Title of Invention

"REGULATINE VALVE DEVICE AND RAILROAD TRAIN BRAKE PIPE PRESSURE CONTROL SYSTEM HAVING SAID REGULATING VALVE DEVICE"

Abstract A brake pipe pressure control system for a railroad train including a regulating valve device under control of a microprocessor wherein the regulating valve device is housed in the existing end-of-train device and effects service and emergency reductions of brake pipe pressure from the rear end of the train in correspondence with service and emergency reductions initiated at the locomotive.
Full Text The present invention relates to a regulating valve device and railroad train brake pipe pressure control system having said regulating valve device.
The invention relates to a pneumatic brake pipe pressure regulating valve device and more particularly to such a valve device that exhausts the pressure in the brake pipe of a railroad train at a location remote from the train locomotive consistent with a brake valve regulated service reduction of brake pipe pressure at the train locomotive.
There is currently an ongoing effort underway to develop electro-pneumatic brakes for railroad freight trains. It is generally acknowledged that such electro-pneumatic brake control can enhance train operation by achieving faster brake response, more equalized car retardation, and uniform braking effort throughout a long train of cars. This implies that ail of the cars or at least a majority of the cars in a train be appropriately equipped for electro-pneumatic braking, in which case direct brake cylinder pressure control is envisioned. With the exception of certain unit trains, however, it cannot be reasonably expected that any such majority of cars would be immediately implemented with the required electro-pneumatic equipment. Accordingly, indirect brake cylinder pressure control is contemplated, in which the train brake pipe pressure is controlled at one or several remote cars throughout the train to accelerate reductions of brake pipe pressure in order to obtain faster brake response.
regulating valve device in the event of an electrical malfunction.
It is a final object of the invention to provide a brake pipe pressure regulating valve, as in the foregoing, that is suitably sized for installation in end-of-train units.
Briefly, these objectives are carried out through a regulating valve device that is connected to the train brake pipe at the end-of-train unit and operates to exhaust the brake pipe pressure at either a service or an emergency rate in accordance with a radio transmitted command signal from the locomotive. Until the commanded brake pipe pressure is reached, a pressure differential exists across the regulating valve control piston, which operates an exhaust valve to reduce the brake pipe pressure to a value corresponding to the command signal. The pressure differential during a service application is only sufficient to displace the exhaust valve a limited distance in which a metering action through a variable flow orifice occurs to regulate the exhaust of brake pipe pressure so as to not produce an emergency rate. During an emergency application, the higher control' piston pressure differential displaces the exhaust valve a distance sufficient to suddenly fully open the exhaust valve and thereby provide an emergency rate of reduction of brake pipe pressure.
Brief Description of the Drawings
These and other objects and advantages of the invention will become apparent from the following more detailed description when taken in conjunction with the accompanying drawings in which:
Fig. 1 is a schematic view showing a railroad train comprising a plurality of freight cars headed by a locomotive having radio communication with an end-of-train unit on the last car of the train;
Fig. 2 is a block diagram of a microprocessor based indirect brake cylinder pressure control system adapted for end-of-train service.
Fig. 3 is a graph showing how the brake pipe pressure at the end of the train transitions to a reduced pressure under control of the end-of-train unit in accordance with the present invention.
Fig. 4 is a diagrammatic view showing a first embodiment of an electrically operated pneumatic regulating valve for carrying out the service and emergency reduction of brake pipe pressure in accordance with the indirect brake cylinder pressure control system of Fig. 2;
Fig. 5 is a diagrammatic view of a second embodiment of the brake pipe pressure regulating valve employed in the indirect brake cylinder pressure control system of Fig. 2 employing a pneumatic charging value to achieve fail-safe electro-pneumatic operation;
Fig. 6 is a diagrammatic view cf a third embodiment of the invention similar to the Fig. 5 embodiment in which an additional emergency and release assuring solenoid valve
Accordingly the present invention provides a regulating valve device for reducing the fluid pressure in a railroad train brake pipe at a location remote from the train locomotive comprising:
a) an exhaust passage open to atmosphere;
b) a supply passage to which said brake pipe is connected;
c) a control passage;
d) a bore having said exhaust passage and said supply passage opening
thereinto;
e) an annular valve seat in said bore between said exhaust passage and said
supply passage;
f) an exhaust valve member having a protrusion in cooperation with said
bore to provide a variable flow orifice therebetween;
g) a valve seal element on said exhaust valve member adjacent said valve
seat;
h) a spring acting on said exhaust valve member in a direction to effect
engagement of said valve seal element with said valve seat;
i) a control piston having a first chamber on one side thereof to which said
control passage is connected and a second chamber on the opposite side
thereof to which said supply passage is connected;
j) an actuating stem between said control piston and said exhaust valve
member, said control piston being operative in response to a pressure
differential between said first and second chambers to effect disengagement
of said valve seal element from said valve seat via said actuating stem
without displacing said protrusion from said bore provided said pressure
differential occurs as a result of a fluid pressure change in either one of said
first and second chambers relative to the other of said first and second chambers at a service rate that is less than a predetermined emergency rate.
