Abstract:
A method and system for detecting and correcting a Hot Manifold condition that occurs in turbocharged diesel engines where intake air used for combustion exceeds an acceptable operating temperature where sensors monitor conditions indicative of the Hot Manifold condition and power level reduction, speed control limits, varying coolant system operations, and cycling flow valves are controlled by a processor to correct the Hot Manifold condition.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to turbocharged diesel engines and more specifically to a method and control system for correcting a condition that occurs when intake air used for combustion inside of a turbocharged diesel engine exceeds an acceptable operating temperature. 
     Turbocharged diesel engines are often used to power locomotives. The turbocharger compresses the air, providing more air for combustion. However, the process of compressing the air increases the temperature of the air. In order for the turbocharged diesel engine to perform properly, the air being supplied for combustion must not exceed a certain temperature limit. Proper air temperature is normally maintained with a heat exchanger that uses a cooling medium, such as water, to reduce the air temperature after leaving the turbocharger. This cooled air then travels to the cylinders via an air-intake manifold. 
     During operation though, problems or operating conditions may arise that result in the intake manifold air temperature exceeding a maximum allowable temperature limit. The elevated temperature may result in operating characteristics which could lead to engine damage or failure. This condition is known as a Hot Intake Manifold or Hot Manifold condition. 
     Instead of replacing existing turbocharged diesel engines with new engines mechanically designed to better control air temperature, the locomotive industry would benefit from a system which takes corrective action when a Hot Intake Manifold condition is detected. Currently, when a Hot Manifold condition is experienced, all power is removed and the engine is simply idled which results in the engine being unusable until it is returned to a maintenance facility for repair. 
     Towards this end, it would be beneficial to have a method and control system which upon identifying a Hot Manifold condition automatically attempts to correct the Hot Manifold condition without or with minimum human interface, and even if the condition is not fully corrected, it would be desirable to provide a system and method that would allow the locomotive engine to continue operating at a safe operating level. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a method for detecting a Hot Manifold condition in an internal combustion engine comprising determining whether to initiate correction of said Hot Manifold condition based on received samples of monitored data indicative of said Hot Manifold condition. The present invention also comprises a method for correcting a Hot Manifold condition upon detection of the condition in an internal combustion engine comprising limiting the engine to a predetermined speed; applying a throttle level threshold limit; and varying a cooling system&#39;s mode for cooling the engine&#39;s cylinders and intercoolers. The present invention also comprises a control system for detecting and correcting the Hot Manifold condition within an internal combustion engine, the system comprising a processor for determining when to initiate and correct a Hot Manifold correction strategy based on received monitored data indicative of the Hot Manifold condition; a plurality of sensors to measure temperature at various engine locations, wherein the processor is operable to determine and change operating conditions of the engine when determining whether to initiate the Hot Manifold correction strategy and in correcting the Hot Manifold condition. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention, reference may be had to the following detailed description taking in conjunction with the accompanying drawings in which: 
     FIG. 1 shows a simplified schematic of an exemplary locomotive that may benefit from a control system embodying the present invention for determining and correcting a Hot Manifold condition; 
     FIG. 2 is a flow chart for determining when a locomotive should utilize a Hot Manifold Correction Strategy; and 
     FIG. 3 is a flow chart of the Hot Manifold Correction Strategy. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows an exemplary control system used to determine and correct a Hot Manifold condition. In one preferred embodiment, the locomotive  5  uses a computer or processor  8  to monitor and control an engine cooling control system  15 , which is integrated with several temperature sensors  10 ,  11 ,  12 . As will be understood by those or ordinary skill in the art, FIG. 3 does not illustrate cooling valves. The cooling system  15  includes cooling valves and a cooling mode which involves a radiator, cylinders, piston housing, and intercoolers. 
     When correcting a Hot Manifold condition, the processor  8  also monitors and controls a throttle level  13  of the locomotive, speed of the locomotive  14 , and operation mode  16  of the locomotive. One temperature sensor  10  is positioned to measure the ambient air temperature. Another temperature sensor  11  is positioned to measure the temperature of the locomotive engine to assess if a Hot Manifold condition is developing. A third temperature sensor  12  is positioned to measure the water temperature used to control the valves and radiator fan of the engine cooling system. Based on the sensor readings, the computer  8  controls the engine  17  and the cooling system  15  to prevent a Hot Manifold condition. The computer  8  also includes a monitor or monitor station  20  that displays messages to an on-board operator when the locomotive  5  experiences a Hot Manifold condition, and the computer  8  also maintains, in a memory storage device  21 , a permanent historical record of Hot Manifold conditions experienced for use during maintenance of the locomotive. 
