U.S. patent application number 10/034977 was filed with the patent office on 2002-07-11 for feed valve and reference pressure enhancement.
Invention is credited to Deno, Milt, Johnson, Don K., Smith, Eugene A. JR..
Application Number | 20020089232 10/034977 |
Document ID | / |
Family ID | 22983206 |
Filed Date | 2002-07-11 |
United States Patent
Application |
20020089232 |
Kind Code |
A1 |
Smith, Eugene A. JR. ; et
al. |
July 11, 2002 |
Feed valve and reference pressure enhancement
Abstract
A method to facilitate reducing delays in braking applications
in a train using a system. The system includes at least one
computer for executing brake control functions of the train and a
brake pipe that extends along a length of the train for supplying
air for brake operations. The train includes a lead locomotive, at
least one remote locomotive, and at least one railcar. The method
includes sensing a change in airflow in the brake pipe, determining
whether the change in air flow is desired, sensing brake pipe
pressure, and filtering undesired fluctuations in brake pipe
pressure during brake applications based on the determination of
whether a change in airflow is desired.
Inventors: |
Smith, Eugene A. JR.;
(Satellite Beach, FL) ; Deno, Milt; (Melbourne,
FL) ; Johnson, Don K.; (Palm Bay, FL) |
Correspondence
Address: |
John S. Beulick
Armstrong Teasdale LLP
Suite 2600
One Metropolitan Sq.
St. Louis
MN
63102
US
|
Family ID: |
22983206 |
Appl. No.: |
10/034977 |
Filed: |
December 27, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60259030 |
Dec 29, 2000 |
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Current U.S.
Class: |
303/15 ;
303/20 |
Current CPC
Class: |
B60T 13/665 20130101;
B60T 17/228 20130101 |
Class at
Publication: |
303/15 ;
303/20 |
International
Class: |
B60T 007/00 |
Claims
What is claimed is:
1. A method to facilitate reducing delays in braking applications
in a train using a system including at least one computer for
executing brake control functions of the train and a brake pipe
that extends along a length of the train for supplying air for
brake operations, the train including a lead locomotive, at least
one remote locomotive, and at least one railcar, said method
comprising: sensing a change in airflow in the brake pipe;
determining whether the change in airflow is desired; sensing brake
pipe pressure; and filtering undesired fluctuations in brake pipe
pressure during brake applications based on the determination of
whether the change in airflow is desired.
2. A method in accordance with claim 1 wherein the method further
facilitates reducing undesired brake releases in the train, and the
brake pipe includes a plurality of connected brake pipe sections
such that each lead locomotive and remote locomotive in the train
includes a respective brake pipe section that includes a feed valve
cutoff valve and relay valve for controlling a flow of air into
each respective brake pipe section, a brake pipe pressure sensor
for sensing pressure in each respective brake pipe section, and a
brake pipe flow sensor for sensing air flow into the brake pipe,
sensing a change in air flow in the brake pipe comprising
monitoring the air flow in each remote locomotive brake pipe
section.
3. A method in accordance with claim 2 further comprising sensing a
change in air flow in at least one remote locomotive brake pipe
section.
4. A method in accordance with claim 3 further comprising
implementing a feed valve cut-out of the remote locomotive feed
valve upon sensing the change in airflow.
5. A method in accordance with claim 4 wherein determining whether
a change in air flow is desired comprises the step of sending a
verification message from the remote locomotive to at least one of
the lead locomotives upon sensing the change in air flow.
6. A method in accordance with claim 5 further comprising not
receiving a signal from the lead locomotive indicating the change
in airflow is desired.
7. A method in accordance with claim 6 wherein determining whether
a change in air flow is desired comprises: maintaining the feed
valve cut-out of the remote locomotive feed valve; and idling the
remote locomotive.
8. A method in accordance with claim 5 further comprising receiving
a signal from the lead locomotive indicating the change in airflow
is not desired.
