Abstract:
A system and method for maintaining an airflow path to a turbocharger system on a locomotive operating at high altitude and in a low ambient temperature environment, is provided and includes generating an ambient air stream flow into the turbocharger system to create a compressed air stream flow having a compressed air stream temperature, wherein the ambient air stream flow includes an ambient air stream flow temperature, processing the compressed air stream to create an intercooler air stream having an intercooler air stream temperature, wherein the compressed air stream temperature is greater than the intercooler air stream temperature, directing at least a portion of at least one of the compressed air stream and the intercooler air stream toward a controllable re-circulation device, wherein the controllable re-circulation device is communicated with at least one of the compressed air stream flow and the ambient air stream flow, operating the controllable re-circulation device to combine the at least a portion of at least one of the compressed air stream and the intercooler air stream with at least one of the compressed air stream flow and the ambient air stream flow to increase at least one of the compressed air stream temperature and the ambient air stream temperature to a predetermined level.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims priority from U.S. Provisional Patent Application No. 60/590,495 filed Jul. 23, 2004, the contents of which are hereby incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to an internal combustion engine for a locomotive and, more particularly, to the recirculation of air to reduce the adverse effects of ambient air temperature changes on the performance of the engine.  
       BACKGROUND OF THE INVENTION  
       [0003]     Locomotives operated at high altitudes and in the far northern and southern regions of the globe are subject to severe environmental conditions which may have an adverse affect on the locomotive, including low atmospheric pressure, cold temperatures, and blowing and drifting snow.  
         [0004]     One problem involves blockage of the filters and/or ducts. It is known that snow may be drawn into the air inlet ducts of a locomotive and may accumulate in sufficient quantities to obstruct the passage of air through the ducts. Thus, it is not uncommon for snow to accumulate on air filters disposed in the air inlet pathway of the locomotive. Such accumulations of snow may act to reduce the power output of the engine and/or may cause the engine to cease from operating completely. One way to solve this problem involves providing summer/winter doors which function to connect the air inlet duct with a source of warm air so that the cold ambient air is mixed with relatively warmer air prior to passing through the final air filters. In this case, these doors allow if the temperature of the inlet air mixture can be maintained above the freezing point, any snow /or ice that may develop or be deposited on the filters and/or ductwork will melt rather than accumulating and restricting the intake airflow. When warm air is needed to prevent the buildup of snow/ice, the summer/winter doors are opened making warm air from the engine compartment available allowing the radiant and convection heat from the engine to warm the air near the filters and/or ductwork.  
         [0005]     Another problem involves the control of cylinder pressure to prevent the de-rating of the Gross Horse Power (GHP) on cold days. This is because relatively large compression-ignition engines, such as those used for locomotives, are usually operated at a full load with peak cylinder pressure (P p ), close to but not exceeding a maximum structurally allowable cylinder pressure value (P max ). As the ambient temperature drops below a nominal operating temperature (assuming ambient pressure (P a ) remaining unchanged), the peak cylinder pressure increases and may exceed the maximum structurally allowable cylinder pressure value. This is undesirable because it increases the engine component stress and loading.  
         [0006]     Another problem involves the surge margin (or engine stability limit) under cold ambient conditions and a high Manifold Air Temperature (MAT). Under these conditions the engine operating point as plotted on a turbocharger compressor performance map, moves toward an area of unstable operation called the surge line. This is often made worse at high altitudes.  