The present invention also provides a railroad train brake pipe pressure control system having the above-mentioned regulating valve device, said brake extending from the locomotive to a remote location in said train, a brake pipe pressure control system comprising:
a) receiving means at said remote location for receiving a brake pipe
pressure command signal;
b) said regulating valve device to which said brake pipe is connected at said
remote location;
c) transducer means for providing a feedback signal corresponding to the
brake pipe pressure effective at said regulating valve device;
d) electro-pneumatic means for controlling fluid pressure communication
between said brake pipe and said regulating valve device and between said
regulating valve device and atmosphere; and
e) control means for operating said electro-pneumatic means to establish
said fluid pressure communication between said regulating valve device and
atmosphere in response to said command signal being less than said
feedback signal, said regulating valve device comprising:
(i) an exhaust passage open to atmosphere;
(ii) a supply passage to which said brake pipe is connected;
(iii) a first control passage to which said brake pipe is connected;
(iv) a bore having said exhaust passage and said supply passage opening thereinto;
(v) an annular valve seat in said bore between said exhaust passage and said supply passage;
(vi) an exhaust valve member having a valve seal element adjacent said valve seat;
(vii) a spring acting on said exhaust valve member in a direction to effect engagement of said valve element with said valve seat;
(viii) a control piston having first and second chambers formed on opposite sides thereof to which said first control passage is connected and a second chamber formed on the opposite side thereof to which said supply passage is connected; and
(ix) an actuating stem between said control piston and said exhaust valve member, said control piston being operative in response to a pressure differential between said first and second chambers to effect disengagement of said valve element from said valve seat via said actuating stem against the force of said spring when said pressure differential occurs as a result of a fluid pressure change in either one of said first and second chambers relative to the other of said first and second chambers.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
These and other objects and advantages of the invention will become apparent from the following more detailed description when taken in conjunction with the accompanying drawings in which:
Fig. 1 is a schematic view showing a railroad train comprising a plurality of freight cars headed by a locomotive having radio communication with an end-of-train unit on the last car of the train;
Fig. 2 is a block diagram of a microprocessor based indirect brake cylinder pressure control system adapted for end-of-train service.
Fig. 3 is a graph showing how the brake pipe pressure at the end of the train transitions to a reduced pressure under control of the end-of-train unit in accordance with the present invention.
Fig. 4 is a diagrammatic view showing a first embodiment of an electrically operated pneumatic regulating valve for carrying out the service and emergency reduction of brake pipe pressure in accordance with the indirect brake cylinder pressure control system of Fig. 2;
Fig. 5 is a diagrammatic view of a second embodiment of the brake pipe pressure regulating valve employed in the indirect brake cylinder pressure control system of Fig. 2 employing a pneumatic charging value to achieve fail-safe electro-pneumatic operation;
Fig. 6 is a diagrammatic view of a third embodiment of the invention similar to the Fiq. 5 embodiment in which an additional emergency and release assuring solenoid valve
piston member 40 in its de-activated position. Piston member 40 is pressure balanced during such charging of the brake pipe so that control spring 56 is effective to maintain exhaust valve 42 closed.
Also, exhaust solenoid valve E when de-energized is in its normally closed position in which the pressure supplied to piping network 19 via supply solenoid valve S is cut-off from atmosphere.
At each car CN including the last car C^, as shown in Fig. 2, control valve device CV operates in response to the increasing brake pipe pressure to charge auxiliary reservoir AR and emergency reservoir ER to the operating pressure of brake pipe BP, while concurrently venting the car brake cylinder device BC, this function of control valve CV being commonly known as "release and charging".
When it is desired to make a service brake application following charging of brake pipe BP, the locomotive brake valve device (not shown) is set. in a position to achieve a brake pipe pressure reduction corresponding to the degree of brake application desired. This reduction of brake pipe pressure constitutes a pneumatic signal that propagates through the train from front to rear via brake pipe BP.
Concurrently, a service brake command signal is transmitted via radio from the locomotive to the end-of-train unit EOT corresponding to the reduced locomotive brake pipe pressure. Microprocessor MPU operates in response to a difference between the transmitted command signal at input 9 and a feedback signal from transducer T at input 8 to energize and thus open exhaust solenoid valve
E, while the normally open condition of the de-energized supply solenoid valve S remains unchanged. Appropriately sized chokes 60, 62 are provided at the respective inlets 14, 18 of solenoid supply and exhaust valve S, E, the flow capacity of these chokes 60, 62 at the prevailing pressure differentials thereacross being such that less air is supplied to piping network 19 than is exhausted. This initiates a regulating phase of operation of regulating valve device RV, in which the control pressure in stability chamber 58 and effective in control chamber 57 is reduced at a predetermined service rate until the reduced control pressure corresponds to the target pressure in accordance with the command signal transmitted to input 9 of microprocessor MPU.