9. A method in accordance with claim 8 wherein reacting to the
determination of whether a change in airflow is desired comprises
implementing a feed valve "cut-in" of the remote locomotive feed
valve and allowing the remote locomotive to apply brakes as
commanded by the lead locomotive, wherein the remote locomotive
remains in a commanded traction state.
10. A method in accordance with claim 2 wherein filtering undesired
fluctuations in brake pipe pressure comprises: measuring an initial
pressure in the remote brake pipe section upon receipt of a brake
application command; and setting a reference pressure for the
remote brake pipe section equal to the value of the highest value
of the last seven pressure samples from the brake pipe pressure
sensor.
11. A method in accordance with claim 10 further comprising:
sampling the pressure, at a specified duty cycle, in the remote
brake pipe section; accumulating a sample set for the remote brake
pipe section, the sample set for each new sample consisting of the
last seven samples; and determining a maximum value of the sample
set.
12. A method in accordance with claim 11 further comprising:
comparing the maximum value of the sample set to the reference
pressure; resetting the reference pressure equal to the maximum
value if the maximum value is less than the reference pressure; and
retaining the reference pressure if the maximum value is greater
than the reference pressure.
13. A method in accordance with claim 12 further comprising:
repeating the steps of sampling the pressure, accumulating a sample
set, determining a maximum value, comparing the maximum value,
resetting the reference pressure, and retaining the reference
pressure until the brake pipe pressure for the remote brake pipe
section drops to a specified level; comparing the value of each
sampled pressure to the brake pipe reference pressure after each
sampling; and determining whether an undesired brake release has
occurred in the remote locomotive based on the comparison of each
sampled pressure to the reference pressure.
14. A system to facilitate reducing delays in braking applications
in a train, said system comprising at least one computer for
executing brake control functions of the train and a brake pipe
that extends along a length of the train for supplying air for
brake operations, the train comprising a lead locomotive, at least
one remote locomotive, and at least one railcar, said system
configured to sense a change in airflow in said brake pipe;
determine whether the change in air flow is desired; sense brake
pipe pressure; and filter undesired fluctuations in brake pipe
pressure during brake applications based on the determination of
whether the change in airflow is desired.
15. A system in accordance with claim 14 wherein said system
further facilitates reducing undesired brake releases in the train,
said brake pipe comprises a plurality of connected brake pipe
sections such that each lead locomotive and remote locomotive in
the train comprises a respective brake pipe section that includes a
feed valve cutoff valve and relay for controlling the flow of air
into each said respective brake pipe section, a brake pipe pressure
sensor for sensing pressure in each said respective brake pipe
section, and a brake pipe flow sensor for sensing air flow into the
brake pipe, said system further configured to sense a change in air
flow in said brake pipe, said system configured to monitor the air
flow in each remote locomotive brake pipe section.
16. A system in accordance with claim 15 further configured to
sense a change in air flow in said remote locomotive brake pipe
section.
17. A system in accordance with claim 16, further configured to
implement a feed valve cut-out of said remote locomotive feed valve
upon sensing the change in air flow.
18. A system in accordance with claim 17 wherein to determine
whether the change in air flow is desired, said system configured
to send a verification message from said remote locomotive to at
least one of said lead locomotives upon sensing the change in air
flow.
19. A system in accordance with claim 18 further configured to not
receive a signal from said lead locomotive indicating that the
change in airflow is desired.
20. A system in accordance with claim 19 wherein to react to the
determination of whether the change in air flow is desired, said
system configured to: maintain the feed valve cut-out of said
remote locomotive feed valve; and idle said remote locomotive.
21. A system in accordance with claim 18 further configured to
receive a signal from said lead locomotive indicating the change
airflow is not desired.
22. A system in accordance with claim 21 wherein to react to the
determination of whether a change in airflow is desired, said
system configured to implement a feed valve "cut-in" of said remote
locomotive feed valve, allow the remote locomotive to apply brakes
as commanded by the lead locomotive, wherein the remote locomotive
remains in a commanded traction state.
