Abstract:
A control system which allows electro-pneumatic control of an equalizing reservoir with the capacity to create penalty applications in a purely pneumatic manner. A controller for the equalizing reservoir includes an electro-pneumatic source of pressure or atmosphere responsive to an electrical equalizing pressure control signal and a pilot valve selectively connecting the electro-pneumatic source or atmosphere to the equalizing reservoir in response to pressure in a pilot port of the first pilot valve. A magnetic valve is provided having a first input connected to a second source of pressure, a second input connected to atmosphere and an output connected to the pilot port of the first pilot valve. At least one penalty valve is connected to the pilot input of the first pilot valve and is responsive to a penalty signal to connect the pilot input to atmosphere. A fourth valve has a first input connected to the second input of the first pilot valve and an output connected to a third source of pressure lower than pressure in the equalizing reservoir prior to a penalty signal. The fourth valve connects its first input to its output in response to a penalty signal. A method of initializing the electro-pneumatic source of pressure or atmosphere responsive to an electrical equalizing pressure control signal.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
   The present system relates generally to brake control systems and more specifically to a controller for an equalizing reservoir of a rail brake system, which includes a brake pipe controlled by a relay valve in response to pressure in the equalizing reservoir. 
   Prior rail brake systems have had either fully-pneumatic control of the equalizing reservoir (ER) or electro-pneumatic control of the ER. On systems which use fully-pneumatic ER control, penalty brake applications were created by exhausting a previously pressurized penalty pipe. This caused a subsequent pneumatic exhaust of the ER and brake application. On systems which use electro-pneumatic ER control, penalty brake applications are signaled to the brake system by electrical signals. The ER is then reduced to apply the brakes via electro-pneumatic control. Prior brake systems including ER controllers are illustrated in U.S. Pat. Nos. 6,036,284 and 6,318,811. 
   To limit the penalty reduction of the equalizing reservoir, prior systems have used reduction limiting reservoirs. Penalty application valves connect the reduction limiting reservoir to the equalization reservoir for a penalty and cuts off the control from the brake valve. The pressure in the equalizing reservoir is reduced until the two reservoir stabilize. After termination of the penalty, control is transferred back to the brake valve and the reduction limiting reservoir is emptied. Two such systems are shown in U.S. Pat. Nos. 3,623,777 and 4,491,372 
   A control system which allows electro-pneumatic control of an equalizing reservoir with the capacity to create penalty applications in a purely pneumatic manner is described in U.S. Pat. No. 6,746,087. The controller for the equalizing reservoir includes an electro-pneumatic source of pressure or atmosphere responsive to an electrical equalizing pressure control signal and a pilot valve selectively connecting the electro-pneumatic source or atmosphere to the equalizing reservoir in response to pressure in a pilot port of the first pilot valve. A magnetic valve is provided having a first input connected to a second source of pressure, a second input connected to atmosphere and an output connected to the pilot port of the first pilot valve. At least one penalty valve is connected to the pilot input of the first pilot valve and is responsive to a penalty signal to connect the pilot input to atmosphere. The pilot valve and the penalty valve pneumatically produce a brake application regardless of the state of the magnetic valve or its controller. 
   The present control system allows electro-pneumatic control of ER but with the capacity to create penalty applications in a purely pneumatic manner and reduction limiting. A controller for an ER includes an electro-pneumatic source of pressure or atmosphere responsive to an electrical equalizing pressure control signal and a first pilot valve selectively connecting the electro-pneumatic source or atmosphere at a first input or a second input to the equalizing reservoir in response to pressure in a pilot port of the first pilot valve. A magnetic valve is provided having a first input connected to a second source of pressure, a second input connected to atmosphere and an output connected to the pilot port of the first pilot valve. At least one penalty valve is connected to the pilot input of the first pilot valve and is responsive to a penalty signal to connect the pilot input to atmosphere. A fourth valve has a first input connected to the second input of the first pilot valve and an output connected to a third source of pressure lower than pressure in the equalizing reservoir prior to a penalty signal. The fourth valve connects its first input to its output in response to a penalty signal. 
