Abstract:
In accordance with an embodiment of the present invention, a method of controlling an internal combustion engine system having an internal combustion engine is disclosed. The internal combustion engine includes an engine block defining a plurality of combustion chambers, an intake air system in fluid communication with the combustion chambers and providing intake air thereto, an exhaust gas system in fluid communication with the combustion chambers and carrying exhaust gas therefrom, a cooling system having a cooling fluid circulated therein and a recirculated gas system in fluid communication with the exhaust gas system and intake air system wherein a portion of the exhaust gas is routed from the exhaust gas system to the intake air system. The method includes sensing at least two internal combustion engine system operating parameters, inputting sensed operating parameters into a controller, storing at least one predetermined constant in the controller, determining a cooling fluid heat threshold using predetermined logic with the controller in response to the at least two internal combustion engine operating parameters and the at least one predetermined constant, and controlling the internal combustion engine system in a predetermined manner in response to reaching the cooling fluid heat threshold.

Description:
TECHNICAL FIELD 
   This invention relates generally to controlling an internal combustion engine, and, more particularly, to a control strategy that prevents a cooling fluid circulated through a heat exchanger from exceeding a predetermined heat threshold. 
   BACKGROUND 
   Typically an internal combustion engine (ICE) has an intake system, exhaust system and cooling system. The ICE may further include a recirculated air system that is controlled by logic, in response to certain engine parameters, so that under predetermined ICE operating conditions, a valve is opened to allow a predetermined portion of exhaust gas to be introduced into the intake system. 
   The recirculated air system may include an exhaust gas cooler, which cools the predetermined portion of exhaust gas before it is introduced into the intake system. The exhaust gas cooler acts as a heat exchanger wherein a cooling fluid contained therein impinges the outer wall of the exhaust gas cooler and absorbs heat from the exhaust gas. Then, the cooling fluid is circulated through a separate heat exchanger where the cooling fluid is cooled. The cooling fluids typically used are oil, water, water mixtures or air. Typically, the most common cooling fluid used within the exhaust gas cooler is a water or water mixture that is also used by the cooling system of the ICE. 
   Under certain ICE operating conditions, the temperature of the exhaust gas may elevate. If the cooling effects of the cooling fluid are insufficient to overcome the elevated temperature of the exhaust gas, the exhaust gas cooler walls may become hot enough to damage the exhaust gas cooler. 
   It is known in the art to sense various temperatures that impact an exhaust gas cooler for a recirculated air system and determine when such temperatures exceed a predetermined threshold in order to monitor when a fault condition occurs. One such fault diagnostic system is described in U.S. Pat. No. 6,085,732 issued to Wang et al. on Jul. 11, 2000. Wang et al. discloses a system and method of sensing either recirculated air temperatures and/or a cooling liquid temperatures and comparing such values to threshold values in order to determine when a fault condition occurs that could damage an exhaust gas heat exchanger or cooler. However, Wang et al. fails to teach being able to prevent the fault condition from occurring, thereby limiting the ability to control the system in a proactive manner that ensures that the exhaust gas cooler is not damaged. 
   The present invention is directed to overcoming one or more of the problems as set forth above. 
   SUMMARY OF THE INVENTION 
   In accordance with an embodiment of the present invention, an internal combustion engine is disclosed. The internal combustion engine system includes an internal combustion engine having an engine block defining a plurality of combustion chambers, an intake air system in fluid communication with the combustion chambers providing intake air thereto, an exhaust gas system in fluid communication with the combustion chambers carrying exhaust gas therefrom, and a cooling system fluidly connected to the internal combustion engine and having a cooling fluid circulated therein. The internal combustion engine system further includes a recirculated gas system in fluid communication with the exhaust gas system and intake air system, wherein a portion of the exhaust gas is routed from the exhaust gas system to the intake air system. The recirculated gas system includes a heat exchanger fluidly connected with the cooling system. The internal combustion engine further includes a controller operatively connected to the internal combustion engine system that is adapted for receiving input signals, sending output signals, storing predetermined constants and storing predetermined logic. The predetermined logic being capable of determining a cooling fluid heat threshold in response to at least two input signals and at least one predetermined constant. 