23. A system in accordance with claim 15 wherein to filter
undesired fluctuations in brake pipe pressure, said system
configured to: measure an initial pressure in said remote brake
pipe section upon receipt of a brake application command; and set a
reference pressure for said remote brake pipe section equal to the
value of the highest value of the last seven pressure samples from
the brake pipe sensor.
24. A system in accordance with claim 23 further configured to:
sample the pressure, at a specified duty cycle, in said remote
brake pipe section; accumulate a sample set for said remote brake
pipe section, the sample set for each new sample comprising the
last seven samples; and determine a maximum value of the sample
set.
25. A system in accordance with claim 24 further configured to:
compare the maximum value of the sample set to the reference
pressure; reset the reference pressure equal to the maximum value
if the maximum value is less than the reference pressure; and
retain the reference pressure if the maximum value is greater than
the reference pressure.
26. A system in accordance with claim 25 further configured to:
continue to sample the pressure, accumulate a sample set, determine
the maximum value, compare the maximum value, reset the reference
pressure, and retain the reference pressure until the brake pipe
pressure for said remote brake pipe section drops to a specified
level; compare a value of each sampled pressure to the brake pipe
reference pressure after each sampling; and determine whether an
undesired brake release has occurred in said remote locomotive
based on the comparison of each sampled pressure to said reference
pressure.
27. A system for filtering undesired fluctuations in brake pipe
pressure during brake application in a train, the train comprising
at least one of a lead locomotive, a remote locomotive, and a
railcar, said system comprising: at least one computer for
executing brake control functions of the train; and a brake pipe
that extends along a length of the train for supplying air for
brake operations, said brake pipe comprising at least one brake
pipe section such that each lead locomotive and remote locomotive
in the train comprises a respective brake pipe section, each said
brake pipe section comprising: a feed valve cutoff valve and relay
valve for controlling the flow of air into said respective brake
pipe section; a brake pipe flow sensor for sensing air flow into
the brake pipe; and a brake pipe pressure sensor for sensing
pressure in said respective brake pipe section, wherein said system
configured to initiate a feed valve cut-out for each said lead
locomotive feed valve and said remote locomotive feed valve,
measure an initial pressure in each said lead locomotive brake pipe
section, said remote brake pipe section, and set a reference
pressure for each said brake pipe section equal to the value of the
initial pressure of said respective brake pipe section.
28. A system in accordance with claim 27 further configured to:
sample the pressure, at a specified duty cycle, in each said lead
locomotive brake pipe section and said remote brake pipe section
during brake applications; accumulate a sample set for each said
brake pipe section, the sample set for each new sample comprising
the last seven samples; and determine a maximum value of each
sample set.
29. A system in accordance with claim 28 further configured to:
compare the maximum value for each sample set to the respective
brake pipe reference pressure; reset the respective reference
pressure for said respective brake pipe section equal to the
respective maximum value if the respective maximum value is less
than the respective brake pipe reference pressure; and retain the
respective reference pressure for said respective brake pipe
section if the respective maximum value is greater than the
respective brake pipe reference pressure.
30. A system in accordance with claim 29 further configured to:
continue to sample the pressure, accumulate the sample set,
determine the maximum value, compare the maximum value, reset the
reference pressure, and retain the reference pressure until the
brake application is released; compare a value of each sampled
pressure to the respective brake pipe reference pressure; and
determine whether an undesired brake release has occurred in the
respective lead locomotive and remote locomotive based on the
comparison of each sampled pressure to the respective brake pipe
reference pressure.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/259,030, filed Dec. 29, 2000.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to braking applications of
a distributed power train, and more particularly to facilitating
reducing delays in braking applications of later sections of the
train when communication has been lost between a remote locomotive
and a lead locomotive, and to facilitate reducing undesired brake
releases once a brake application has begun.