   A method is disclosed for controlling pressure for an equalizing reservoir of a rail brake system which includes a brake pipe controlled by a relay valve in response to pressure in the equalizing reservoir and which includes an electro-pneumatic source of pressure or atmosphere having a closed loop system responsive to an electrical equalizing pressure control signal. The method includes measuring pressure in the equalizing reservoir after a penalty reduction of reservoir pressure; initially setting the electrical equalizing pressure control signal to the measured equalizing reservoir pressure after a penalty; and subsequently the activating closed loop system of the electro-pneumatic source of pressure or atmosphere to control the pressure of the equalizing reservoir to the electrical equalizing pressure control signals. 
   These and other aspects of the present invention will become apparent from the following detailed description of the invention, when considered in conjunction with accompanying drawings. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a schematic of a controller for an equalizing reservoir of the prior art. 
       FIG. 2  is a schematic of a controller for an equalizing reservoir illustrating a first embodiment of the present invention. 
       FIG. 3  is a schematic of a controller for an equalizing reservoir illustrating a second embodiment of the present invention. 
       FIG. 4  is a schematic of a controller for an equalizing reservoir illustrating a third embodiment of the present invention. 
       FIG. 5  is a schematic of a control of the limiting magnetic valve of  FIGS. 3 and 4 . 
       FIG. 6  is a flow chart of the control of the equalizing reservoir after a penalty of the prior art. 
       FIG. 7  is a flow chart of the control of the equalizing reservoir after a penalty according to the present disclosure. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  is the equalizing portion of the controller for the equalizing reservoir of U.S. Pat. No. 6,746,087, which is incorporated herein by reference. Where possible the same numbers will be used for sake of clarity. The controller for the equalizing reservoir is only part of a train brake control system, as illustrated in the previously mentioned patents. This equalizing controller may be used with systems other than those illustrated in the aforementioned patents. 
   As shown in the figures, an equalizing reservoir (ER)  10  is connected to and controls a brake pipe relay  12  via line  11 . The brake pipe relay  12  controls a brake pipe (BP). Also, connected to the brake pipe relay  12  is exhaust (EX) and a supply or main reservoir (MR) via line  13 . As is well known, the brake pipe relay  12  receives a reference signal  11  from the ER  10  and produces an appropriate pressure in the brake pipe (BP) using exhaust (EX) and pressure from the main reservoir (MR) via line  13 . Reduction in the pressure in the ER  10  produces a reduction in the pressure in the brake pipe (BP), which reflects a brake application. An increase in the pressure in ER  10  creates an increase in the pressure in brake pipe (BP), which is a brake release signal. The brake pipe cut off and charging circuit have been deleted for sake of clarity. How this is accomplished is well-known, as illustrated in the above-mentioned patents. 
   The main reservoir (MR) is also connected via line  13  to an electro-pneumatic source of pressure or atmosphere  16 , which is responsive to an electrical equalizing pressure control signal. The electro-pneumatic source  16  may include an electro-pneumatic or magnetic apply valve and an electro-pneumatic or magnetic release valve connected together at a common output  17  are shown in U.S. Pat. No. 6,746,087. Even though a pair of valves may form the electro-pneumatic source of pressure or atmosphere  16 , a single valve may be used or any other electro-pneumatic control system to provide a desired equalizing reservoir pressure signal. The output  17  is connected to an equalizing reservoir transducer (ERT). 
   The output  17  is also provided as a first input to the equalizing reservoir pilot valve (PVER)  22 . The other input is from atmosphere or exhaust (EX) on line  45 . The output of the PVER  22  is provided on line  19  to the ER  10 . The pilot port or pilot line  23  of valve  22  is connected to an output  27  of an electro-pneumatic or magnetic valve  24 . A second pressure source at the input of  24  on line  21  is from the main reservoir (MR) and through a choke or restriction C 3 . The restriction C 3  prevents the charging of the pilot port  23  when the penalty valve connects the pilot port  23  to exhaust (EX) or atmosphere. 
   The equalizing magnetic valve (MVER)  24  is shown in its deactivated condition, wherein the pilot port  23  is connected to exhaust (EX). Upon activation, the source is connected to the pilot valve  22  to move it from its shown exhaust position to its control pressure position connecting its output  19  to line  17 . The control of the electro-pneumatic source  16  determines the pressure provided through the open pilot valve  22  to the ER  10 . These connections and operations are well known in the prior art, as shown in the previously discussed patents. 