     FIG. 2 is a flow chart for determining when a locomotive should execute a Hot Manifold Correction Strategy. The system starts at step  23  by determining at step  25  whether a Hot Manifold condition exists. For example, if two consecutive engine temperature samples both confirm a Hot Manifold condition, the system next makes a determination at step  27  as to the present power level of the locomotive engine. If the locomotive is operating at a power level that is above a given threshold power, for a predetermined time, the system will then proceed to the Hot Manifold Correction Strategy  30  as described in the context of FIG.  3 . In one exemplary embodiment used on a General Electric manufactured locomotive, the power limit threshold is set to correspond to throttle notch position N 4 , and the predetermined time is five seconds. It will be appreciated by those skilled in the art that other values for the foregoing parameters may be used depending on the specific locomotive application. 
     If the power level threshold is not exceeded within the designated time, the system will measure at step  32  the ambient air temperature to verify whether the ambient air is above a given temperature threshold. In one exemplary embodiment, the ambient air temperature threshold is 109° F. which is actually 99° F. plus ten degrees to account for an offset of sensor temperature from actual ambient temperature. If the system continues sensing that ambient air temperature is less than the threshold temperature after a designated time, such as five minutes, after determining at step  27  that the Hot Manifold Correction Strategy  30  is not needed, the system will assume a bad or defective manifold temperature sensor is causing this reading, and log at step  35  a non-restrictive fault record of the event to indicate a bad manifold sensor. 
     If the ambient temperature is more than the threshold temperature, the system will then determine at step  37  whether the engine is in an idle mode, that is, the engine  17  is not in another operation mode, such as motoring, braking, self load, self open, Head End Power (HEP) standby, or HEP normal operation mode. If the engine  17  is in idle, the control system will log at step  40  a restrictive fault if this condition continues for a designated time period. In one exemplary embodiment, the control system will not log at step  40  a restrictive fault until the fault is detected for a time period of three hundred seconds. 
     If the test at step  37  for idle determines that the engine  17  is not in idle, the control system will override at step  42  the engine speed to operate at a predetermined number of revolutions per minute (RPM) such as 1050 RPM. This override condition will reset when the throttle returns to idle for a predetermined time period, such as ten seconds. 
     FIG. 3 is a flow chart of the Hot Manifold Correction Strategy. Upon entering the Hot Manifold Correction Strategy  30 , the control system logs at step  45  a non-restrictive fault, and a text message is displayed to an on-board operator. A record of this occurrence is also recorded in the computer&#39;s memory. The control system then overrides at step  47  the engine speed whereby the engine then operates at a predetermined RPM, such as 1050 RPM. This override at step  47  will reset when the throttle returns to idle for a predetermined period, such as ten seconds in one exemplary embodiment. The control system then tests at step  49  for an operating mode of the cooling system where the cooling water supply for both the diesel engine cylinders and the intercoolers is being circulated through the radiators. This operating mode of the cooling system is referred to as Mode 1. 
     As will be understood by those skilled in the art, generally there may be two distinct requirements for cooling a turbocharged diesel engine. For example, some of the cooling water is used to cool the cylinders, specifically the piston housing, and some of the cooling water is used to cool the intake manifold air via the intercoolers. Accordingly, there are two additional distinct cooling system modes addressed by the Hot Manifold Correction Strategy of the present invention, e.g., Mode 2 and Mode 3. Mode 2 refers to the operating mode where the water used to cool the engine cylinders is circulated through the radiators but the water supply for the intercoolers is taken from the water returned from the diesel engine cylinders. Mode 3 refers to the operating mode when there is no available cooling water from the radiators. In this mode, the water supply for the intercoolers is taken from the water being returned from the diesel engine cylinders. Mode 3 is established because, as suggested above, water is not always present in the radiator, and under some conditions water is sent to the radiator only when cooling is necessary. 