[0003] A distributed power train typically includes a lead
locomotive and one or more remote locomotives, and railcars,
comprehensively referred to as rolling stock. Each piece of rolling
stock has braking equipment including at least a section of brake
pipe, a brake control valve, reservoirs, and a brake cylinder. Each
lead and remote locomotive has braking equipment that includes at
least a main reservoir, a section of brake pipe, a feed valve, a
cutoff valve, a relay valve, a brake control valve, and a brake
cylinder. The brake pipe sections are connected to form a brake
pipe that extends the length of the train. When the feed valve of a
locomotive is "cut-in", the relay valve is enabled, and controls
the brake pipe by charging or increasing the brake pipe pressure to
release the train brakes, or exhausting the brake pipe pressure to
apply the train brakes. When the feed valve is "cut-out", the relay
valve is disabled and the control of the brake pipe is suspended
for that locomotive. At least some known railway braking equipment
does not have an accelerated emergency-braking feature wherein each
piece of rolling stock in the train exhausts air from the brake
pipe locally. Rather, for emergency braking situations, the entire
brake pipe must be exhausted through the locomotives. During
distributed power operations on trains that do not have the
accelerated emergency-braking feature, emergency braking is
accomplished by venting the brake pipe at both the lead and remote
locomotives. However, if communication is lost between the lead and
remote locomotives, then the remote locomotive will not receive the
emergency brake command and the brake pipe must be entirely vented
by the lead locomotive.
[0004] To further complicate such a situation, if the remote
locomotive maintains the feed valve in a "cut-in" position, the
braking equipment of the remote locomotive will attempt to increase
the brake pipe pressure, thus reversing the brake application being
applied from the lead locomotive. Also, if the remote locomotive
remains in traction, it will continue to push the front part of the
train. This situation can cause dangerously high "in-train" forces
to build within the train if the remote locomotive is not idled and
the feed valve is not "cut-out" quickly enough.
[0005] To facilitate minimizing such effects, at least some known
systems utilize a flow sensing feature that detects when a train
brake application has been made and idles the remote locomotive and
cuts-out the remote feed valve. The flow sensing features sense the
airflow in the brake pipe resulting from a brake application. If
the lead locomotive has communicated to the remote locomotive that
a brake application is to occur, then the remote locomotive will
follow the throttle and brake applications from the lead
locomotive. Conversely, if the lead locomotive has not communicated
to the remote locomotive that a brake application is to occur, then
upon sensing a change in air flow identifying an application of the
brakes, the remote locomotive attempts to communicate with the lead
locomotive to verify if the brake application is desired. If the
lead locomotive signals that the brake application is desired the
remote locomotive will follow the throttle and brake applications
from the lead locomotive. If the lead locomotive does not reply to
the remote locomotive communication check, then the remote
locomotive is set to idle and the feed valve is "cut-out", which
disables the relay valve and brake pipe charging/exhausting is
suspended.
[0006] During times of communication loss between the lead and
remote locomotives, the feature of verifying with the lead
locomotive that brake application is desired takes a number of
seconds to accomplish. During this time, the remote locomotive
continues in traction and supplies air into the brake pipe, thereby
minimizing the braking effect in the later sections of the train.
During emergency brake applications this delayed feed valve cut-out
and idling of the remote locomotive creates the undesirable
situation where the front part of the train has maximum braking,
the later parts of the train have minimum or no braking, and the
remote locomotive continues to push the front part of the train.
The net result is that the rear of the train runs into the front
part of the train causing high in-train forces and possible
derailment.
BRIEF DESCRIPTION OF THE INVENTION
[0007] In one aspect, a method is provided to facilitate reducing
delays in braking applications in a train using a system. The
system includes at least one computer for executing brake control
functions of the train and a brake pipe that extends along a length
of the train for supplying air for brake operations. The train
includes a lead locomotive, at least one remote locomotive, and at
least one railcar. The method includes sensing a change in airflow
in the brake pipe, determining whether the change in air flow is
desired, sensing brake pipe pressure; and filtering undesired
fluctuations in brake pipe pressure during brake applications based
on the determination of whether the change in airflow is
desired.
