U.S. patent application number 09/877020 was filed with the patent office on 2003-01-09 for method of determining maximum service brake reduction.
This patent application is currently assigned to New York Air Brake Corporation. Invention is credited to Hawthorne, Michael J., Peterson, Edmund R. JR..
Application Number | 20030009274 09/877020 |
Document ID | / |
Family ID | 25369088 |
Filed Date | 2003-01-09 |
United States Patent
Application |
20030009274 |
Kind Code |
A1 |
Peterson, Edmund R. JR. ; et
al. |
January 9, 2003 |
METHOD OF DETERMINING MAXIMUM SERVICE BRAKE REDUCTION
Abstract
A method of and a system for determining a maximum brake pipe
service reduction in the brake system of a train having a pneumatic
brake on each car connected to a brake pipe which is controlled by
a brake pipe controller. The method includes determining the status
of the brake system throughout the train and determining a maximum
brake pipe reduction for the brake pipe controller, using the
status of the brake system, above which further reduction will not
result in further brake application in the train. The determined
maximum brake pipe reduction is displayed by itself or in
combination with the brake pipe reduction produced by the brake
pipe controller and/or used for automatic control
Inventors: |
Peterson, Edmund R. JR.;
(Leesburg, FL) ; Hawthorne, Michael J.;
(Watertown, NY) |
Correspondence
Address: |
BARNES & THORNBURG
750 17TH STREET NW
SUITE 900
WASHINGTON
DC
20006
US
|
Assignee: |
New York Air Brake
Corporation
|
Family ID: |
25369088 |
Appl. No.: |
09/877020 |
Filed: |
June 11, 2001 |
Current U.S.
Class: |
701/70 ;
701/19 |
Current CPC
Class: |
B60T 17/228 20130101;
B60T 15/22 20130101; B60T 13/665 20130101 |
Class at
Publication: |
701/70 ;
701/19 |
International
Class: |
G06F 017/00 |
Claims
In the claims:
1. A method of determining maximum brake pipe reduction in a brake
system of a train having a pneumatic brake on each car connected to
a train brake pipe which is controlled by a brake pipe controller,
the method comprising: determining status of the brake system
through out the train; and determining, using the status of the
brake system, a maximum brake pipe reduction for the brake pipe
controller above which further reduction will not result in further
brake application in the train.
2. A method according to claim 1, including displaying the
determined maximum brake pipe reduction.
3. A method according to claim 1, wherein determining the status
includes determining equalization pressure of the brake system at
each car.
4. A method according to claim 3, wherein determining the
equalization pressure for each car is determined as a function of
the pressures and volumes of a reservoir and a brake cylinder of
each car.
5. A method according to claim 3, wherein determining the maximum
brake pipe reduction includes determining the minimum determined
car equalization pressure in the brake system, and determining the
maximum brake pipe reduction for the brake pipe controller using
the minimum determined car equalization pressure.
6. A method according to claim 1, wherein determining the status
includes determining equalization pressure of the brake system at
each car; and determining the maximum brake pipe reduction includes
determining the minimum determined car equalization pressure in the
brake system and using the minimum determined car equalization
pressure and brake pipe regulation pressure.
7. A method according to claim 1, wherein determining the status
includes determining a minimum equalization pressure of the brake
system; and the maximum brake pipe reduction is determined using
the minimum car equalization pressure.
8. A method according to claim 7, wherein the maximum brake pipe
reduction is determined using the minimum car equalization pressure
if the minimum car equalization pressure is greater than a first
pressure value and using the first pressure if the minimum car
equalization pressure is less than the first pressure value.
9. A method according to claim 8, wherein the first pressure value
is set to a minimum pressure value required for emergency operation
of the braking system.
10. A method according to claim 1, including determining a
requested brake pipe reduction; and indicating if the requested
brake pipe reduction is more than the determined maximum brake pipe
reduction.
11. A method according to claim 1, including determining a
requested brake pipe reduction; and displaying the determined
maximum brake pipe reduction if the requested brake pipe reduction
is greater than the determined maximum brake pipe reduction and
displaying the requested brake pipe reduction if the requested
brake pipe reduction is less than the determined maximum brake pipe
reduction.
12. A method according to claim 10, including controlling the brake
pipe controller to the displayed brake pipe reduction.