   Also, connected to pilot port  23  of the PVER  22  are pneumatic penalty valve  26  and/or electric or electro-pneumatic penalty valve  28  via penalty pilot line  25 . Both of the valves  26  and  28  are responsive to a penalty input signal to connect their respective outputs to penalty pilot line  25  to exhaust (EX). This removes the pilot signal from pilot port  23  of the PVER  22  causing it to return to the shown position connecting its output  19  and the ER  10  to atmosphere or exhaust (EX). This causes the brake pipe relay  12  to reduce the brake pipe pressure causing a brake application. 
   The pressure value in the penalty pilot line  25  to pilot port  23  is monitored by a penalty pressure transducer (PT) via line  27 . This may be used in controlling the ER  10  using the electro-pneumatic source  16  and indicates that a penalty valve has been activated connecting the penalty pilot line  25  to exhaust (EX). 
   A controller  50  is provided. This controller provides all of the control signals to the various electro-pneumatic or magnetic valves and receives feedback from each of the transducers. Controller  50  is illustrated as a single block and may be the controller of the brake system, which may be a single controller or may be plural distributive controllers. Portions of the controller  50  may be on a module, which includes the controller for the ER  10  as illustrated in FIG. 9 of U.S. Pat. No. 6,036,284 with other portions of the controller  50  being part of a system controller. Controller  50  is also shown controlling the electro-pneumatic penalty valves. Again, this would generally be performed by the brake system controller versus a distributive controller portion of the ER  10 . 
   As illustrated in FIG. 2 of U.S. Pat. No. 6,746,087, the penalty pilot line  25  may be connected to the input  21  of the MVER magnetic valve  24  instead of its input. 
   The operation of the system in  FIG. 1  provides a pneumatic actuated braking in response to a penalty condition whether it is an electro-pneumatically or pneumatically sensed penalty. The controller  50  prevents a continuous exhaust of MR out of an open penalty valve. The controller can detect a penalty condition via PT and act to de-energize (close) MVER valve  24 , thereby preventing any further exhaust of air. This also prevents a continuous exhaust of air when the controller (and magnetic valve  24 ) are in a powered off condition. This would allow an unpowered locomotive to be hauled unmanned with an open foot valve, for instance. 
     FIGS. 2-4  show a modification to the equalizing reservoir system of  FIG. 1  to incorporate reduction limiting. While  FIG. 2  show the use of a reduction limiting reservoir and  FIG. 3  shows an additional reduction limiting magnetic valve,  FIG. 4  show a combination of both in series. 
   The line  45  of the first pilot valve (PVER)  22  is provided as a first input to a reduction limiting pilot valve (PVRL)  62 . The other input is line  63  which is from atmosphere or exhaust (EX). The output of the PVRL  62  is provided on line  61  to a reduction limiting reservoir (RLR)  60 . The pilot port or pilot line  65  of the PVRL  62  is connected to the pilot line  23  of the first pilot valve PVER  22 . 
   In response to a penalty input on line  25 , pilot line  65  is connected to exhaust. This removes the pilot signal of each the PVER  22  and the PVRL  62  causing each to be in the shown position. In the shown position, line  19  of the ER  10  is connected to line  45  from the PVER  22  to the input of the PVRL  62  and thus line  61  of RLR  60 . The pressure within ER  10  will reduce into the volume of RLR  60 . The pressure reduction within the ER  10  is proportionate to the volumetric size relationship of the ER  10  to the RLR  60 . This will cause ER  10  to reduce a prescribed amount due to a penalty and thus not fully to atmosphere, thereby causing a predetermined brake application instead of a full or maximum brake application. 
   As described in the prior art of  FIG. 1 , upon activation of the equalizing magnetic valve  24  and closure of the penalty valve  26 / 28 , source pressure is connected to pilot lines  23  and  65  via line  27 . The PVER  22  shall move from its shown penalty position to its control pressure position connecting its output  19  to line  17 . Upon connecting source pressure to pilot line  65 , the PVRL  62  shall change from its penalty position to connect its output line  61  to line  63  and exhaust (EX), thus depleting the pressure within the RLR  60  to restore full penalty reduction capability. 