[0008] In another aspect, a system is provided to facilitate
reducing delays in braking applications in a train. The system
includes at least one computer for executing brake control
functions of the train and a brake pipe that extends along a length
of the train for supplying air for brake operations. The train
includes a lead locomotive, at least one remote locomotive, and at
least one railcar. The system is configured to sense a change in
airflow in said brake pipe, determine whether the change in air
flow is desired, sense brake pipe pressures; and filter undesired
fluctuations in brake pipe pressure during brake applications based
on the determination of whether the change in airflow is
desired.
[0009] In yet another aspect, a system is provided for filtering
undesired fluctuations in brake pipe pressure during brake
application in a train. The train includes at least one of a lead
locomotive, a remote locomotive, and a railcar. The system includes
at least one computer for executing brake control functions of the
train, and a brake pipe that extends along a length of the train
for supplying air for brake operations. The brake pipe includes at
least one brake pipe section such that each lead locomotive and
remote locomotive in the train includes a respective brake pipe
section. Each brake pipe section includes a feed valve cutoff valve
and relay valve for controlling the flow of air into the respective
brake pipe section, a brake pipe flow sensor for sensing air flow
into the brake pipe, and a brake pipe pressure sensor for sensing
pressure in the respective brake pipe section. The system is
configured to initiate a feed valve cut-out for each lead
locomotive feed valve and remote locomotive feed valve, measure an
initial pressure in each lead locomotive brake pipe section and
remote brake pipe section. The system is further configured to set
a reference pressure for each brake pipe section equal to the value
of the initial pressure of the respective brake pipe section.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is an exemplary schematic of the railcar section for
a system to facilitate reducing delays in braking applications and
reducing undesired brake releases in a train.
[0011] FIG. 2 is an exemplary schematic of the locomotive section
for a system to facilitate reducing delays in braking applications
and reducing undesired brake releases in a train.
[0012] FIG. 3 is a flow chart of an exemplary method utilizing the
system shown in FIGS. 1 and 2 to facilitate reducing undesired
brake releases during brake applications of a train.
DETAILED DESCRIPTION OF THE INVENTION
[0013] FIGS. 1 and 2 are exemplary schematics of a system 10 used
to facilitate reducing delays in braking applications within a
train (not shown) when communication has been lost between a remote
locomotive (not shown) and a lead locomotive (not shown).
Furthermore, system 10 facilitates reducing undesired brake
releases once a brake application has begun.
[0014] As used herein, the term "train" means one or more
locomotives and one or more railcars physically connected together,
with one locomotive designated as a lead locomotive and other
locomotives designated as remote locomotives.
[0015] Referring now to FIG. 1, system 10 rail car brake equipment
includes a control valve 70 for executing brake control functions
of the train and a brake pipe 18 that extends along a length of the
train. Brake pipe 18 includes a plurality of connected brake pipe
sections 22 and 24 for supplying and venting air during operation
of a brake cylinder 26. When the train brakes are released, air
pressure in brake pipe 18 increases to some defined release
pressure. Control valve 70 charges a reservoir 60 to the defined
release pressure and vents brake cylinder 26 pressure through an
exhaust 38. When the train brakes are applied, brake pipe 18
pressure drops. Control valve 70 measures the difference in brake
pipe 18 pressure and reservoir 60 pressure, and applies the
difference in pressure to brake cylinder 26. A greater drop in
brake pipe 18 pressure results in a greater difference in pressure
with reservoir 60, and a greater brake cylinder 26 pressure.