13. A method according to claim 1, including determining a
requested brake pipe reduction; and controlling the brake pipe
controller to the determined maximum brake pipe reduction if the
requested brake pipe reduction is greater than the determined
maximum brake pipe reduction and controlling the brake pipe
controller to the requested brake pipe reduction if the requested
brake pipe reduction is less than the determined maximum brake pipe
reduction.
14. A method according to claim 1, wherein the brake pipe
controller is in a locomotive of the train and the method is
performed on a computer in the locomotive.
15. A method according to claim 1, wherein the status of the brake
system is determined using train brake system modeling.
16. A method according to claim 1, wherein determining the status
of the brake system includes each car reporting the status of the
brake system of the car.
17. A method according to claim 1, wherein determining the status
of the brake system includes determining brake cylinder pressure
and at least one of reservoir or brake pipe pressure for each
car.
18. A method according to claim 1, wherein the method is repeated
at least after each brake pipe pressure increase.
19. A method of determining maximum brake pipe reduction in a brake
system of a train having a pneumatic brake on each car connected to
a train brake pipe which is controlled by a brake pipe controller,
the method comprising: determining equalization pressure of the
brake system at each car; determining the minimum determined car
equalization pressure in the brake system; and determining, using
the minimum determined car equalization pressure, a maximum brake
pipe reduction for the brake pipe controller above which further
reduction will not result in further brake application in the
train.
20. A method according to claim 19, wherein determining the
equalization pressure for each car is determined as a function of
the pressures and volumes of a reservoir and a brake cylinder of
each car.
21. A method according to claim 19, wherein the maximum brake pipe
reduction is determined using the minimum car equalization pressure
if the minimum car equalization pressure is greater than a first
pressure value and using the first pressure if the minimum car
equalization pressure is less than the first pressure value.
22. A method according to claim 19, including displaying the
determined maximum brake pipe reduction.
23. A method according to claim 19, including determining a
requested brake pipe reduction; and indicating if the requested
brake pipe reduction is more than the determined maximum brake pipe
reduction.
24. A method according to claim 19, including determining a
requested brake pipe reduction; and displaying the determined
maximum brake pipe reduction if the requested brake pipe reduction
is greater than the determined maximum brake pipe reduction and
displaying the requested brake pipe reduction if the requested
brake pipe reduction is less than the determined maximum brake pipe
reduction.
25. A method according to claim 19, including determining a
requested brake pipe reduction; and controlling the brake pipe
controller to the determined maximum brake pipe reduction if the
requested brake pipe reduction is greater than the determined
maximum brake pipe reduction and controlling the brake pipe
controller to the requested brake pipe reduction if the requested
brake pipe reduction is less than the determined maximum brake pipe
reduction.
26. A method of determining maximum brake pipe reduction in a brake
system of a train having a pneumatic brake on each car connected to
a train brake pipe which is controlled by a brake pipe controller,
the method comprising: determining a minimum car equalization
pressure of the brake system; determining a maximum brake pipe
reduction using the minimum car equalization pressure if the
minimum car equalization pressure is greater than a first pressure
value and using the first pressure if the minimum car equalization
pressure is less than the first pressure value.
27. A method according to claim 26, including displaying the
determined maximum brake pipe reduction.
28. A method of determining maximum brake pipe reduction in a brake
system of a train having a pneumatic brake on each car connected to
a train brake pipe which is controlled by a brake pipe controller,
the method comprising: determining a minimum car equalization
pressure of the brake system; determining, using the minimum
determined car equalization pressure, a maximum brake pipe
reduction for the brake pipe controller; determining a requested
brake pipe reduction; and indicating if the requested brake pipe
reduction is more than the determined maximum brake pipe
reduction.
29. A method of displaying maximum brake pipe reduction in a brake
system of a train having a pneumatic brake on each car connected to
a train brake pipe which is controlled by a brake pipe controller,
the method comprising: determining a minimum car equalization
pressure of the brake system; determining, using the minimum
determined car equalization pressure, a maximum brake pipe
reduction for the brake pipe controller; determining a requested
brake pipe reduction; and displaying the determined maximum brake
pipe reduction if the requested brake pipe reduction is greater
than the determined maximum brake pipe reduction and displaying the
requested brake pipe reduction if the requested brake pipe
reduction is less than the determined maximum brake pipe
reduction.