       SUMMARY OF THE INVENTION  
       [0007]     A locomotive turbocharger system for a locomotive engine subject to operation at high altitude and low ambient temperatures is provided and includes an air filtering device having an air filter inlet communicated with an air filter outlet via a filtering portion, the air filtering device being configured such that the filtering portion receives an ambient air stream having an ambient air stream temperature via the air filter inlet, generates a filtered air stream and discharges the filtered air stream via the air filter outlet, a compressor device having a compressor inlet communicated with a compressor outlet via a compressor portion, the compressor device being configured such that the compressor portion receives the filtered air stream via the compressor inlet, generates a compressed air stream having a compressed air stream temperature higher than the ambient air temperature and discharges the compressed air, an intercooler device having an intercooler inlet communicated with an intercooler outlet via a cooling portion, the intercooler device being configured such that the cooling portion receives compressed air stream via the intercooler inlet, generates an intercooler air stream having an intercooler air stream temperature lower than the compressed air stream temperature and discharges the intercooler air stream via the intercooler outlet wherein a first portion of at least one of the compressed air and the intercooler air is directed to the engine for use in engine combustion and a re-circulation valve in flow communication with the air filter inlet, the re-circulation valve being configured to receive a second portion of at least one of the compressed air and the intercooler air, wherein when the re-circulation valve is open for re-circulation, the re-circulation valve directs the second portion of at least one of the compressed air and the intercooler air into the ambient air stream such that the second portion of at least one of the compressed air and the intercooler air is combined with the ambient air stream to increase the temperature of the air flowing into the air filter  
         [0008]     A method for maintaining an airflow path to a turbocharger system on a locomotive operating at high altitude and in a low ambient temperature environment is provided and includes generating an ambient air stream flow into the turbocharger system to create a compressed air stream flow having a compressed air stream temperature, wherein the ambient air stream flow includes an ambient air stream flow temperature, processing the compressed air stream to create an intercooler air stream having an intercooler air stream temperature, wherein the compressed air stream temperature is greater than the intercooler air stream temperature, directing at least a portion of at least one of the compressed air stream and the intercooler air stream toward a controllable re-circulation device, wherein the controllable re-circulation device is in flow communication with at least one of the compressed air stream flow and the ambient air stream flow and operating the controllable re-circulation device to combine the at least a portion of at least one of the compressed air stream and the intercooler air stream with at least one of the compressed air stream flow and the ambient air stream flow to increase at least one of the compressed air stream temperature and the ambient air stream temperature to a predetermined level.  
         [0009]     A method for controlling operating characteristics of a locomotive engine having a turbocharger system relative to a surge operation of the turbocharger, wherein the locomotive engine is subject to operation at high altitude and low ambient temperatures, is provided and including directing an ambient air stream flow having an ambient air stream flow temperature into the turbocharger system to create a compressed air stream flow having a compressed air stream temperature higher than the ambient air stream temperature, directing a first portion of the compressed air to an intercooler device to create an intercooler air stream having an intercooler air stream temperature lower than the compressed air stream temperature, directing a second portion of at least one of the compressed air and the intercooler air toward a controllable re-circulation valve, wherein the controllable re-circulation valve is in flow communication with at least one of the compressed air stream flow and the ambient air stream flow and opening the re-circulation valve to combine the second portion of at least one of the compressed air and the intercooler air with at least one of the compressed air stream flow and the ambient air stream flow to reduce the discharge pressure of the compressed air from the turbocharger to change the operating characteristics of the engine and turbocharger so as to avoid surge operation of the turbocharger. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0010]     The foregoing and other features and advantages of the present invention will be more fully understood from the following detailed description of illustrative embodiments, taken in conjunction with the accompanying drawings in which like elements are numbered alike in the several Figures:  
         [0011]      FIG. 1A  is a schematic block diagram of a locomotive turbocharger system, in accordance with an exemplary embodiment;  