   The use of a magnetic valve as the reduction limiting device is illustrated in  FIG. 3 . The output line  45  of the pilot valve (PVER)  22  is provided as a first input to a penalty limiting magnetic valve (MVSP)  64 . The other input is line  67  which is from atmosphere or exhaust (EX). The penalty valve  26 / 28  is responsive to a penalty input to connect line  23  to exhaust and thus remove the pilot signal to the PVER  22  causing a response to the shown position. In the shown position, line  19  of the ER  10  is connected to line  45  from the PVER  22  to the input of the MVSP  64  and thus line  67  to atmosphere or exhaust (EX). The pressure within ER  10  will reduce to cause a braking. 
   Upon activation of the magnetic valve (MVSP)  64  input line  45  is disconnected from line  67  to atmosphere or exhaust (EX). The pressure within ER  10  will cease to reduce and thus maintain the brake application attained as long as the pilot valve  22  remains in the position shown or penalty. 
   Subsequent de-activation of MVSP  64  will reconnect to line  45  to exhaust, thus further reducing ER  10  and allow a greater brake application. Subsequent activation will cease reduction and maintain the brake application attained. By the activation control of MVSP  64  during the purely override penalty operation of the system, the brake application step increase may be controlled, maintained or fully applied. 
   The activation and deactivation of the MVSP  64  could be single source or various other designs. A simple method could be the activation of a timing relay by a pressure sensor within the pilot line  23  that would support a single step delay of equalizing reservoir prior to full exhaust. Another method could be that of a controller, that may be intelligent, to control the steps either over time or sensor feedback control. 
   A combination of the reduction limiting devices or systems of  FIGS. 2 and 3  are shown in  FIG. 4 . The magnetic valve MVSP  64  is connected to line  45  between the pilot valve PVER  22  and the pilot valve PVRL  62 . This provides the current limiting features of the current limiting reservoir  60  with the stepped or staged reduction and safety features of the magnetic valve MVSP  64 . 
     FIG. 5  show the elements of a safety design through redundant controllers for the reduction limiting magnetic valve MSVP  64 . 
   The activation system includes two distinct, independent controllers  66  and  68 . The controllers are electronic and may be of solid state or microprocessor intelligent technologies. Significant are that these controllers are separate and independent with capable knowledge to control the activation of MVSP  64 . The controllers are arranged in series with the MVSP  64  in a manner that a failure of one would not prevent the other from deactivating the MVSP  64 . 
   As shown in  FIG. 5  the MVSP  64  is deactivated. The electric source for activation must first be allowed to pass through controller  66 , as determined by its input requirements through closure of its switch, which may be solid state control or relay contacts, to the MVSP  64 , through the activation circuit of the MVSP (coil) and allowed to pass through controller  68  to attain source to return and thus activate the MVSP  64 . Controller  68  like controller  66  determines by its distinct input requirements the closure of its switch, which may be solid state control or relay contacts. Similarly, the controllers in series may activate a single relay to control MVSP  64 . 
   High level of safety is achieved in that the MVSP  64  must be activated to prevent the application of braking. The controllers  66  and  68  are redundant, that is each must be in the activation mode to activate the MVSP  64 . Failure of one in activation is overridden by the other. There would be several arrangements that would enhance the safety of the circuitry as the series addition of independent locomotive safety devices, such as cab signal, positive train control and vigilant systems. All to prevent the activation of the circuitry and thus allow braking to apply to the full potential. 
   Recovery of the pressure in the pilot port  23  results in the pilot valve PVER  22  disconnecting the equalizing reservoir ER  10  from atmosphere and connecting it to the electro-pneumatic source of pressure  16 . When pressure in the ER is actively in the stage of reducing and when a penalty override terminates, an abruptly reconnect to the electro-pneumatic source  16  may cause an undesirable effect. The prior art options is to 1) stop the reduction from occurring any further or 2) delay the recovery of the pilot port pressure till full application of braking. Option 1 is not desirable as full application may not have been attained and removes the selection of adding more braking through the control of the electro-pneumatic source  16 . Option 2 is not desired as the time for assurance of full braking capability would be a restriction to the overall operating system or control of the locomotive. 