30. A method of controlling maximum brake pipe reduction in a brake
system of a train having a pneumatic brake on each car connected to
a train brake pipe which is controlled by a brake pipe controller,
the method comprising: determining a minimum car equalization
pressure of the brake system; determining, using the minimum
determined car equalization pressure, a maximum brake pipe
reduction for the brake pipe controller; determining a requested
brake pipe reduction; and controlling the brake pipe controller to
the determined maximum brake pipe reduction if the requested brake
pipe reduction is greater than the determined maximum brake pipe
reduction and controlling the brake pipe controller to the
requested brake pipe reduction if the requested brake pipe
reduction is less than the determined maximum brake pipe
reduction.
31. A locomotive display system for a train including a brake
system having a pneumatic brake on each car connected to a train
brake pipe which is controlled by a brake pipe controller, the
display system comprising: a display of brake pipe reduction at the
locomotive; and a display of a maximum brake pipe reduction above
which further reduction will not result in further brake
application in the train.
32. A system according to claim 31, wherein the brake pipe
reduction is an analog display and the maximum brake pipe reduction
is an indication on the analog display.
33. A system according to claim 32, wherein the brake pipe
reduction is also digitally displayed.
34. A system according to claim 31, including means for determining
the maximum brake pipe reduction using the brake system status
throughout the train.
35. A system according to claim 31, including means for determining
a minimum equalization pressure in the brake system and determining
the maximum brake pipe reduction using the determined minimum
equalization pressure.
36. A system according to claim 35, wherein the means determines
the maximum brake pipe reduction using the minimum car equalization
pressure if the minimum car equalization pressure is greater than a
first pressure value and using the first pressure if the minimum
car equalization pressure is less than the first pressure
value.
37. A system according to claim 31, including means for determining
the equalization pressure of each car in the train, determining a
minimum determined equalization pressure in the brake system, and
determining the maximum brake pipe reduction using the determined
minimum determined equalization pressure.
38. A system according to claim 31, including means for determining
a requested brake pipe reduction and controlling the brake pipe
controller to the determined maximum brake pipe reduction if the
requested brake pipe reduction is greater than the determined
maximum brake pipe reduction and controlling the brake pipe
controller to the requested brake pipe reduction if the requested
brake pipe reduction is less than the determined maximum brake pipe
reduction.
39. A locomotive control system for a train including a brake
system having a pneumatic brake on each car connected to a train
brake pipe which is controlled by a brake pipe controller, the
system comprising: means for determining a minimum car equalization
pressure of the brake system; means for determining, using the
minimum determined car equalization pressure, a maximum brake pipe
reduction for the brake pipe controller; means for determining a
requested brake pipe reduction; and means for controlling the brake
pipe controller to the determined maximum brake pipe reduction if
the requested brake pipe reduction is greater than the determined
maximum brake pipe reduction and controlling the brake pipe
controller to the requested brake pipe reduction if the requested
brake pipe reduction is less than the determined maximum brake pipe
reduction.
40. A system according to claim 39, wherein the means for
determining a maximum brake pipe reduction uses the minimum car
equalization pressure if the minimum car equalization pressure is
greater than a first pressure value and uses the first pressure if
the minimum car equalization pressure is less than the first
pressure value.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
[0001] The present invention relates generally to locomotive
display and more specifically to a method of determining maximum
service brake reduction and its use with, for example, a Locomotive
Engineers Assist Display and Event Recorder (LEADER) system.
[0002] The LEADER System, as described in U.S. Pat. No. 6,144,901,
is a real-time, enhanced version of the Train Dynamics Analyzer
(TDA), a long standing Locomotive Engineer training tool offered by
the Train Dynamics Services Group of New York Air Brake. The LEADER
system has the ability to display a real-time or "live"
representation of a train on the current track, the trackage ahead,
the dynamic interaction of the cars and locomotives (both head end
and remote), and the current state of the pneumatic brake system.
As a tool for the Locomotive Engineer, the LEADER system will allow
insight into the effect of throttle changes and brake applications
throughout the train providing feedback and information to the
Locomotive Engineer not currently available. The information the
LEADER system offers provides an opportunity for both safer and
more efficient train handling leading to enormous potential
economic benefits.