At the commencement of this reduction of control pressure effective in chamber 57, the pressure in chamber 55 remains substantially constant due to the normal delay in the propagation of the brake pipe pressure reduction from the front to the rear of the train. Accordingly, a downward acting force differential is created across piston member 40 to actuate piston member 40 and thereby cause stem 45 to engage exhaust valve 42 and disengage valve element 44 from seat 46 against the force of spring 56. Exhaust valve 42 is thus opened and brake pipe pressure is exhausted at the last car C^ via branch pipe 10, passage 52, the open exhaust valve 44/46, bore 41, exhaust passage 50 and port EX. In this manner, a brake pipe pressure reduction is initiated at the end-of-train unit on the last car of the train, concurrently with the reduction initiated
at the locomotive. The amount of deflection of piston member 40, as controlled by the pick-up rate of control spring 56 in response to the actuating pressure differential across piston member 40, determines the relationship between tapered protrusion 54 and bore 41, and thus the exhaust orifice area via which brake pipe pressure and also the pressure effective in chamber 55 exhausts. If the rate of pressure reduction in chamber 55 is different than the predetermined rate of reduction of control pressure effective in chamber 57, the actuating pressure differential across piston member 40 will change accordingly, thereby allowing spring 56 to move exhaust valve 42 slightly in the appropriate direction to increase or decrease the exhaust orifice area and thereby adjust the exhaust of brake pipe pressure by reason of the relationship between tapered protrusion 54 and bore 41. It is also noteworthy that some brake pipe air will be exhausted via supply valve S and exhaust valve E in establishing the control pressure in chamber 57, in addition to the brake pipe air exhausted via valve 42. It will be appreciated, therefore, that piston member 40 is self-regulated such that in conjunction with the brake pipe pressure exhaust via exhaust solenoid valve E, exhaust valve 42 finds a position in which the rate of brake pipe pressure reduction effective in chamber 55 corresponds to the predetermined rate of pressure reduction established in control chamber 57 by solenoid valves E and 5 and chokes 62 and 60. This predetermined rate cf control pressure reduction represents a service rate at which the brake pipe
pressure reduction via exhaust valve 42 is thus limited, so long as protrusion 54 is not displaced from bore 41. When the reducing pressure in control chamber 57 and 58 reaches the commanded target pressure, as determined by microprocessor MPU in accordance with the feedback signal received from transducer T (Fig. 2), supply solenoid valve S is energized to cut-off further supply of brake pipe pressure to piping network 19 and exhaust solenoid valve E is de-energized to cut-off further exhaust of control pressure from piping network 19.
This terminates the initial phase of relay valve operation and initiates a stabilizing phase of control. As the brake pipe pressure continues to be exhausted via open exhaust valve 42, the corresponding pressure reduction in chamber 55 gradually reduces the actuating differential across piston member 40, allowing spring 56 to return valve element 44 to its seat 46 and thereby halt the reduction of brake pipe pressure via exhaust valve 42.
In that brake pipe pressure is temporarily greatest near the middle of the train, as represented by curve A in Fig. 3, during the pressure transition from the train operating pressure represented by curve B to a reduced pressure represented by curve C, it will be appreciated that the air in the brake pipe will flow from the middle towards the front and rear and gradually stabilize at the natural pressure gradient of the reduced brake pipe pressure.
During the regulating phase of regulating valve operation, premature closure of exhaust valve 42 results in
this pressure equalization flow causing an increase in the brake pipe pressure towards the rear of the train. The resultant pressure rise at the rear of the train causes an increase in pressure at relay valve chamber 55, reestablishing a pressure differential with the fixed pressure in control chamber 57 to force piston member 40 in a downward direction. Accordingly, exhaust valve 42 is reopened to exhaust more brake pipe pressure via exhaust passage 50 and exhaust port EX until the reduced brake pipe pressure restores a pressure balance on piston member 40 to allow spring 56 to again close exhaust valve 42. During this stabilizing phase of relay valve operation, the brake pipe pressure may be periodically reduced by self-regulating action until the pressure gradient along the brake pipe is substantially equalized at the commanded target pressure without any further operation of either one of the supply and exhaust solenoid valves. More typically, this self-regulating action in accomplished by reason of the exhaust valve 42 gradually pinching off as the brake pipe pressure is effectively reduced in the middle of the train and less and less air flows to the last car to be exhausted. The exhaust orifice is thus adjusted to permit the exhaust to exactly match the amount of air flowing to the valve from the mid-train brake pipe, thereby keeping the pressure consistent.
It may be found necessary, however, to very briefly open the exhaust solenoid valve E during this stabilizing period in the event a transient temperature increase should cause the trapped control pressure in chamber 57 to
increase inadvertently. In thus reducing the brake pipe pressure at the end-of-train unit EOT in conjunction with a brake pipe reduction at the locomotive or head end of the train during service braking, the control valve devices CV on cars toward the rear of the train respond more quickly to apply the car brakes so that more rapid and more uniform braking throughout the train is achieved.
If a further service reduction of brake pipe pressure is called for at the locomotive, microprocessor MPU is again commanded to establish a new target pressure by initiating another cycle of operation of relay valve RV via solenoid valves E and S, as explained.
When an emergency brake application is desired, microprocessor MPU receives the appropriate radio signal from the locomotive and energizes supply solenoid valve S, as well as exhaust solenoid valve E. In its energized condition, as shown in the solenoid valve operating schedule, solenoid valve S is closed to cut-off inlet 14 from outlet 16, while exhaust valve E is opened to connect its inlet 18 to outlet 22. Thus, while exhaust valve E vents piping network 19, as in the case of a service application, supply valve S is prevented from supplying any air to supplement the lost air in piping network 19, and therefore the control pressure reduction in chamber 57 occurs at a rate that exceeds the predetermined reduction rate during service, i.e., an emergency rate. This emergency reduction in control chamber 57 is encouraged by the fact that choke 59 is sized to limit the reduction of pressure in stability chamber 58 to a service rate, thus
effectively limiting the volumetric capacity of control pressure to that of chamber 57. The resultant reduction of control pressure in chamber 57 thus quickly exceeds the counteracting pressure reduction in chamber 55, which as previously explained, is limited to a maximum service rate in accordance with the relationship between protrusion 54 and bore 41. Accordingly, the pressure differential created across piston member 40 is sufficient to deflect exhaust valve 42 against the force of spring 56 sufficiently to displace protrusion 54 from bore 41 and thereby allow brake pipe pressure to escape to atmosphere substantially unrestricted. This sudden rapid reduction of brake pipe pressure at the end-of-train unit EOT initiates an emergency brake application at the rear of the train in conjunction with the emergency application initiated at the locomotive or head end of the train. The car control valves CV respond to this emergency reduction of brake pipe pressure to propagate the emergency wave forward from the end-of-train unit, as during a service reduction of brake pipe pressure, in order to hasten the emergency response of the control valve devices CV on cars CN situated toward the rear of the train.