   In accordance with another embodiment of the present invention, a method of controlling an internal combustion engine system having an internal combustion engine is disclosed. The internal combustion engine includes an engine block defining a plurality of combustion chambers, an intake air system in fluid communication with the combustion chambers providing intake air thereto, an exhaust gas system in fluid communication with the combustion chambers carrying exhaust gas therefrom, a cooling system fluidly connected to the engine block having a cooling fluid circulated therein and a recirculated gas system in fluid communication with the exhaust gas system and intake air system, wherein a portion of the exhaust gas is routed from the exhaust gas system to the intake air system. The recirculated gas system includes a heat exchanger fluidly connected to the cooling system. The method includes sensing at least two internal combustion engine system operating parameters, inputting sensed operating parameters into a controller, storing at least one predetermined constant in the controller, determining a cooling fluid heat threshold in response to the at least two internal combustion engine operating parameters and the at least one predetermined constant, and controlling the internal combustion engine system using predetermined logic with the controller in response to reaching the cooling fluid heat threshold. 
   In accordance with yet another embodiment of the present invention, a control system for a device producing a heated fluid is disclosed. The device has a heat exchanger with a cooling fluid circulated therein for cooling the heated fluid. The control system includes a controller operatively connected with the device and adapted for receiving input signals, sending output signals, storing predetermined constants and predetermined logic, the predetermined logic being capable of determining a cooling fluid heat threshold in response to at least two input signals and at least one predetermined constant. 
   In yet another embodiment of the present invention, a method of controlling a device that produces a heated fluid is disclosed. The device has a heat exchanger with a cooling fluid circulated therein for cooling the heated fluid. 
   The method comprises the steps of sensing at least two operating conditions of the device, inputting sensed operating conditions into a controller, storing at least one predetermined constant in the controller, determining a cooling fluid heat threshold in response to the at least two operating conditions of the device and the at least one predetermined constant and controlling the device using predetermined logic with the controller in response to reaching the cooling fluid heat threshold. 
   It is to be understood that both the foregoing and general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic view of an internal combustion engine incorporating an embodiment of the present invention; and 
       FIG. 2  is a flowchart showing logic for the embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   Referring to  FIG. 1 , there is shown a diagrammatic representation of an exemplary internal combustion engine system  100  incorporating an embodiment of the present invention. The internal combustion engine system  100 , hereafter known as the ICE system, is that of a four-stroke, diesel engine. The ICE system  100  includes an internal combustion engine  102 , hereafter known as the ICE, having an engine block  104  defining a plurality of combustion chambers  106 , the number of which depends on the particular application. In the exemplary ICE  102 , six combustion chambers  106  are shown, however, it should be appreciated that any number of combustion chambers  106  may be applicable with the present invention. Although not shown, associated with each combustion chamber  106  is: a fuel injector, a cylinder liner, at least one intake air port and corresponding intake valve, at least one exhaust gas port and corresponding exhaust valve, and a reciprocating piston moveable within each cylinder liner to define, in conjunction with the cylinder head, each such combustion chamber  106 . 
   The ICE system  100  may include a plurality of sensors including, but not limited to, ICE speed sensor  107 , atmospheric pressure sensor  109  and ICE fuel rate sensor  111 , which are capable of outputting a signal indicative of ICE speed, atmospheric pressure and ICE fuel rate, respectively. The location of the plurality of sensors, as shown, is exemplary and the location is a matter of preference and not limited by the present invention. 
   The illustrated ICE system  100  includes a cooling system  108 , an intake air system  110 , an exhaust gas system  112 , a recirculated gas system  114  and a controller  116 . 
   The cooling system  108  is operatively connected to the ICE  102  and is well known in the art as a cooling liquid system, which includes a fan (not shown), a heat exchanger, also known as a radiator (not shown), a drive pump  117  and a conduit (not shown) for interconnecting the radiator (not shown) to the ICE  102 . In the embodiment of the present invention, a cooling liquid is used as a cooling fluid and is a water and glycol mixture, however, it should be appreciated that other mixtures or cooling fluids may be used, such as, oil, water, other water mixtures or air. It should be appreciated that the cooling fluid has characteristics, such as, but not limited to, a vaporization or boiling point, a flow rate, a temperature, a pressure and the like. The cooling system  108  may include a cooling fluid temperature sensor  115  in fluid communication with the cooling fluid that is capable of outputting a signal indicative of the cooling fluid temperature and/or pressure. The location of the cooling fluid temperature sensor  115 , as shown, is exemplary and the location is a matter of preference and not limited by the present invention. Further, the drive pump  117  may be a variably controlled water pump but any suitable pump or device may be used to circulate the cooling fluid through the cooling system  108 . 