[0003] The LEADER System has all the necessary information to
predict the future state of the train given a range of future
command changes (what if scenarios). With this ability, LEADER can
assist the railroads in identifying and implementing a desired
operating goal; minimize time to destination, maximize fuel
efficiency, minimize in train forces, (etc.) or a weighted
combination thereof. LEADER will perform calculations based on the
operational goal and the current state of the train to make
recommendations to the Locomotive Crew on what operating changes
will best achieve these goals.
[0004] The TDA functionality was enhanced to assist in training
Locomotive Engineer how to better handle their trains. Designs of
simulators with math models are shown in U.S. Pat. Nos. 4,041,283;
4,827,438 and 4,853,883. Further capability was added to
investigate accidents by playing the event recorder data through
the TDA, monitoring critical physical parameters. Through the years
data was collected from instrumented trains and laboratory
experiments, allowing the models used by the TDA to be refined. On
board data collection for off-loading is shown in U.S. Pat. Nos.
4,561,057 and 4,794,548.
[0005] As more Locomotive Engineers became familiar with the TDA
display through training sessions, it became apparent that a real
time version of the TDA in the cab of a locomotive would offer
substantial benefits in improved train handling. Improved train
handling would in turn foster safety and economic benefits.
Technological limitations prevented the realization of LEADER for a
number of years, but modern levels of computer processing power,
decreased size of electronics, increase communication capability
and increase size and readability of flat panel color displays has
made the LEADER system a reality. Earlier designs for on board
computer controllers is shown in U.S. Pat. No. 4,042,810 with a
description of math models. The LEADER system provides safe and
effective control of a train through display or control of the
dynamically changing parameters.
[0006] The conventional air brakes and air brake systems in
conventional freight trains, pneumatic storage reservoir on each
freight car, called an auxiliary reservoir is charged by the brake
pipe extending throughout the train. The compressor on the
locomotive charges the brake pipe through a pressure regulating
system. A brake application is achieved, following the charging
action, by reducing the pressure in the brake pipe below the level
of charge. When the brake pipe pressure is sufficiently reduced,
the control valve on each car supplies air from the auxiliary
reservoir to the car's brake cylinder. The amount of air supplied
is a function of the brake pipe reduction. During an application,
if the reduced pressure in the reservoir becomes equal to the
increased pressure in the brake cylinder, no further air flow will
occur. The pressure is thus equalized and is referred to as
equalization pressure. If brake pipe pressure is reduced below the
equalization pressure for that individual car, no further brake
cylinder pressure is achieved. Brake pipe pressure reduction below
the equalization pressure are known as an "over-reduction." This
has the effect of wasting compressed air in the brake pipe
increasing the time required to recharge the train brake system and
release the brakes by the recharging. In actual freight operations,
the brake pipe pressure that exists at each car may vary
significantly with time and car location. It may take a very few
minutes to charge the first car in a train to regulation level. It
may take up to an hour or longer to charge the last car.
[0007] It is impossible for a locomotive engineer to calculate and
keep track of the maximum reduction that can be made during brake
applications. Thus the engineer can easily produce an over
reduction wasting compressed air and increased time required to
release and recharge the train brake system. This can result in a
dangerous situation as often times a quick release and then
recovery of the brake application is required to properly control
the train. Thus there is a need for a system to inform the engineer
when all cars have come to their equalization pressure and will
achieve no additional braking for a further reduction of the brake
pipe.
[0008] The present invention provides a method of determining the
maximum brake pipe reduction including the steps of determining the
status of the brake system throughout the train. The next step is
determining, using the status of the brake system, maximum brake
pipe reduction above which further reduction will not result in
further brake application in the train. The determined maximum
brake pipe reduction may be displayed or used to control the brake
pipe. The status of the brake system throughout the train is
determined by determining equalization pressure of the brake system
in each car. This may be by a mathematical models or actual
measurements. The equalization pressures are a function of
pressures and volumes of the reservoir and brake cylinder of the
individual cars.
[0009] The process can also include determining the minimum
determined car equalization pressure throughout the train and
determining the maximum brake reduction using the minimum
determined car equalization pressure. If the minimum car
equalization pressure for the train is greater than a first
pressure value, the minimum equalization pressure is used to
determine the maximum brake pipe reduction. If the minimum car
equalization pressure is less than the first pressure value, the
first pressure value is used in determining the maximum brake pipe
reduction. The first pressure value is generally set to a minimum
pressure required for an emergency operation of the brake system.
Preferably the method is repeated after each brake pipe pressure
increase. Recalculation is necessary because it changes the
original dynamics and calculation of equalization pressure for each
car.