In so controlling regulating valve device RV through solenoid operated supply and exhaust valves, as explained in the foregoing, it is desirable to have the solenoid valves de-energized during the 'release and charging" function, in order to minimize the consumption of battery power. Also, as explained, the supply solenoid valve must assume an open position during charging.
In the event of a power failure or malfunction of microprocessor MPU, that de-energizes supply solenoid valve S, it will thus automatically assume its open position. Should such an event occur during the stabilizing phase of a service brake application, supply valve S would be open instead of closed and thus cause the control pressure in chamber 57 to inadvertently increase and consequently cause closure of brake pipe exhaust valve 42 prematurely. The continued flow of brake pipe pressure from mid-train could then increase BP pressure at the rear and cause an undesired brake release.
In order to overcome this potential problem, an alternate regulating valve device RV is provided, which, as shown in the embodiment of Fig. 5, employs a pneumatically operated charging or supply valve PS in parallel with solenoid supply valve S, and a backflow check valve 90. This alternate regulating valve device RV is otherwise the same as the regulating valve device of Fig. 3.
The pneumatically operated charging valve PS comprises a supply valve 70 in which a check valve 72 is biased by a spring 74 in a direction away from an annular valve seat 76 and a diaphragm operated piston 78 having an actuating stem 80 arranged to move check valve 72 in a direction toward engagement with seat 76. A passage 82 is connected between chamber 55 and the inner area of valve seat 76, and another passage 94 is connected between chamber 57 and the area outside the periphery of valve seat 76. An exhaust passage 84 is connected between bore 41 and an actuating chamber 86 formed on one side of piston 78. This actuating chamber 86
is connected to atmosphere via a branch 88 of exhaust passage 84. Backflow check valve 90 is seated by a relatively light bias spring 92 to close exhaust passage 88 when the exhaust pressure in chamber 86 falls below approximately 4-5 psi. A bleed choke 95 is associated with check valve 90 to dissipate the final pressure trapped in actuating chamber 86 when check valve 90 is closed. Outlet 22 of exhaust solenoid valve E is connected by a back pressure pipe 96 to exhaust port EX of exhaust passage 50. During "release and charging", brake pipe pressure is connected to chamber 55 via branch pipe 10 and passage 53, and concurrently charges chamber 57 via the open supply check valve 70 independently of solenoid supply valve S. This allows the supply valve S to be normally closed. Both of the solenoid supply and exhaust valves are de-energized by microprocessor MPU during this charging period to conserve power, as shown in the following solenoid valve operating schedule.

(Table Removed)
As previously explained, exhaust valve 42 is also closed under the influence of spring 42, by reason of piston member 40 being pressure balanced. Choke 59 conducts air from control chamber 57 to stability chamber 58.
When a service brake application is called for, microprocessor CPU responds to the commanded brake pipe target signal transmitted from the locomotive L to energize solenoid operated supply valve S and exhaust valve E, each of which assumes its open position, as indicated in the solenoid valve operating schedule. As previously explained, the control pressure in chambers 57 and 58 is released at a predetermined rate in accordance with the initial phase of operation of regulating valve device RV. In the present embodiment, the exhaust pressure at outlet 22 of exhaust solenoid valve E is connected to actuating chamber 86 via back pressure pipe 96, exhaust port EX, exhaust passage 50 and exhaust passage 84. This pressure builds up in chamber 86 to the opening pressure of check valve 90, which is sufficient to actuate piston 78 and thereby effect closure of supply valve 70 by engagement of valve element 72 with seat 76. This assures that a pressure reduction occurs in control chamber 57 in response to operation of solenoid valves S and E to initiate the aforementioned initial phase of relay valve operation, during which piston member 40 is actuated to open exhaust valve 42 and accordingly vent brake pipe BP until the brake pipe pressure is reduced to a value corresponding to the commanded target pressure.
When the control pressure effective in chamber 57 and monitored by transducer T corresponds to the commanded target pressure, both of the solenoid valves E and S are de-energized by microprocessor CPU. Being closed in their de-energized state, in accordance with this second
embodiment of the invention, as shown in the solenoid valve operating schedule, the solenoid valves trap the control pressure effective in chamber 57 as a reference value, against which further brake pipe pressure adjustments are made as the brake pipe pressure gradient settles out. It will now be appreciated that in the event a malfunction should render either one or both of the solenoid valves de-energized during this stabilizing phase of the brake pipe pressure reduction, the position of the solenoid valve(s) and thus the control pressure trapped in chamber 57 will remain unchanged and thus have no adverse affect on the brake pipe pressure reduction. That is, the charging valve will not re-open prematurely because it will be held closed by the pressure in chamber 86 until the mid-train brake pipe pressure is reduced to the natural gradient.
Another embodiment of the invention is shown in Fig. 6, in which the electro-pneumatic interface unit EP comprises, in addition to supply and exhaust solenoid valves S and E, a solenoid-operated, spring-returned, normally closed emergency valve EM and release assuring valve RA.