         [0012]      FIG. 1B  is a schematic block diagram of a first alternative embodiment of the locomotive turbocharger system of  FIG. 1 ;  
         [0013]      FIG. 2  is a schematic block diagram of a second alternative embodiment of the locomotive turbocharger system of  FIG. 1 ;  
         [0014]      FIG. 3  is a graph representing the ideal operating characteristics of the locomotive turbocharger system of  FIG. 1 ;  
         [0015]      FIG. 4  is a graph representing one embodiment of operating characteristics of the locomotive turbocharger system of  FIG. 1  at sea level;  
         [0016]      FIG. 5  is a graph representing an additional embodiment of operating characteristics of the locomotive turbocharger system of  FIG. 1  at altitude; and  
         [0017]      FIG. 6  is a block diagram illustrating a method for controlling the operating point of a locomotive engine operating at high altitude and in low ambient temperatures. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     Referring to  FIG. 1A , a schematic block diagram representing a first embodiment of a locomotive turbocharger system  100  is shown and includes a turbocharger re-circulation valve  102  having a valve actuation device  103 , an air filter box  104 , a turbocharger compressor portion  106 , a main intercooler device  108  and a locomotive engine  110 , wherein locomotive engine  110  includes an intake manifold  112  and an exhaust manifold  114 . Air filter box  104  includes an air inlet  116  and an air outlet  118 , turbocharger compressor portion  106  includes a turbocharger compressor inlet  120 , a turbocharger compressor outlet  122 , a turbocharger turbine exhaust inlet  124  and a turbocharger turbine exhaust outlet  126 . Main intercooler device  108  includes a main intercooler inlet  128  and a main intercooler outlet  130 . Intake manifold  112  includes an intake inlet  132  and an intake outlet  134  and exhaust manifold  114  includes an exhaust inlet  136  and an exhaust outlet  138 . In this embodiment, the main intercooler outlet  130  is in flow communication with the turbocharger re-circulation valve  102  to direct a cooled compressed air back into air filter box  104 .  
         [0019]     Referring to  FIG. 1B , a schematic block diagram representing a second embodiment of a locomotive turbocharger system  100  is shown and includes a turbocharger re-circulation valve  102  having a valve actuation device  103 , an air filter box  104 , a turbocharger compressor portion  106 , a main intercooler device  108  and a locomotive engine  110 , wherein locomotive engine  110  includes an intake manifold  112  and an exhaust manifold  114 . Air filter box  104  includes an air inlet  116  and an air outlet  118 , turbocharger compressor portion  106  includes a turbocharger compressor inlet  120 , a turbocharger compressor outlet  122 , a turbocharger turbine exhaust inlet  124  and a turbocharger turbine exhaust outlet  126 . Main intercooler device  108  includes a main intercooler inlet  128  and a main intercooler outlet  130 . Intake manifold  112  includes an intake inlet  132  and an intake outlet  134  and exhaust manifold  114  includes an exhaust inlet  136  and an exhaust outlet  138 . In contrast to  FIG. 1A , in this embodiment, the turbocharger compressor outlet  122  is in flow communication with the turbocharger re-circulation valve  102  to direct a compressed air back into air filter box  104 .  
         [0020]     It should be appreciated that, as shown in  FIG. 2 , an additional embodiment of locomotive turbocharger system  100  is shown and includes an optional intercooler device  140  having an optional intercooler inlet  142  and an optional intercooler outlet  144  may be included, as required. This may be utilized to satisfy new emission standards that require the air temperature of the air stream going into the intake manifold to be approximately equal to 100° Fahrenheit. It should also be appreciated that one or both of main intercooler device  108  and/or optional intercooler device  140  may be any type of intercooler device suitable to the desired end purpose, such as a water based intercooler device and/or an air to air intercooler device, and/or any combination thereof.  
         [0021]     Referring back to  FIG. 1A , locomotive turbocharger system  100  operates as follows. As the locomotive turbocharger system  100  is operated, ambient air is drawn into air filter box  104  via air inlet  116 , as represented by arrow  146 . Air filter box  104  filters this air and discharges the filtered air out of air outlet  118  and into turbocharger compressor portion  106  via turbocharger compressor inlet  120 , as represented by arrow  148 . Turbocharger compressor portion  106  compresses the filtered air and discharges the compressed air out of turbocharger compressor outlet  122  and into main intercooler device  108  via main intercooler inlet  128 , as represented by arrow  150 . Prior to being introduced into main intercooler device  108 , the compressed air typically reaches temperatures of approximately 400° Fahrenheit. This air is cooled by main intercooler device  108  and discharged via main intercooler outlet  130 . At this point, the temperature of the air stream coming out of main intercooler outlet  130  is approximately 200° Fahrenheit.  