[0010] Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a block diagram of the system components of a
locomotive assist display and event recorder system according to
the principles of the present invention.
[0012] FIGS. 2A and 2B are a LEADER display incorporating the
principles of the present invention.
[0013] FIG. 3 is a flow chart of a first embodiment of a method for
determining maximum service brake reduction according to the
principles of the present invention.
[0014] FIG. 4 is a flow chart of a second embodiment of a method
for determining maximum service brake reduction with enforcement
according to the principles of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Math models of the LEADER System, monitors parameters and
performs calculations based on the current energy state of the
train to create a real-time display of train dynamics. The power of
LEADER resides in its ability to provide information allowing the
crew to better control the train, minimizing loss of energy. Loss
of energy via over-braking represents fuel unnecessarily consumed.
Energy imparted to the cargo of the train represents potential
damage to lading, equipment and rail. Both phenomena are
undesirable and addressable with LEADER.
[0016] The LEADER system is comprised of a number of subsystems
each with specific duties. FIG. 1 shows a generic LEADER
architecture. The user interface of the LEADER System is the
real-time display which shows a graphical and numerical
representation of the current state of the train as shown in FIGS.
2A and 2B. Radio communication is established between the lead
locomotive, the trailing locomotives in the lead consist, and
locomotives in the remote consist to report the necessary
parameters from each of these locomotives necessary to perform
LEADER Calculations. Consist information is entered via the key pad
on the real-time display, a wired communication source (laptop PC
or removable storage device) or via wayside radio communication.
Position is determined from wheel movement sensors and a Global
Positioning System (GPS). The Input/Output (I/O) Concentrator
gathers all of the various locomotive parameters necessary for
LEADER algorithm calculations and reports the information to the
LEADER Computer. The LEADER Processor, a high throughput capacity
computer platform using a Real Time Operating System (RTOS), then
performs the calculations required by the LEADER algorithms and the
real-time display is updated. All of these sub-systems combine to
form the LEADER System.
[0017] Each locomotive in a LEADER train will require at a minimum,
the I/O Concentrator with communication capability to the head end.
A LEADER Processor and Display are only required for the lead
locomotive. The decision to equip all locomotives with a full
LEADER installation (Processor, Display in addition to the I/O
Concentrator) should be based on the Railroads ability to
permanently designate a locomotive as lead or trail in its
duties.
[0018] The development of LEADER began over 20 years ago with early
efforts to create the Train Dynamics Analyzer (TDA), a computer
math model used to predict in-train forces. The train dynamic
modeling techniques and algorithms embodied in the TDA are
described in U.S. Pat. No. 4,041,283. A more detailed description
of the LEADER system is found in U.S. Pat. No. 6,144,901.
[0019] FIGS. 2A and 2B show a "static" LEADER display. Each LEADER
feature is identified by a block which points to the appropriate
screen location. The sections following use the same paragraph
number as the identification block detail the operation of each
feature.
[0020] The LEADER Display shown in FIGS. 2A and 2B represents one
particular configuration for the display of LEADER information. The
display format can be customized on customer request by adding
information, removing information, changing the color scheme,
rearranging the position of the sections of information, and/or
varying the size of any particular graphic.
[0021] In the following descriptions of features on the LEADER
Display the term function will be used to describe the plot of the
magnitude of a particular parameter across the length of the train
varying with time. Sections are numbered to match the
identification blocks of FIG. 2.
[0022] 2.1 Track Profile
[0023] The top portion of the LEADER Display shows the track
profile in three views. The train consist is represented with
different colored blocks for the locomotive units and for the cars.
The length of the displayed train is proportional to the length of
the actual train. Milepost marks are represented by lines running
vertically through the track profile portion of the display.
[0024] 2.2 Horizontal View of Track
[0025] The horizontal view of the track profile shows the grade on
which the train is currently positioned and the grade of the track
profile for a number of miles ahead. The horizontal view of the
track profile will show the position of the entire train on the
track, both current location and geographic shape (uphill or
downhill) as a vertical slice of the track profile in
real-time.
[0026] 2.3 Track Curvature Representation
[0027] The top graphic of the track profile section is made up of
blocks that represent track curvature. A block above the dividing
line represents a curve to the right, a block below the dividing
line represents a curve to the left. The longer the block the
longer the curve. The higher the block the more severe the
curve.