Regulating valve device RV in this embodiment is similar to the version shown in the embodiment of Fig. 5, being modified to the extent necessary to interface with the respective solenoid valves EM, RA, as follows. Exhaust passage 84 is fitted with a choke 98 at a location intermediate actuating chamber 86 and branch passage 88; an alternate exhaust passage 100 having a port 102 is connected to actuating chamber 86; and stability chamber 58
is provided with a port 104. Piping network 19 associated with the supply and exhaust solenoid valves S and E is connected to port 104 instead of control port 20, as in the previous embodiments. Control port 20 is connected to an inlet 106 of emergency solenoid valve EM, which has an outlet 108 connected to exhaust port EX via a pipe 96. Outlet 22 of solenoid exhaust valve E is connected by a pipe 112 to port 102 of alternate exhaust passage 100 instead of pipe 96, as in the embodiment of Fig. 5. Release assuring valve RA has an output 114 that is vented to atmosphere and an inlet 116 that is connected to pipe 112. The respective emergency and release assuring solenoid valves are connected to microprocessor MPU via wires 118 and 120.
In providing a separate emergency solenoid valve EM, the capacity requirement of supply and exhaust solenoid valves S and E is considerably reduced, which permits smaller valves to be employed to achieve finer increments of brake pipe pressure reductions for more accurate brake control. The availability of space within existing end-of-train units severely limits the size of volume 58 and makes the use of smaller sized solenoid valves an important requirement. Employing a combination of chokes 60, 62 associated with supply and exhaust valves S and E makes it possible to achieve the desired control of pressure in such a small volume as stability chamber 58 using standard sized choke fittings. Only if the capacity of volume 58 were substantially greater, absent the space restriction imposed by existing end-of-train units, for example, would it be
practical to eliminate supply valve S and its choke 60, with exhaust solenoid valve E controlling the service reduction of control pressure in chamber 58 via choke 62 and emergency solenoid EM controlling the emergency reduction of pressure in chamber 58 via choke 110.
Given the limited capacity of volume 58, the operation of regulating valve device RV in the embodiment of Fig. 5 will be explained employing both the supply and exhaust solenoid valves S and E, in conjunction with emergency solenoid valve EM and release assuring solenoid valve RA. The solenoid valves are all de-energized during "release and charging", and are thus in a closed state, as shown in the following solenoid valve operating schedule.

(Table Removed)
During the charging of brake pipe BP, air is connected to the underside of exhaust valve 42 via branch pipe 10, supply port 30 and passage 52, and concurrently to chamber 55 via branch passage 53, From chamber 55, air is conducted to control chamber 57 on the opposite side of piston member 40 via passage 82, open charging valve 70 and passage 94. Stability chamber 58 is charged from chamber 57 via choke 59. Under this cressure balanced condition of
piston member 40, exhaust valve 42 is held closed by spring 56.
When a service brake application is called for, microprocessor MPU energizes solenoid supply valve S and solenoid exhaust valve E. Due to the relative sizes of chokes 60, 62 a predetermined rate of reduction of pressure in stability volume 58 takes place, the air being vented via piping network 19, solenoid exhaust valve outlet 22, pipe 112, auxiliary exhaust passage 100, actuating chamber 86, choke 98, passage 84, backflow check valve 90 and exhaust passage 88. Being normally seated, however, backflow check valve 90 interrupts such venting until approximately 3-4 psi pressure develops in chamber 86, thereby effecting closure of charging valve 70. The pressure effective in control chamber 57 is also vented via choke 59, which is sized relative to choke 62 so as to vent at the same predetermined rate as the stability chamber pressure. With closure of charging valve 70, pressure in chamber 55 is thus maintained at brake pipe pressure, while the pressure in control chamber 57 is being reduced, thereby establishing a pressure differential therebetween in response to which piston member 40 is actuated to in turn unseat exhaust valve element 44 from seat 46. This establishes the initial phase of relay valve operation during which brake pipe pressure is exhausted via open exhaust valve 42 at a rate corresponding to the predetermined rate of the control pressure reduction.
When the pressure in control chamber 57 is reduced to the target pressure, as determined by microprocessor MPU,
in accordance with the command signal transmitted from the locomotive and the control pressure feedback signal from transducer T, the solenoid supply and exhaust valves are de-energized to trap the control pressure effective in chamber 57 and stability chamber 58. This terminates the initial phase of control and initiates a stabilization phase during which increasing brake pipe pressure at the end-of-train unit EOT, due to equalization of the brake pipe gradient, gradually establishes a pressure differential across piston member 40 sufficient to open exhaust valve 42 and accordingly exhaust brake pipe pressure to the fixed target value established by the control pressure effective in control chamber 57, until the higher mid-train brake pipe pressure is reduced and brake pipe pressure at the rear of the train stabilizes at the commanded target pressure.
A further reduction of brake pipe pressure at the eriS-of-train unit EOT may be made at any time during either the regulating phase or stabilizing phase of regulating valve operation, by commanding a reduced target pressure, in which case the above explained cycle of operation is repeated.
In the event a brake release Ls desired, the supply and exhaust, solenoid valves are de-energized and the regulating valve device RV is controlled accordingly to accommodate a pressure increase under control of the locomotive via brake pipe 3P, as explained relative to •"release and charging'.
