Fluid-pressure and analogous brake systems – Multiple systems – Fluid pressure and electric
Reexamination Certificate
1999-12-30
2002-04-23
Graham, Matthew C. (Department: 3613)
Fluid-pressure and analogous brake systems
Multiple systems
Fluid pressure and electric
C303S015000, C303S057000, C303S063000
Reexamination Certificate
active
06375275
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to air brake systems for railroad trains and is particularly directed to detecting an overcharge or a separation in the brake pipe and automatically controlling the train locomotive until the condition is resolved.
BACKGROUND OF THE INVENTION
One of the most critical aspects of the operation of railroad vehicles, particularly freight trains, is the predictable and successful operation of the air brake system. The air brake system is subjected to a variety of dynamic effects, not only as a result of the controlled application and release of the brakes through changes in the brake pipe pressure, but also due to varying conditions encountered by the train.
FIG. 1
illustrates a typical prior art brake system employed by a railway freight train. The train brake system comprises a locomotive brake system located on a locomotive
100
and a set of car brake systems located on a set of railway cars illustrated by car
200
. The application and release of braking action is generally controlled by an engineman within a locomotive
100
. The locomotive
100
contains an air brake control system
102
, including a controllably pressurized brake pipe
101
. The pressurized brake pipe
101
is connected (via one of a series of cut-out valves
120
) to the train air line
201
. It is through the train air line
201
that air brake pressure is supplied to each of the cars
200
of the train. The brake control system
102
also includes an air supply input link
111
for supplying, under pressure, fluid (air) through which the brake pipe
101
and the train air line
201
are charged. Ultimately, the air brake control system
102
controls the operation of the pneumatically operated brake shoes
233
at each of the wheels
235
of the car
200
.
A flow measuring adapter
113
, and its associated charging rate gauge
115
, are connected to the air supply link
111
. The flow measuring adapter
113
and the charging rate gauge
115
measure and display the charging rate (as a differential pressure) of the brake control system
102
. The output terminal
116
of the flow measuring adapter
113
is connected to input port
121
of a relay valve
117
. A bi-directional port
122
of the relay valve
121
is coupled to the brake pipe
101
. The relay valve
117
further includes a port
123
that is coupled through an air pressure control link
103
to an equalizing reservoir
105
. The pressure control link
103
is also connected to a pressure control valve
107
through which the equalizing reservoir
105
is charged and discharged in the process of a brake operation. A port
124
of the relay valve
117
is controllably vented to the atmosphere as an exhaust port. Coupled with brake pipe
101
and air pressure control link
103
are respective pressure measuring and display devices
131
and
133
. The brake pipe gauge
131
measures the air pressure in the brake pipe
101
and the equalizing reservoir gauge
133
measures the pressure in the equalizing reservoir.
The components of the car air brake control system
102
, include a control valve
203
, having a port
221
that is coupled to the train airline
201
. Control valve
203
also includes a port
222
that is coupled to a pressure storage and reference reservoir
205
. Finally, the control valve
203
includes a port
223
coupled to the air brake cylinder
231
that controls the movement of the brake shoe
233
against the wheels
235
of the car
200
.
In operation, the cut out valve
120
, through which brake pipe
101
and successive segments of the train air line
201
are coupled in serial fluid communication, is assumed to be fully open, so that there will be a continuous brake pipe/air line fluid path between the locomotive
100
and all of the cars
200
of the train. The brake system is initially pressurized by the operation of pressure control unit
107
, which controls the air supply to line
103
so as to fully charge the equalizing reservoir
105
. The relay valve
117
is then operated to couple port
121
with port
122
so that air is supplied there through to the brake pipe
101
and thereby to the train air line
201
, to charge the brake pipe/air fluid line path
101
/
201
to the predetermined charging pressure. This pressure (typically 72 psi. on UIC trains) is established by the pressure of the equalizing reservoir
105
within the locomotive
100
. The pressure within the brake pipe
101
and the train air line
201
is determined to have reached the correct pressure, as established by the pressure in the equalizing reservoir
105
, when the pressure at port
122
(connected to the brake pipe
101
) matches the pressure at port
123
(connected to the equalizing reservoir
105
).
Through control valves
203
in each of the cars
200
, the pressure storage and reference reservoirs
205
are filly charged, to thereby establish a reference pressure for maximum withdrawal of the piston of each air brake cylinder
231
and thereby complete release of the brakes
233
for each of the cars
200
.
When the engineman desires to apply brakes to the wheels of the train cars
200
, he operates pressure control unit
107
, typically via a handle-operated control valve, which is coupled to the air pressure control link
103
. Operation of the pressure control valve
107
causes a partial venting of air pressure control link
103
and thereby a reduction in the pressure within the equalizing reservoir
105
. This reduction in pressure in the equalizing reservoir
105
is sensed by the relay valve
117
at port
123
. In turn, this causes the bi-directional port
122
to be coupled to the exhaust port
124
and thereby exhaust the brake pipe
101
to the atmosphere, until the pressure within the brake pipe
101
equals the pressure of equalizing reservoir
105
.
As the pressure in the brake pipe
101
and therefore within the train air line
201
drops, the control valves
203
in each of the cars
200
sense the pressure reduction in the train air line
201
by comparison to the pressure in the pressure storage and reference reservoir
205
. This causes a corresponding increase in the pressure applied to the brake cylinders
231
from port
223
, resulting in an application of the brake shoes
233
against the wheels
235
in proportion to the sensed pressure reduction in the train air line
201
. Further pressure reductions in the equalizing reservoir
105
by the engineman produce corresponding pressure reductions in the train air line
201
and, thereby, additional braking effort by the brake shoes
233
in each of the cars
200
. In summary, the intended operation of the brake system in the cars
200
and specifically the braking effort applied in each of the cars
200
, is proportional to the reduction in pressure in the equalizing reservoir
105
within the locomotive
100
.
When the engineman desires to release the train car brakes, he operates pressure control unit
107
to effectuate a recharging of the air brake control system
102
. This is accomplished by bringing the pressure within the equalizing reservoir
105
back to its fully charged state as described above. With equalizing reservoir
105
recharged, there is again a pressure differential (but opposite in sign to the previous pressure drop in the pressure line
103
) between the ports
122
and
123
of the relay valve
117
. This increase in pressure is sensed by the control valves
203
in each of the cars
200
so as to cause the brake shoes
233
to be released by the action of the brake cylinder
231
.
During normal operation, the application and release of the brakes is controlled in accordance with the above described sequence of events. However, there may be circumstances dictated either by action taken by the engineman or by other unpredictable events, which create the potential for unsafe operation of the braking system. One of these conditions relates to the standards and operation of the brake system on European trains having a UIC (Union Internationale de Chemins Fer) brake system.
Delaruelle Dale H.
Deno Milton C.
Hines Carl
Johnson Don K.
Smith, Jr. Eugene A.
GE-Harris Railway Electronics, L.L.C.
Graham Matthew C.
Hayden Scott R.
Holland & Knight LLP
Rowold Carl A.
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