[0028] 2.4 Overhead View/Supplemental Information
[0029] Just above the horizontal view is the overhead view. This
view incorporates symbols to represent track structures such as
crossings, signals, overpasses, underpasses, and sidings.
[0030] 2.5 In-Train Forces
[0031] Directly below the train represented on the LEADER display
is the portion of the screen dedicated to showing in-train forces.
All in-train forces are displayed as a graphic that maps to each
car in the train. Follow any point on any of the force functions
straight up the display and it will intersect with a point on the
train where that particular level of force is currently present.
The graphics can be identified as the draft/buff magnitude force
functions.
[0032] The draft/buff force graphic represents draft forces as a
function above the 0 kilo-pound line and buff forces as a function
below the 0 kilo-pound line. Draft and buff forces can be divided
into two categories, steady state and transient. Steady state
forces are shown, in general, by a smooth, relatively slow changing
function. Transient draft and buff forces (run-in/run-out or slack
induced forces) are shown by "spikes" of force that travel through
the train. The LEADER system accurately calculates and displays
both. Slack induced forces represent momentum transfers between the
cars resulting in potential lading and car damage.
[0033] 2.6 Brake Cylinder Pressure
[0034] Directly below the force graphics is a function that
represent brake cylinder pressure throughout the train. Again,
these functions map to a location in the train representation
directly above. Because the functions are real-time representations
of the brake system, it is possible to monitor a brake application
or release as it travels through the entire train.
[0035] 2.7 Trajectory/Telemetry Information
[0036] The lower right and lower center sections of the screen have
real time trajectory and status information displayed in digital
format.
[0037] 2.7.1 Head End Information
[0038] Location is a digital representation of mile marker location
of the head end locomotive. Grade is the grade of the track at the
location of the head end locomotive. Curve is the degree of
curvature of the track at the location of the head end
locomotive.
[0039] 2.7.2 Speed is shown as a digital read out of the speed of
the head end locomotive at each instant in time.
[0040] 2.7.3 Acceleration is shown as a digital read out
representing the acceleration of the head end locomotive at each
instant in time.
[0041] 2.7.4 Current Speed Limit is shown as a digital read out of
the speed limit for the current position of the head end
locomotive.
[0042] 2.7.5 Fuel is the amount of fuel consumed since the counter
was last reset.
[0043] 2.7.6 Time is the digital read out of the current time.
[0044] 2.7.7 Brake Pipe Reduction (or EP Brake Command) This
graphic takes on two roles; one for conventional pneumatic brake
equipped trains and one for EP Brake equipped trains. In
Conventional, the graphic is a digital read out followed by an
analog bar graph 2.8.1 representing the brake pipe pressure
reduction at the head end locomotive at each instant in time. The
LEADER system has the capability to support trains equipped with EP
Brake Systems rather than conventional displacement valves. In an
EP equipped train the graphic is a digital read out followed by an
analog bar graph representing the percent of brake commanded to the
EP System.
[0045] 2.7.8 Draw Bar Forces is a digital read out followed by an
analog bar graph representing the instantaneous locomotive draw bar
force of the last locomotive of the lead consist.
[0046] 2.8.1 Pneumatic Brake Reduction is shown as an analog bar
graph representing the brake pipe pressure reduction at the head
end locomotive at each instant in time.
[0047] 2.8.2 Minimum Safe Pneumatic Brake Reduction is of interest
for safe train operation. As brake applications are applied and
released the charge state of the pneumatic brake system can become
such that an undesired release of brakes will occur if the next
brake application requested is not deep enough. The LEADER system
will calculate the safe brake application level and visually
display a minimum target on the Brake Reduction bar graph. If the
brake application requested is not deep enough, a visual warning
will be posted by the LEADER display. This is described in detail
in U.S. patent application Ser. No. 09/152,244 filed Sep. 11,
1998.
[0048] 2.8.3 Maximum Pneumatic Brake Reduction is of interest for
safe train operation. As the auxiliary reservoir reaches the
equalization pressure for its brake cylinder, further reduction of
the brake pipe will not produce any additional braking on that car.
Once all the car's auxiliary reservoirs have reached their
equalization pressure, further reduction of the brake pipe will
produce no additional braking on the train. Further reduction will
only waste brake pipe pressure. The LEADER system will calculate a
maximum safe brake pipe reduction and visually displays if on the
brake pipe reduction bar graph. If the brake pipe request is
greater than the maximum target, visual warning will be posted by
the LEADER display.