[0016] Referring now to FIG. 2, system 10 locomotive equipment
includes at least one computer 14 for executing brake control
functions of a train, and a brake pipe 18 that extends along a
length of the train. The brake pipe includes a plurality of
connected brake pipe sections 22 and 24 for supplying and venting
air during operation of brake cylinder 26 as discussed above
regarding system 10 railcar brake equipment. Each locomotive in the
train also includes a respective brake pipe section 22 including a
relay valve 75 that controls the flow of air in the respective
brake pipe section 22. Also, a main reservoir 65 supplies air
through an air flow sensor 35 to relay valve 75 during charging
(releasing of the brakes) of brake pipe 18. Air flow sensor 35
communicates flow pressure values to computer 14. In addition, each
brake pipe section 18 includes a brake pipe pressure sensor 34 for
sensing pressure in brake pipe section 18 and communicating
pressure values to computer 14. Furthermore, system 10 includes an
exhaust 38 that is connected to relay valve 75 for exhausting air
from brake pipe section 22. Additionally, system 10 includes a feed
valve cutoff valve 72 that supplies air to disable operation of
relay valve 75 and suspend release and application capabilities of
relay valve 75. Computer 14 includes a processor 46 for executing
all functions of computer 14, and an electronic storage device 50
for storing information, programs and data.
[0017] In one embodiment, system 10 includes one computer 14
located in each locomotive in the train. Each computer 14 controls
the operation of a respective feed valve cutoff valve 72 which
controls the operation of relay valve 75, and communicates with
sensors 34 and 35 of the respective locomotive in which it is
located. Additionally, each computer 14 coordinates communications
between the respective locomotive and all other locomotives in the
train. However, alternate embodiments are possible wherein, for
example, system 10 includes only one computer 14 located in the
lead locomotive, or system 10 includes one of a plurality of
computers 14 located in each locomotive.
[0018] When a train encounters an emergency braking situation, the
lead locomotive initiates an emergency brake application and the
brakes for the entire train are applied by venting brake pipe 18.
In railcar equipment without emergency propagation capabilities,
the emergency venting of brake pipe 18 occurs through both the lead
and remote locomotives. The lead locomotive sends an emergency
braking command to the remote locomotive notifying the remote
locomotive that an emergency brake application is desired. However,
if communications are lost between the lead locomotive and the
remote locomotive, the lead locomotive starts to vent brake pipe
18.
[0019] In one embodiment, sensors 34 and 35 monitor the air flow
and air pressure in brake pipe section 22. When an emergency
braking situation occurs and a remote locomotive has not received
an emergency braking command, the venting of brake pipe 18 through
the lead locomotive causes air to flow in brake pipe 18 and all
brake pipe sections 22, thereby causing all brakes in the train to
start to engage. Sensor 35 senses the flow in brake pipe section 22
and communicates the air flow to computer 14. Computer 14
identifies the flow as unexpected flow, and immediately cuts-out
feed valve cutoff valve 72 so that system 10 will not attempt to
fill brake pipe section 22 and release the brake application.
Furthermore, computer 14 initiates communication of a message from
the remote locomotive to the lead locomotive to verify whether the
brake application is desired.
[0020] After the verification message is sent by computer 14, the
lead locomotive signals whether or not the brake application is
desired. If the lead locomotive signals that the brake application
is desired, computer 14 cuts back in feed valve cutoff valve 72,
system 10 allows relay valve 75 to apply brakes as commanded by the
lead locomotive, and the remote locomotive remains in commanded
traction. Conversely, if the remote locomotive does not receive a
signal from the lead locomotive, then computer 14 continues to
cut-out feed valve 30 and idles the remote locomotive within one
second of detecting the unexpected air flow in brake pipe section
22.
[0021] Once a brake application is confirmed, sensor 34 continues
to monitor air pressure in brake pipe section 22. In one
embodiment, sensor 34 samples the air pressure at a specified duty
cycle and transmits each pressure measurement to computer 14.
Computer 14 establishes an initial brake pipe reference pressure
using the first pressure value transmitted by sensor 34 as the
brake application begins. Subsequently, sensor 34 continues to
transmit samples to computer 14 and computer 14 compares each
subsequent sample to the initial reference pressure. An increase in
pressure of a specified amount and for a specified duration
indicates a potential brake release. If a brake release is
undesired, but the monitored air pressure in brake pipe section 22
indicates that a release has occurred, the train is put into an
emergency state and brake pipe 18 is vented in its entirety.