         [0022]     As can be seen, one portion of this discharged air stream is directed toward the locomotive engine  110  and the remaining portion of the discharged air stream is directed toward valve actuation device  103 . The portion of this air stream directed toward engine  110  is directed into intake manifold  112  via intake inlet  132 , as represented by arrow  152 , and out of intake manifold  112  and into locomotive engine  110 . As the locomotive engine  110  operates, this air stream is used to help create combustion after which the resultant is exhausted out of locomotive engine  110  and into exhaust manifold  114  via exhaust inlet  136 . Exhaust manifold  114  then discharges this exhaust out of exhaust outlet  138  and into turbocharger turbine exhaust inlet  124 , as represented by arrow  154 . Turbocharger turbine portion  107  then discharges this exhaust via turbocharger turbine exhaust outlet  126 , as represented by arrow  158 .  
         [0023]     The portion of the air stream discharged from main intercooler device  108  directed toward valve actuation device  103  is directed into the air flow of the ambient air being drawn into air filter box  104  via air inlet  116 , as represented by arrow  156 . This causes the cold ambient air and the redirected warmer air represented by arrow  156  to be combined, thus acting to warm the air stream flow being drawn into air filter box  104 . Thus, the warmer air acts to prevent the build up of snow and/or ice that may block air inlet  116 . Moreover, the opened valve acts to hold the intake manifold pressure so as to not exceed the rated cylinder pressure.  
         [0024]     For example, referring to  FIG. 3 , consider an operating environment at higher altitudes where the ambient air temperature is very low. During the initial operation of the locomotive in this environment (i.e. higher altitude and cold ambient air temperature), the initial Gross Horse Power (GHP) is typically at a de-rated value and the Manifold Air Temperature (MAT) may be high. Unfortunately, these conditions are favorable for driving the operating characteristics of the locomotive close to or beyond the recommended operating parameters of the locomotive, represented in  FIG. 3  as the surge line  202 , possibly causing damage to the locomotive turbocharger compressor portion  106 . This is because as the locomotive begins to operate in this environment, the cold ambient air is being drawn into the air inlet  116  of the air filter box  104 . The air filter box  104  filters this air and discharges the filtered air out of the air outlet  118  and into the turbocharger compressor portion  106  via the turbocharger compressor inlet  120 .  
         [0025]     The turbocharger compressor portion  106  compresses the filtered air and discharges the compressed air out of the turbocharger compressor outlet  122 , wherein the compressed air being discharged out of the turbocharger compressor outlet  122  typically reaches temperatures of approximately 400° Fahrenheit. As such, there is a considerable temperature differential between the inlet airflow and the outlet airflow which is a result of a compressor outlet pressure, P out , that is considerably larger than the compressor inlet pressure, P in . Plotting the ratio of the compressor outlet pressure, P out , to the compressor inlet pressure, P in , versus the corrected airflow through the turbocharger gives a graphical representation of the corrected operating characteristics of the turbocharger relative to the surge line  202 , as shown in  FIG. 3 . Ideally, the locomotive should be operating well within the operating range identified as element  210 . However, as can be seen, in the environment stated above, the turbocharger may be operating at or exceeding the design parameters of the turbocharger system  100 .  
         [0026]     To counter this, a recirculation valve is used to re-circulate a portion of at least one of the compressed air and the cooled compressed air (cooled via the intercooler device  108 , although at a much higher temperature than the ambient air) back into at least one of the compressor inlet  120  and the airflow inlet  116  which increases the temperature of at least one of the airflow into the airflow inlet  116  and the airflow into the compressor inlet  120 . Although increasing the temperature of the airflow into at least one of the compressor inlet  120  and the airflow inlet  116  translates into a slightly richer fuel/air mixture by introducing a slightly smaller number of air molecules into the compressor, the change in airflow through the compressor from this is relatively insignificant and does not significantly affect the turbine speed.  