[0049] The LEADER display is equipped with eight function keys at
the bottom of the display. The definition of each function key is
shown in the representation of the key on the LCD panel directly
above it. The function keys allow user input to the system,
accessing various setup and configuration menus and querying
information from the LEADER system.
[0050] The LEADER system is capable of three operating modes, each
building on the previous mode. The three modes advance the LEADER
system from a real time display passively providing information to
the locomotive engineer (information only mode) to a LEADER system
that will make suggestions to the locomotive engineer on how to
better handle the train (driver assist mode) and finally to a
control system that is capable of issuing commands to optimally
control the locomotive (cruse control mode).
[0051] In the information only mode, the locomotive engineer makes
all of the decisions and solely activates the various control
systems in a manual mode. The LEADER system provides information to
the engineer that is not currently available to him/her to use to
manage various locomotive control systems. In driver assist mode,
the LEADER system determines and displays the optimum locomotive
power dynamic brake throttle setting and the locomotive and car
brake control settings. These settings are determined for the head
end locomotives and the remotely controlled locomotives. These
recommendations are desired settings displayed to the locomotive
engineer who can then elect to manually move the various controls
to achieve these settings. In the cruise control mode, LEADER
derived settings are used to automatically control the locomotive
power and braking systems, the train brake system of each car and
ancillary systems which effect train movement. The locomotive
engineer serves as an operational supervisor with the ability to
manually override the cruise control. Cruise control can also be
produced by communication links between the LEADER and the railroad
central traffic control center.
[0052] The LEADER system provides a maximum brake reduction using,
for example, the flow charts of FIG. 3 or 4. As illustrated in the
flow chart of FIG. 3, the state of the brake system throughout the
train is determined from the LEADER algorithms at 10. LEADER inputs
are collected. For example, it measures the locomotive brake
control settings or determined brake requirement, the brake pipe
pressures and the time. The brake pipe pressures may be measured at
each locomotive and the end-of-train device or any other sensor or
smart node throughout the train. Any additional measurement is used
to increase the accuracy of the math model for the pressure in the
train brake system. The data base of the train make up including
car weights and lengths, brake equipment definition and coupler
types etc. is also used.
[0053] The status of the brake pipe system throughout the train is
determined on a vehicle by vehicle basis using brake simulation
models by themselves or in combination with multiple measurements
throughout the train. Depending upon the intelligence levels of the
individual cars, more information can be collected to increase the
accuracy of the simulation models.
[0054] An analysis of each car's equalization pressure and the
minimum equalization pressure for the train is determined. The
equalization pressure is the pressure at which the brake cylinder
and the reservoir pressure, which applies air to the brake
cylinder, for example, auxiliary reservoir pressure, have
equalized. The equalization pressure can be determined by the
following formula: (Boyle's Law):
1 Peq = (Pa*Va+Pc*Vc) / (Va+Vc) Where: Peq=Equalization pressure
Pa=Auxiliary pressure Pc=Brake cylinder pressure Va=Auxiliary
Reservoir volume Vc=Brake Cylinder volume For example: IF: Pa = 70
psi Pc = 0 psi Va = 2500 Cu. in. Vc = 1000 cu. in. THEN: Peq=50
psi
[0055] Next the maximum brake pipe reduction Rmax is determined at
14 or 16. A locomotive engineer controls the extent of brake
application by reducing the brake (brake pipe reduction) pipe
pressure that causes the auxiliary pressure at each freight car to
correspondingly reduce to the same approximate level. The auxiliary
pressure is reduced through a flow of air to the brake cylinder.