Therefore, to reduce undesired brake releases due to fluctuation of
air pressure in brake pipe section 22, computer 14 filters out
undesired fluctuations using the pressure samples.
[0022] After the initial brake pipe reference pressure is
established, computer 14 accumulates a sample set consisting of the
next seven pressure samples. Computer 14 then determines a maximum
value of the sample set and compares the maximum value to an
initial reference pressure. If the maximum sample set value is
greater than the initial reference pressure value, the initial
reference pressure value remains unchanged and each subsequent
sample is compared to that value. If the maximum sample set value
is less than the initial reference pressure value, the reference
pressure value is reset to a filtered reference pressure of the
maximum sample set value and subsequent samplings are compared to
the filtered reference pressure. The next seven samples are
accumulated into a set, and the maximum value of the set is
compared to filtered reference pressure, such that the filtered
reference pressure value is left unchanged or is reset to the
maximum value of the latest sample set. The cycle continues until
the pressure in brake pipe section 22 drops to a specified low
point that is considered to be a full brake application.
[0023] If at any point during the brake application, sampled
pressures, when compared to the filtered reference pressure,
indicate an increase in pressure of the specified amount for the
specified duration, and a brake release is undesired, the train is
put into an emergency state and brake pipe 18 is entirely vented.
The method of reducing undesired brake releases described above is
not limited to use when a brake application has occurred with
communications lost between a remote locomotive and a lead
locomotive. In an alternate embodiment, the method for reducing
undesired brake releases is utilized for all brake applications,
regardless of whether communications have been lost between the
remote and lead locomotives.
[0024] FIG. 3 is a flow chart 100 illustrating an exemplary method
of utilizing system 10 (shown in FIG. 1) to facilitate reducing
undesired brake releases during brake applications of a train.
During a train braking application, a brake pipe sensor monitors
104 air pressure in a brake pipe section by sampling 106 the air
pressure at a specified duty cycle. The sensor then transmits 108
each pressure measurement to a computer. The computer establishes
110 an initial brake pipe reference pressure using the maximum
value of the last seven pressure samples transmitted by the sensor
as the brake application begins. Subsequently, the sensor continues
to transmit 112 samples to the computer and the computer compares
114 each subsequent sample to the initial reference pressure. An
increase in pressure of a specified amount and for a specified
duration indicates a potential brake release. If a brake release is
undesired, but the monitored air pressure in the brake pipe section
indicates that a release has occurred, the train is put into an
emergency state and the brake pipe is entirely vented. Therefore,
to reduce undesired brake releases due to fluctuation of air
pressure in the brake pipe section, the computer filters out
undesired fluctuations using the pressure samples.
[0025] After the initial brake pipe reference pressure is
established, the computer accumulates 116 a sample set for each new
sample consisting of the last seven pressure samples. The computer
then determines 118 a maximum value of the sample set and compares
120 the maximum value to the initial reference pressure. If the
maximum sample set value is greater than the initial reference
pressure value, the initial reference pressure value remains
unchanged 122 and each subsequent sample is compared to that value.
If the maximum sample set value is less than the initial reference
pressure value, the reference pressure value is reset 124 to a
filtered reference pressure of the maximum sample set value and
subsequent samplings are compared to the filtered reference
pressure. The next seven samples are accumulated 126 into a set,
the maximum value of the set is compared 128 to filtered reference
pressure, and the filtered reference pressure value is left
unchanged or is reset 130 to the maximum value of the latest sample
set. The cycle continues 132 until the brake application is
released.
[0026] While the invention has been described in terms of various
specific embodiments, those skilled in the art will recognize that
the invention can be practiced with modification within the spirit
and scope of the claims.
* * * * *