   The intake air system  110  includes an intake manifold  118  removably connectable to the engine block  104  and in fluid communication with the combustion chambers  106 . In addition, the intake air system  110  includes one or more intake air compressors  120 , an intercooler  122  and a throttle valve  124 , all fluidly coupled by an intake air conduit  126 . The intake air compressors  120  could be, but not limited to, a traditional turbocharger known in the art, an electric turbocharger, a supercharger and the like. Although two intake air compressors  120  are shown, it should be appreciated that the number of intake air compressors  120  is a matter of choice and not limited by the present invention. 
   The exhaust gas system  112  includes an exhaust manifold  128  removably connectable to the engine block  104  and in fluid communication with the combustion chambers  106 , an intake air compressor drive  130  and a particulate matter filter  132 , all fluidly coupled by an exhaust gas conduit  134 . The exhaust manifold  128  is shown as a single-part construction for simplicity, however, it should be appreciated that the exhaust manifold  128  may be constructed as multi-part or split manifolds, depending upon the particular application. Exhaust gas generated from the ICE  102  flows through the exhaust gas system  112  and possesses characteristics, such as, but not limited to, a flow rate, a temperature and the like. Further, the exhaust gas system  112  includes a means  135  for sensing the exhaust temperature, such as an exhaust gas temperature sensor, in fluid communication with the exhaust gas and capable of outputting a signal indicative of the exhaust gas temperature and/or pressure. In the embodiment shown, the sensing means  135  is an exhaust gas temperature sensor located downstream of the particulate matter filter  132 , however, it should be appreciated that the location of the exhaust gas temperature sensor  135  could be upstream or within the particulate matter filter  132  and, therefore, is contemplated in the present invention. Further, the exhaust gas system  112  includes an oxidation catalyst  133  downstream of the particulate matter filter  132 . Again, it should be appreciated that the location of the oxidation catalyst  133  could be upstream of the particulate matter filter  132  or excluded from the exhaust gas system  112  without deviating from the scope of the present invention. 
   A regeneration management system, such as an auxiliary regeneration device  137  is included in the exhaust gas system  112 , in communication with the particulate matter filter  132 . The auxiliary regeneration device  137  may be electrical, chemical, gaseous or other suitable type. It is understood, however, that other regeneration management systems may be used, as well, including, but not limited to, dosing, thermal management, passive regeneration or any suitable system. 
   The intake air compressors  120  and air compressor drive  130  are illustrated as part of a turbocharger system  136 . The turbocharger system  136  shown is a first turbocharger  138  and may include a second turbocharger  140 . The first and second turbochargers  138 , 140  may be arranged in series such that the first turbocharger  138  provides a first stage of pressurization and the second turbocharger  140  provides a second stage of pressurization. 
   The recirculated gas system  114  shown is typical of a low-pressure recirculated gas system for an ICE system  100 , however, it should be appreciated that other types of recirculated gas systems  114  may be applicable, such as, but not limited to, high-pressure or moderate-pressure systems or combinations thereof. The recirculated gas system  114  includes a heat exchanger, also known as an exhaust gas cooler  142 , a recirculated gas sensor  144  and a recirculated gas valve  146  all fluidly coupled by a recirculated gas conduit  148 . The recirculated gas sensor  144  is capable of outputting a signal indicative of the recirculated gas temperature and/or pressure. In the embodiment of the present invention, the recirculated gas sensor  144  is a mass air flow sensor well known in the art. 
   In the embodiment shown, the exhaust gas cooler  142  is fluidly connected to the cooling system  108  and has a cooling fluid therein that is shared with the cooling system  108 . Although the exhaust gas cooler  142  is shown fluidly connected to the cooling system  108 , it should be obvious that the exhaust gas cooler  142  may be independent from the cooling system  108  without deviating from the present invention. In such case, any inputs related to the cooling system  108  and described herein would be similarly applicable to the exhaust gas cooler  142 . Further, in such case, it should be understood that other mixtures or cooling fluids might be used within the exhaust gas cooler  142 , such as, oil, water, other water mixtures or air. The exhaust gas cooler  142  is structured to have a cooler inlet  149  and a cooler wall  150  with an outer surface  152  where cooling fluid impinges and an inner surface  154  where recirculated exhaust gas impinges. 