The locomotive engineer controls the pressure level that a train is
charged to. The brake pipe regulation pressure typically ranges
from 70 psi to 110 psi. The difference between the regulation
pressure that the train is charged to and the brake pipe pressure
that the brake pipe is reduced to, during a brake application, is
the amount of brake pipe reduction. The amount of reduction is
calculated as follows:
R=Pr-Pb
[0056] Where:
[0057] R=Brake pipe reduction
[0058] Pr=Brake pipe regulation pressure
[0059] Pb=Current brake pipe level
[0060] If the brake pipe pressure is reduced below the equalization
pressures Peq no further brake cylinder pressure is achieved. Brake
pipe pressure reductions R lower than equalization pressure Peq is
an "over reduction", and has the effect of wasting compressed air
and increasing the time required to release and recharge the train
brake system. The maximum reduction that should be made can be
computed as follows:
Rmax=Pr-Peq
[0061] Freight trains have an emergency application, braking mode
which guarantees that the train can be stopped as quickly as
possible. This emergency feature will not reliably operate at brake
pipe pressures below 35 to 45 psi. The maximum brake reduction
should thus be computed as:
Rmax=Pr-Peq(min) (if Peq>Pbmin)
Rmax=Pr-Pbmin (if Peq<Pbmin)
[0062] Where:
[0063] Rmax=recommended maximum reduction
[0064] Pbmin=lowest brake pipe pressure for emergency to
operate
[0065] Peq(min)=minimum equalization pressure in the brake
system
[0066] In actual freight operations, the brake pipe pressure that
exists at each car may vary significantly with time and car
location. It may take a very few minutes to charge the first car in
a train to regulation level but may take up to an hour or longer to
charge the last car.
[0067] It is impossible for a locomotive engineer to calculate and
keep track of the maximum reduction that he should make during
brake applications. The LEADER computer keeps track of the state of
brake pipe and reservoir charge pressures from car to car on a
continuous basis. The resultant Rmax is then reported at 18
continuously to the engineer in a graphical fashion on the LEADER
display as shown in FIG. 2B.
[0068] FIG. 4 illustrates a flow chart for enforcement of the
maximum brake pipe reduction. It can also be used for cruise or
automatic control. The LEADER system monitors locomotive brake
commands at 20. If there is a brake command at 22, then the LEADER
system calculates brake system status, vehicle by vehicle as
illustrated in 24. If there is no brake command, it cycles back to
monitoring locomotive commands at 20. Next there is analysis of
each vehicles equalization pressure Peq and a determination of the
minimum equalization pressure through the train Peq(min). If the
minimum brake equalization pressure Peq(min) is greater than the
lowest brake type pressure for emergency to operate Pbmin as
determined at 28, then the maximum brake pipe reduction Rmax is
equal to the difference of the brake pipe regulation pressure Pr
and the minimum equalization pressure Peq(min) at 32. If the
minimum equalization pressure Peq(min) is equal to or less than the
Pbmin at 28, then the maximum reduction pressure Rmax is the
regulation pressure Pr less the lowest brake pipe pressure for
emergency to operate Pbmin.
[0069] In addition to displaying the maximum reduction Rmax as
2.8.3 in FIG. 2B, it is determined whether the requested brake
command is less than the maximum reduction Rmax at 34. If it is,
the requested brake command is executed and the LEADER display is
updated at 36. If the requested brake command is not less than the
maximum brake pipe reduction Rmax at 34, the operator is alerted to
the requested over reduction at 38. This may be an audio or visual
indication. After the alert, it is determined at 42 whether the
operator took appropriate action based on the railroad rules and
over reduction at 40. If the appropriate action is taken, the
appropriate brake reduction is executed and the LEADER display is
updated at 36. If not, the system automatically adjusts the brake
pipe command to prevent over reduction at 44 and this adjusted
brake command is executed and the displays updated at 36.
[0070] The present method has been carried out wherein the minimum
equalization pressure throughout the brake system or the car having
the minimum equalization pressure is used since this provides
additional breaking even though it may be one car. The railroad may
set other rules for determining the minimum equalization pressure
throughout the train in determining the maximum reduction.
[0071] Since the process of FIGS. 3 and 4 are continuously
performed, the equalization pressure of each car and the brake pipe
values are continuously updated. This will account for any release
of brakes, subsequent to any braking action. With the release of
brakes, the brake cylinder pressure is reduced to atmosphere and
the auxiliary pressure is recharged. This will change the
equalization pressure for each of the cars. Also with the rate of
charging the brake pipe, at any point in time each car may have a
different value and consequently its equalization pressure. It
should also be noted that the LEADER model takes into effect
variations in brake pipe pressure throughout the train due to
reduction for braking or charging for release.
[0072] Although the present invention has been described and
illustrated in detail, it is to be clearly understood that the same
is by way of illustration and example only, and is not to be taken
by way of limitation. The spirit and scope of the present invention
are to be limited only by the terms of the appended claims.
* * * * *