         [0027]     Opening the recirculation valve  102  results in a decrease in boost pressure and turbo speed, the main cause being that by opening the recirculation valve  102  the turbocharger backpressure is reduced and the engine appears to the turbocharger system  100  to be a much larger engine. As such, the compressor outlet pressure, P out , is reduced while the compressor inlet pressure, P in , remains relatively the same, translating to a lower ratio between the compressor outlet pressure, P out , and the compressor inlet pressure, P in . Again, referring to  FIG. 3 , graphically this has the affect of ‘moving’ the initial operating point  200  away from the surge line  202  of the turbocharger  100  by shifting the initial operating point  200  down and to the left to an intermediate operating point  204  for the locomotive having a de-rated GHP. As the locomotive engine  110  continues to operate, the intermediate operating point  204  shifts to a final operating point  206 , as represented by arrow  162 , which represents the locomotive engine operating at a full GHP, but well within the surge margin operating range  210 .  
         [0028]     As shown by  FIGS. 4 and 5 , these ideal operational characteristics were verified via multiple tests at both sea level ( FIG. 4 ) and at a higher altitude ( FIG. 5 ). Referring to  FIG. 4 , as the locomotive engine  110  was operated, the locomotive engine  110  was operating at an initial operating point  301  close to the baseline surge margin  302 . As the compressed air was re-circulated back into the ambient air flow via the re-circulation valve  102  the operating characteristics shifted down and to the right of the surge margin  302  to an intermediate operating point  304 . As the locomotive engine  110  continued to operate and adjust to the re-circulated flow the operating characteristics of the locomotive engine  110  began to operate at a greater efficiency as represented by the final operating point  306 , well within the surge margin operating range  310 .  
         [0029]     Referring to  FIG. 6 , a block diagram illustrating a method  600  for controlling the operating point of a locomotive engine  110  operating at high altitude and in low ambient temperatures is shown and includes operating the locomotive engine  110  to generate an ambient air stream flow into the locomotive engine such that a hot, compressed air stream is generated, as shown in block  602 . The hot, compressed air stream is then injected into a main intercooler device  108  to generate an intercooler air stream, as shown in block  604 . A portion of the intercooler air stream is then diverted toward a controllable re-circulation valve, such as turbocharger re-circulation valve  102 , as shown in block  606 , and the controllable re-circulation valve is operated to generate a combined air stream flow, as shown in block  608 . This is accomplished by injecting the intercooler air stream into the ambient air stream flow such that the intercooler air stream and the ambient air stream combine together to create a combined air stream flow. At this point, the combined air stream flow is injected into the locomotive engine, as shown in block  610 .  
         [0030]     Valve actuation device  103  functions in a manner responsive to the ambient air conditions (such as temperature, etc.), the altitude of the locomotive and a higher horse power. It should also be appreciated that valve actuation device  103  may be controlled manually and/or via any device and/or method suitable to the desired end purpose, such as computer controlled, pneumatically controlled, mechanically controlled, electrically controlled or any combination thereof. It should be appreciated that, as shown in  FIG. 2 , an optional intercooler device  140  having an optional intercooler inlet  142  and an optional intercooler outlet  144  may be included, as required. This may be utilized to satisfy new emission standards that require the air temperature of the air stream going into the intake manifold to be approximately equal to 100° Fahrenheit. It should also be appreciated that one or both of main intercooler device  108  and/or optional intercooler device  140  may be any type of intercooler device suitable to the desired end purpose, such as a water based intercooler device and/or an air to air intercooler device, and/or any combination thereof.  
         [0031]     In addition to improvements in cold ambient fuel consumption, re-circulating the air back into the air filter box also warms the baggie filters and acts to reduce ice build-up, eliminates the need to control cylinder pressure by de-rating GHP on cold days and improves surge margin under conditions of cold ambient and high MAT.  
         [0032]     While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes, omissions and/or additions may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.