If a brake release is desired during the stabilization phase of relay valve operation, i.e., prior to the brake pipe pressure gradient settling out, microprocessor MPU operates to momentarily (approx. 5-10 sec.) energize release assuring valve RA, the other solenoid valves bexng de-energized, as noted in the solenoid valve operating schedule. In its energized state, release assuring valve RA is open, connecting the holding pressure in chamber 86 to atmosphere via alternate exhaust passage 100, port 102, and pipe 112. Spring 76 is thus effective to disengage valve element 72 from seat 76 and thereby open charging valve 70 to allow the opposing pressures in chambers 55 and 57 to equalize. This, in turn, allows spring 56 to close exhaust valve 42 so that no exhaust of brake pipe pressure can occur during such re-charge of brake pipe pressure. In this manner an increase in brake pipe pressure and thus a brake release is assured. Without providing for such equalization of pressure between chambers 55 and 57, the increasing brake pipe pressure effective in chamber 55 in response to the desired brake release would re-enforce the existing pressure differential across piston member 40 and possibly cause the exhaust valve 42 to be held open. The resultant exhaust of brake pipe pressure at the end-cf-train unit EOT would accordingly counteract the brake pipe increase at the locomotive and could prevent a complete brake release from occurring, particularly on the cars situated near the rear of the train.
Another embodiment of the invention is shown in ?ig. which differs from the Fig. 4 embodiment in that
electro-pneumatic interface unit EP comprises, in addition to supply and exhaust solenoid valves S and E, a solenoid-operated, spring-returned, normally closed emergency valve EM, and a solenoid-operated, spring-returned, normally open charging valve CH. As explained relative to the embodiment of the invention of Fig. 6, it is desirable from the standpoint of space limitations to keep stability chamber 58 as small as possible, thus giving rise to a separate emergency solenoid valve EM, in order to permit relatively low capacity supply and exhaust solenoid valves S and E to be employed consistent with the low volumetric capacity of chamber 58. By utilizing a solenoid operated charging valve, this Fig. 7 embodiment differs from the Fig. 6 version in that it permits elimination of the pneumatic charging valve PS, yet still avoids the problem discussed in the Fig. 4 version relative to a loss-of-power malfunction that de-energizes the supply solenoid valve S during the stabilization phase of relay valve operation.
As shown in the following solenoid valve operating schedule, all of the solenoid valves are de-energized during "release and charging" in order to conserve power.

(Table Removed)
During the charging of brake pipe BP, air is connected to the underside of exhaust valve 42 via branch pipe 10,
supply port 30 and passage 52, and to chamber 55 on the upper side of piston member 40 via passage 53. Also from branch pipe 10, brake pipe air is connected to control chamber 57 at the underside of piston member 40 via open solenoid chcirging valve CH and a pipe 120 that is connected to control port 20. Stability chamber 58 is charged from control chamber 57 via choke 59.
When a service brake application is called for, microprocessor MPU energizes supply, exhaust and charging valves S, E and CH. As previously explained, the resultant supply and exhaust of air at the respective supply and exhaust valves is regulated by chokes 60 and 62 so that the resultant pressure in piping network 19 is reduced at a predetermined rate. Such an arrangement makes it feasible to obtain a service rate of reduction in stability chamber 58 and control chamber 57, while limiting the volumetric capacity thereof in accordance with the space available within existing end-of-train units EOT. Concurrently, charging valve CH is closed to terminate charging of control chamber 57 during such service reduction of control chamber pressure, as explained.
The resultant pressure differential developed across piston member 40 deflects the piston member to open exhaust valve 42 and thereby vent brake pipe BP via branch pipe 10, passage 52, open exhaust valve 42, passage 52 and exhaust port EX. The brake pipe pressure is thus reduced at the last car C3L in conjunction with a reduction at the locomotive. Control spring 56 in conjunction with the variable orifice area of exhaust valve 42 regulates the
rate of brake pipe pressure reduction so as to not exceed the predetermined rate established at control chamber 57 during this initial phase of relay valve operation.
When the target brake pipe control pressure called for has been attained, solenoid exhaust valve E is switched by microprocessor MPU to its de-energized, normally-closed state to terminate the control pressure reduction in chamber 57. This terminates the initial phase and initiates a stabilizing phase of relay valve operation, during which the other solenoid valves S, CH and EM are de-energized and the brake pipe pressure gradient flow is exhausted gradually by the self-regulating action of regulating valve RA until the gradient is stabilized.
A further reduction of brake pipe pressure at the end-of-train unit EOT may be made at any time during either the initial phase or stabilizing phase of regulating valve operation, by commanding a reduced target pressure in which case the above-explained cycle of operation is repeated.
In both of the embodiments of Figs. 6 and 7, an emergency rate of reduction of brake pipe pressure is achieved at the end-of-train unit EOT when microprocessor MPU energizes emergency solenoid valve EM, as indicated in the respective solenoid valve operating schedules, in accordance with transmission of an emergency command from the locomotive. In its energized condition emergency solenoid valve EM is open. In the Fig. 6 embodiment, control chamber pressure is thus exhausted via regulating valve control pert 20, emergency valve inlet 106 and outlet 108, pipe 96, regulating valve exhaust port EX, exhaust
passages 50 and 84 and branch passage 88. In the Fig. 7 version, control chamber pressure is exhausted directly at emergency valve outlet 108. In either case, the exhaust of control pressure in chamber 57 is substantially unrestricted, thus creating a pressure differential across piston member 40 sufficient to deflect exhaust valve 42 enough to displace tapered protrusion 54 from bore 48. Brake pipe pressure is thus exhausted substantially unrestricted past exhaust valve seat 46. In the Fig. 6 embodiment, the exhausting brake pipe pressure is vented to atmosphere via exhaust passage 84, backflow check valve 90 and branch passage 88. In the Fig. 7 version, brake pipe pressure is vented directly to atmosphere via exhaust passage 50 and exhaust port EX.