     If the cooling system is not calling for Mode 1 operation, then the control system will limit the engine at step  50  to the predetermined engine power level, such as notch level N 4  in one exemplary embodiment, and notify the on-board user that the engine is in a limited load operation mode via the computer monitor  20  or other suitable message board. The locomotive will continue operating in this restricted mode until conditions are met which will cause the locomotive to no longer operate in the Hot Manifold Correction Strategy mode  30 . 
     To determine when the locomotive may leave the Hot Manifold Correction Strategy, the control system will begin by determining at step  53  if a Mode 3 call is initiated. If a Mode 3 call is initiated, then the control system will reset at step  55  the RPM override, remove the power level restriction, and then leave the Hot Manifold Correction Strategy  30  and begin operating normally at step  57 . If the Mode 3 call is not initiated, the control system will determine at step  60  whether the system is in an idle mode for a given time, such as 10 seconds. If the engine is in the idle mode, then the control system will reset at step  55  the RPM override, remove the power level restriction, and then leave the Hot Manifold Correction Strategy  30  and begin operating normally  57 . If the control system has not idled for a given time, such as ten seconds, then the control system will again test at step  53  for a Mode 3 call and repeat the above discussed steps  55 ,  57 ,  60  until such time that one of the above steps allows the system to return to normal operation. 
     If the control system tests at step  49  positive for a Mode 1 operating call, the control system will check at step  63  the control temperature. As suggested above, the control temperature may be determined by sensors placed to record the engine inlet water temperature. If the control temperature exceeds a predetermined temperature, such as 200° F. in one exemplary embodiment, the system will override Mode 1 and go to Mode 2 at step  65 . The control system will then limit at step  50  the engine to the predetermine power level, such as notch level N 4 , and notify the on-board user that the engine is in a limited load operation mode via the computer monitor  20 . The locomotive will continue operating in this restricted mode until the above mentioned tests and conditions at steps  50 ,  53 ,  60 ,  55  are met which causes the locomotive to no longer operate in the Hot Manifold Correction Strategy mode  30 . 
     If the control temperature test executed at step  63  determines that the temperature is less than or equal to the predetermined temperature such as 200 F., the control system will cycle at step  67  the respective state of the flow magnet valves of the coolant valves at a predetermined rate, such as one complete cycle of on/off or off/on every second for three seconds or three full cycles total. The cooling valves should preferably be returned to their respective original state unless a new mode requirement was received during the cycling. The control system should then override at step  70  Mode 1 to Mode 2. The control system should then limit at step  73  the power level to a predetermined level, such as to notch level N 4 , and display a message to the on-board user about the load limit. After waiting at step  75  a designated period, such as forty-five seconds, the system should remove the power level restriction. This cycling should only occur once prior to the forty-five second wait period of this Hot Manifold Correction Strategy. The cycling of the flow magnet valves shall not interfere with normal operation of the radiator fan. 
     As illustrated in FIG. 3, the control system should then perform the test executed at step  77  to determine if a Hot Manifold condition still exists. If the control system detects a Hot Manifold condition, then the control system will continue to limit at step  50  the engine to the predetermine power level, notch level N 4  in one exemplary embodiment, and continue notifying the on-board user that the engine is still in a limited load operation mode via the computer monitor  20 . The locomotive will continue operating in this restricted mode until tests and the respective conditions based upon steps  53 ,  60 ,  55  are met which causes the locomotive to no longer operate in the Hot Manifold Correction Strategy mode  30 . 
     If the Hot Manifold condition does not exist, the control system should then test at step  80  for Mode 3 call. If it does exist, the control system should reset at step  55  the RPM override, reset Mode 2 override and return to normal operation at step  57 . If the Mode 3 call does not exist, the control system will determine at step  83  if the engine  17  has idled for a given time, such as ten seconds. If the engine  17  has idled for the given time, the control system will reset at step  55  the RPM override, reset Mode 2 override and return to normal operation at step  57 . If the engine  17  has not idled for the given time period, the control system will again test at step  77  for a Hot Manifold condition as depicted in FIG.  2 . 
     While the invention has been described in what is presently considered to be the preferred embodiment, many variations and modifications will become apparent to those skilled in the art. Accordingly, it is intended that the invention not be limited to the specific illustrative embodiment but be interpreted within the full spirit and scope of the appended claims.