake pipe emergency dump request message on the ECP messaging network. It is noted that ECP messages preferably occur only on the wired ECP network, while messages from the helper locomotive  12  occur over the radio-based EOT network. The HEU  26  of the HOT locomotive  16  is configured to receive an ECP emergency brake request message (which is a message or includes content that requests that the train  14  be stopped and/or that identifies that the helper locomotive  12  has gone into a pneumatic emergency). The HEU  26  of the HOT locomotive  16  is also configured to, in response to receipt of the ECP emergency brake request message, transmit an ECP HOT brake command message on the ECP messaging network to at least one, and preferably, each ECP controller  30  and the EOT unit  20 . One example of an ECP HOT brake command message is a train brake command of 120%, or a TBC=120% command. As is known in the art, a TBC=120% command corresponds to an ECP emergency brake application, as is discussed in publication AAR 54200: ECP ( Cable - Based Brake System Performance Requirements ), the contents of which is incorporated herein by reference in its entirety. However, it is to be understood that other suitable degrees of braking may be associated with the ECP HOT brake command message. It is further to be understood that existing HEU  26  may be programmed to provide the aforementioned functionality. 
       FIG. 2  is a schematic of one preferred and non-limiting embodiment of the EOT unit  20 . According to this embodiment, the EOT unit  20  includes a housing  34  containing a processor  36 , a transmitter  37 , and a receiver  38 , all communicatively connected to an antenna  39 . It is to be understood that the EOT unit  20  may include the necessary components (e.g., storage medium, circuitry, interface, software/firmware, and the like) for providing the fundamental functionality of any existing EOT unit. Existing EOT units and associated components are described in one or more of U.S. Pat. Nos. 4,487,060; 4,885,689; 5,016,840; 5,190,359; 5,235,849; 5,267,473; 5,383,717; and 5,873,638, all of which are incorporated herein by reference in their entirety. The EOT unit  20  also includes a brake pipe dump valve  40  in fluid communication with the brake pipe  32  of the train  14 . The EOT unit  20  may be connected to the ECP trainline  28 , as shown in  FIG. 1 . As is known in the art, receipt of an appropriate signal at the EOT unit  20  results in appropriate mechanisms opening the brake pipe dump valve  40 , resulting in release of the air along the entire brake pipe  32  of the train  14 . 
     The receiver  38  and associated hardware are configured to receive a brake pipe emergency dump command message and to send the information to the processor  36 . The processor  36  and associated software are configured to send an ECP HOT brake request message over the ECP trainline  28  to the cars (e.g., the ECP controllers  30  of each car) and to the ECP HEU  26 . Further, the processor  36  and associated software operating thereon are configured to determine if the ECP HOT brake request message has been received within a predetermined period of time after transmission of the ECP emergency brake request message. 
     In one preferred and non-limiting embodiment, the predetermined period of time may be in the range of about 1 second to about 10 seconds, and preferably in the range of about 3 seconds to about 5 seconds. However, it is to be understood that any suitable time in any suitable time measuring unit may be used in connection with the present invention. It is to be further understood that a suitable time would preferably be a time period in which it is likely or determined that an ECP HOT brake command message should have already been transmitted and been received. The predetermined period of time may be pre-programmed in the EOT unit or may be dynamically modified or programmed based on a per-situation basis before or during train operation, based on certain conditions, such as train parameters, operational conditions, environmental conditions, computer logic assessments, etc. The processor  36  and associated software are also configured to open the brake pipe dump valve  40  if a determination is made that the ECP HOT brake command message has not been received within the predetermined period of time. 
     A method for improving braking safety and reducing brake system recovery time in the ECP-equipped train  14  after transmission of a brake pipe emergency dump command message by the helper locomotive  12  associated with the train  14  will now be discussed in accordance with one preferred and non-limiting embodiment of the present invention. With continued reference to  FIGS. 1 and 2 ,  FIG. 3  depicts a flowchart for illustrating the operational steps in implementing one embodiment of the present invention. If the engineer on the helper locomotive  12  is aware of a situation affecting the train  14  that would require an emergency brake application, the engineer initiates a brake pipe emergency dump command. Specifically, the radio-based helper equipment  24  of the helper locomotive  12  transmits the brake pipe emergency dump command message to the EOT unit  20  of the car  18  of the train  14 , as shown in step  50 . The EOT unit  20  receives the brake pipe emergency dump command message at step  51  and, in response thereto, transmits the ECP emergency brake request message to the HEU  26  of the locomotive  16  of the train  14 , as shown in step  52 . 
     Thereafter, as shown in step  53 , the EOT unit  20  waits a predetermined period of time after transmitting the ECP emergency brake request message. Appropriate logic in the EOT unit  20 , as provided for by the processor  36  and associated software operating thereon, determines whether or not the ECP HOT brake command message (e.g., TBC=120% or some lesser or reduced brake command) has been received at the EOT unit  20  within the predetermined period of time, as shown in step  54 . As shown in step  55 , if the ECP HOT brake command message was received by the EOT unit  20  within the predetermined period of time, the EOT unit  20  does not open the brake pipe dump valve  40  because the processor  36  has received confirmation that ECP braking (e.g., TBC=120% or some lesser or reduced brake command) has been initiated by the locomotive  16 . This results only in a partial depletion of the quantity of air in the car reservoirs needed to apply the brakes, as opposed to depletion of the air in the brake pipe  32 . Further, while in an ECP brake application, the car reservoirs will begin to charge back to their full capacity from the charged brake pipe  32 . 
     In contrast, as shown in step  56 , if the ECP HOT brake command message was not received by the EOT unit  20  within the predetermined period of time, the EOT unit  20  opens the brake pipe dump valve  40  because it is under the assumption that the locomotive  16  did not receive the ECP emergency braking request message or could not initiate ECP braking. This results in a traditional EOT brake pipe emergency dump command to be executed at the EOT unit  20 , causing all air in the brake pipe  32  to be exhausted to atmosphere, and associated car reservoirs to equalize with the brake cylinder. In this case, the car reservoirs will not begin to recharge until the brake pipe is recharged by the operator. 
     In this manner, the present invention provides a system and method for improving braking safety and reducing brake system recovery time in an ECP-equipped train after transmission of a brake pipe emergency dump command message by a helper locomotive associated with the train. 
     Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.