It will be understood that in providing a separate emergency valve EM in the embodiment of Figs. 6 and 7, smaller capacity supply and exhaust valves S, E may be employed. Moreover, separate charging valve CH makes supply valve S expendable when space limitation permits the volume of stability chamber 58 to be such that the exhaust valve choks 62 can produce a service rate of reduction of pressure in control chamber 57. Where this volume is restricted to less than approximately 6.0 cu. in., however, the exhaust of pressure via choke 62 must be counteracted to some degree by supplying brake pipe pressure to chamber 57 via choke 60, in order to limit the rate of reduction of control pressure in chamber 57 to a service rate.
Separate charging valve CH in the Fig. 7 embodiment further eliminates the need for a pneumatic charging or
supply valve PS, as employed in the Figs. 5 and 6 embodiments, irrespective of the size of stability chamber
58.






WE CLAIM:
1. A regulating valve device for reducing the fluid pressure in a railroad train brake pipe at a location remote from the train locomotive comprising:
a) an exhaust passage open to atmosphere;
b) a supply passage to which said brake pipe is connected;
c) a control passage;
d) a bore having said exhaust passage and said supply passage opening
thereinto;
e) an annular valve seat in said bore between said exhaust passage and
said supply passage;
f) an exhaust valve member having a protrusion in cooperation with said
bore to provide a variable flow orifice therebetween;
g) a valve seal element on said.exhaust valve member adjacent said valve
seat;
h) a spring acting on said exhaust valve member in a direction to effect
engagement of said valve seal element with said valve seat;
i) a control piston having a first chamber on one side thereof to which
said control passage is connected and a second chamber on the opposite
side thereof to which said supply passage is connected;
j) an actuating stem between said control piston and said exhaust valve
member, said control piston being operative in response to a pressure
differential between said first and second chambers to effect
disengagement of said valve seal element from said valve seat via said
actuating stem without displacing said protrusion from said bore provided said pressure differential occurs as a result of a fluid pressure change in either one of said first and second chambers relative to the other of said first and second chambers at a service rate that is less than a predetermined emergency rate.
2. A regulating valve device as claimed in claim 1, wherein said
protrusion of said exhaust valve member has a rectilinear taper.
3. A regulating valve device as claimed in claim 1, wherein said
protrusion of said exhaust valve member is conical in shape.
4. A regulating valve device as claimed in claim 1, wherein said
protrusion of said exhaust valve member is displaced from said bore
when said pressure differential occurs as a result of said fluid pressure
change in either one of said first and second chambers relative to the
other of said first and second chambers exceeding said service rate.
5. A regulating valve device as claimed in claim 1, wherein said first
chamber is connected to a stability chamber; by a connecting passage
between said stability chamber and said first chamber.
6. A regulating valve device as claimed in claim 1, wherein a charging
valve means is provided for Controlling fluid pressure communication
between said first and second chambers.
7. A regulating valve device as claimed in claim 6, wherein said
charging valve means consists of:
a) a normally open supply valve via which fluid pressure is conducted
from said second chamber to said first chamber;
b) an actuating piston operably engaged with said supply valve;
c) an actuating chamber formed on one side of said actuating piston,
said actuating chamber being connected to said exhaust passage; and
d) check valve means in said exhaust passage for establishing a pre
determined back pressure in said actuating chamber when said valve
seal on said exhaust valve member is disengaged from said valve seat to
thereby effect closure of said normally open supply valve.

8. A regulating valve device as claimed in claim 7, wherein said check
valve means is in parallel with choke for dissipating fluid pressure in
said actuating chamber when- said valve seal element of said exhaust
valve member is engaged with said valve seat.
9. A railroad train brake pipe pressure control system having a
regulating valve device as claimed in any of the preceding claims, said
brake extending from the locomotive to a remote location in said train, a
brake pipe pressure control system comprising:

a) receiving means at said remote location for receiving a brake pipe
pressure command signal;
b) said regulating valve device.to which said brake pipe is connected at
said remote location;
c) transducer means for providing a feedback signal corresponding to the
brake pipe pressure effective at said regulating valve device;
d) electro-pneumatic means for controlling fluid pressure communication
between said brake pipe and said regulating valve device and between
said regulating valve device and atmosphere; and
e) control means for operating said electro-pneumatic means to establish
said fluid pressure communication between said regulating valve device
and atmosphere in response to said command signal being less than said
feedback signal, said regulating valve device comprising:
(i) an exhaust passage open to atmosphere;
(ii) a supply passage to which said brake pipe is connected;
(iii) a first control passage to which said brake pipe is connected;
(iv) a bore having said exhaust passage and said supply passage opening thereinto;
(v) an annular valve seat in said bore between said exhaust passage and said supply passage;
(vi) an exhaust valve member having a valve seal element adjacent said valve seat;
(vii) a spring acting on said exhaust valve member in a direction to effect engagement of said valve element with said valve seat;
(viii) a control piston having first and second chambers formed on opposite sides thereof to which said first control passage is connected and a second chamber formed'on the opposite side thereof to which said supply passage is connected; and
(ix) an actuating stem between said control piston and said exhaust valve member, said control piston being operative in response to a pressure differential between said first and second chambers to effect disengagement of said valve element from said valve seat via said actuating stem against the force of said spring when said pressure differential occurs as a result of a fluid pressure change in either one of said first and second chambers relative to the other of said first and second chambers.