   The present design allows for the connection of ER  10  to the electro-pneumatic source  16  with no degradation to braking ability, expectation of the operator or inhibit to further application braking. The present design is applicable to any of the equalizing reservoir control system with an electro-pneumatic control including but limited to those illustrated in  FIGS. 1-4 . 
   In the prior art, the controller  50  has a responsibility in the recovery of a penalty application. As described above, recovery of a penalty requires the restoration of supply pressure to pilot line  23 . Supply source pressure is not available unless the controller  50  has activated the MVER  24  to connect source line  13  to pilot line  23 . The PPV or EPV  26 / 28  must be activated to disconnect the pilot line  23  from atmosphere or exhaust. Only then may the pilot line  23  be allowed to develop pressure and activate the PVER  22 . The activated PVER  22  disconnects exhaust or reduction limiting line  45  and connects the ER  10  line  19  to line  17  and thus the electro-pneumatic controller  16 . 
   As illustrated in  FIG. 6 , a determination is made at step  70  whether recovery is possible. If so the, controller  50  would delay activation of the MVER  24  through its logic to assure that the ER  10  has reduced sufficiently to assure a reliable application of braking. Prior to activation of MVER  24  at step  74 , the controller  50  disconnects each the supply and exhaust of the electro-pneumatic controller  16  from line  17  at step  72 . Thus on the activation of the PVER  22  due to the development of pressure within line  25 , the ER  10  would neither increase or decrease pressure, thereby maintaining the level of braking achieved. 
   The controller  50  would monitor the feedback level sensor PT and determine the activation state of the PVER  22  at step  76 . Once the activation was determined and on command of the operator to fully release braking at step  78 , then the controller  50  would allow the electro-pneumatic controller  20  to increase, maintain and control pressure within line  17  and thus ER  10  at steps  82  and  84 . 
   In the present system as illustrated in  FIG. 7 , the controller  50  still has the responsibility in the recovery of a penalty application. As described in the prior art, the controller  50  activates the MVER  24  at step  74 , disconnects each the supply and exhaust of the electro-pneumatic controller  16  at step  72 , and monitors the feedback level sensor PT to determine the activation state of the PVER  22  at step  76 . Next the system allows the electro-pneumatic controller  16  to maintain, decrease or control pressure within line  17  and thus ER  10  without the requirement of the operator to fully release braking as in step  78 . 
   The controller  50  monitors the feedback level sensor PT to determine the activation state of the PVER  22  at step  76 . The controller  50  determines whether the ER  10  is in connection via line  19  and PVER  22  to line  17  and thus to the electro-pneumatic controller  16 . If so, the electro-pneumatic controller  16  has an integrated feedback level sensor that the controller  50  determines the pressure on line  17  and thus the pressure within the ER  10  from the transfer ERT of the electro-pneumatic controller  16  at step  86 . The controller  50  then sends a target ER signal to the electro-pneumatic controller  16  equal to the feedback level sensor value at step  88 . However electro-pneumatic control  16  does not allow connections to source or exhaust to be made. This preconditions the closed loop control of the electro-pneumatic controller  16 . The controller  50  determines the desired braking request from the locomotive at step  82 , which includes the operator and other logical requirements as the continuance of the penalty brake due to recovery needs. The electro-pneumatic controller  16  closed loop control is actuated at step  84  to selecting connect to source and/or exhaust to line  17  to establishing full electro pneumatic control of braking. 
   This method provides a seamless transition from the override of ER control function back to operator control, fully under the requirements and rules of the standards well known in the industry. The safety of the override features are not compromised but enhanced as the disconnection of source and exhaust at the electro-pneumatic controller prevent the possibility of the undesired effects of pressure leakage. The operator is not confused by a difference in operation and is less likely to over react that could result in undesirable heavy braking effects. 
   Although the present invention has been described and illustrated in detail, it is to be clearly understood that this is done by way of illustration and example only and is not to be taken by way of limitation. The scope of the present invention is to be limited only by the terms of the appended claims.