10. A brake pipe pressure control system as claimed in claim 9, wherein a) said exhaust valve member is provided with a protrusion on said exhaust valve member disposed within said bore and in cooperation therewith to provide a variable flow orifice therebetween; and
b) said valve seal element being disengageable from said valve seat without displacing said protrusion from said bore, whereby said fluid pressure change in either one bf said first and second chambers relative to the other of said first and second chambers is limited to a service rate that is less than a predetermined emergency rate.
11. A brake pipe pressure control system as claimed in claim 10,
wherein said protrusion has a rectilinear taper.
12. A brake pipe pressure control system as claimed in claim 10,
wherein said protrusion is conical in shape.
13. A brake pipe pressure control system as claimed in claim 10,
wherein said electro-pneumatic means comprises:
a) a solenoid-operated supply valve having an inlet connected to said
brake pipe and an outlet connected to said first control passage;
b) a solenoid-operated exhaust valve having an inlet connected to the
outlet of said supply valve and an outlet connected to atmosphere; and
c) first and second chokes respectively at the inlets of said supply and
exhaust valves, the flow capacity of said first choke and second choke
providing said reduction of fluid pressure in said first chamber at said
service rate in accordance with fluid pressure communication being
established between the inlet and outlet of each said supply and exhaust
valve.
14. A brake pipe pressure control system as claimed in claim 10,
wherein said regulating valve device is provided with charging valve
means for providing fluid pressure communication between said first and
second chambers.
15. A brake pipe pressure control system as claimed in claim 14,
wherein said charging valve means consists of:
a) a supply valve member;
b) a spring acting on said supply valve member in an opening direction;
c) a fluid pressure operated piston member acting on said supply valve
member in a closure direction opposite said opening direction; and
d) an actuating chamber in which said piston member is operatively
disposed, said exhaust passage opening into said actuating chamber.
16. A brake pipe pressure control system as claimed in claim 15,
wherein the outlet of said solenoid-operated exhaust valve is connected
to said exhaust passage.
17. A brake pipe pressure control system as recited in claim 16,
wherein said regulating valve device has:

a) backflow check valve means in said first exhaust passage; and
b) a branch passage connected between said actuating chamber and said
exhaust passage upstream of said backflow check valve means.
18. A brake pipe pressure control system as claimed in claim 17,
wherein said regulating valve device is provided with a third choke in
parallel with said backflow check valve means.
19. A brake pipe pressure control system as claimed in claim 18,
wherein said regulating valve device has an actuating passage connected
to said actuating chamber in parallel with said branch passage.
20. A brake pipe pressure control system as recited in claim 19,
wherein said electro-pneumatic means has a solenoid-operated release
assuring valve having an inlet connected to said actuating passage and
an outlet connected to atmosphere.
21. A brake pipe pressure control system as claimed in claim 20,
wherein said electro-pneumatic means is provided with said solenoid-
operated exhaust valve having the outlet thereof connected to said
actuating passage.
22. A brake pipe pressure control system as claimed in claim 21,
wherein said regulating valve device is provided with:

a) a stability chamber;
b) a connecting passage between said first chamber and said stability
chamber; and
c) a second control passage connected to said stability chamber.
23. A brake pipe pressure control system as claimed in claim 22,
wherein said electro-pneumatic means has a solenoid operated
emergency valve having an inlet connected to said first control passage
and an outlet connected to said exhaust passage.
24. A brake pipe pressure control system as claimed in claim 23,
wherein said regulating valve device has a fourth choke in said
connecting passage, said stability chamber having a volume of
approximately 65 cu. in.
25. A brake pipe pressure 'control system as claimed in claim 10,
wherein:
a) said regulating valve device is provided with:
(i) a stability chamber;
(ii) a second control passage connected to said stability chamber;
(iii) a connecting passage between said first chamber and said stability
chamber; and
b) said electro-pneumatic means has:
(i) a solenoid-operated supply valve having an inlet connected to said brake pipe and an outlet connected to said second control passage; and
(ii) a solenoid operated exhaust valve having an inlet connected to the outlet of said supply valve and an outlet connected to atmosphere; and
(iii) a solenoid operated charging valve having an inlet connected to said brake pipe and an outlet connected to said first control passage.
26. A brake pipe pressure control system as claimed in claim 24,
wherein:
a) said electro-pneumatic means has a solenoid-operated emergency
valve having an inlet connected to said first control passage and an
outlet connected to atmosphere; and
b) said regulating valve device has a third choke in said connecting
passage.

27. A regulating valve device for reducing the fluid pressure in a
railroad train brake pipe at a location remote from the train locomotive
substantially as hereinbefore described with reference to and as
illustrated in the accompanying drawings.
28. A railroad train brake pipe pressure control system substantially
as hereinbefore described with reference to and as illustrated in the
accompanying drawings.

Documents:


Patent Number 195057
Indian Patent Application Number 514/DEL/1996
PG Journal Number 52/2004
Publication Date 25-Dec-2004
Grant Date 17-Mar-2006
Date of Filing 12-Mar-1996
Name of Patentee WESTINGHOUSE AIR BRAKE COMPANY
Applicant Address AIR BRAKE AVENUE,WILMERDING,PENNSYLVANIA 15148,U.S.A
Inventors:
# Inventor's Name Inventor's Address
1 JAMES EDWARD HART 163 AUTUMN DRIVE,TRAFFORD,PENNSYLVANIA 15085,U.S.A
PCT International Classification Number B60T 11/26
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 08/562,961 1995-11-27 U.S.A.