   The controller  116  is operatively coupled with the ICE system  100  and is capable of receiving sensor input signals, outputting signals, storing predetermined data and storing predetermined logic. 
   The controller  116 , in the embodiment shown, receives sensor input signals from one or more of the atmospheric pressure sensors  109 , the cooling fluid temperature sensor  115 , ICE speed sensor  107 , ICE fuel rate sensor  111 , exhaust gas temperature sensor  135  and recirculated gas temperature sensor  144 . However, it should be appreciated that the controller  116  may receive sensor inputs from any other sensors that sense characteristics within the ICE system  100 , which include, but are not limited to, sensors internal or external to such ICE system  100 . 
   The controller  116 , in the embodiment shown, outputs signals to one or more of the ICE  102 , throttle valve  124 , recirculated gas valve  146 , auxiliary regeneration device  137 , drive pump  117  and/or operator alert device  155 . However, it should be appreciated that the controller  116  is not limited to these outputs and may output signals dependent upon the desired application or intended result. The controller  116  includes at least one predetermined control strategy (not shown) in communication with controller output signals. 
   The controller  116 , in the embodiment shown, stores predetermined data such as constants for the ICE system  100  and exhaust gas cooler  142 . The constants for the ICE system  100  may include, but are not limited to, ICE speed, ICE fuel rate, cooling fluid pressure, cooling fluid heat threshold temperature, density of the cooling fluid, cooling fluid type, cooling fluid volume flow through the exhaust gas cooler  142 , specific heat of the exhaust gas, and temperature change in the recirculated gas conduit  148 . The constants for the exhaust gas cooler  142  may include, but are not limited to, at least one heat transfer map and at least one heat threshold map. 
   The controller  116 , in the embodiment shown, stores predetermined logic, such as the at least one predetermined control strategy (not shown) and logic  200  that determines a cooling fluid heat threshold in response to one or more inputs and predetermined stored data. In combination with the at least one predetermined control strategy (not shown), the controller  116  outputs signals to the ICE system  100  in response to determining when cooling fluid heat threshold has been reached. 
   Referring to  FIG. 2 , the cooling fluid heat threshold logic  200  will be discussed in further detail. Blocks  202 ,  204  and  206  input data into the cooling fluid heat threshold logic  200 . The cooling fluid heat threshold logic  200  calculates the cooling fluid heat threshold in blocks  208  through  220 . The cooling fluid heat threshold logic  200  then sends at least one output signal to the ICE system  100 , represented by block  222  dependent on the, at least one predetermined control strategy (not shown). 
   INDUSTRIAL APPLICABILITY 
   In typical operating conditions of the exemplary ICE system  100 , air enters the intake air system  110  and is compressed by the turbocharger system  136 . After passing through the intercooler  122 , the compressed intake air enters the combustion chambers  106  via the intake manifold  118  and the intake port (not shown). The compressed intake air combusts, resulting in exhaust gas, which then exits the combustion chambers  106  via the exhaust port (not shown) and the exhaust manifold  128 . The exhaust gas exits the ICE system  100  via the turbocharger system  136 , passing through the particulate matter filter  132 . 
   Under predetermined operating conditions, and, in response to at least one operating parameter of the ICE system  100 , a portion of the exhaust gas is routed through the recirculated gas system  114  and into the intake air system  110 , via the recirculated gas valve  146 , which is controlled by the controller  116  in response to the at least one operating parameter. 
   The recirculated exhaust gas flowing through the exhaust gas cooler  142  impinges on the inner surface  154  resulting in a heating effect on the cooler wall  150 . In addition, cooling fluid from the cooling system  108  impinges on the outer surface  152  of the cooler wall  150  and the cooling fluid has a cooling effect on the cooler wall  150 . The cooling fluid heat threshold logic  200  determines when the cooling fluid heat threshold has been reached. The cooling fluid heat threshold is a peak temperature or temperature range of the cooling fluid that allows the temperature of the cooler wall  150  to remain below a point where the exhaust gas cooler  142  is damaged. In the embodiment shown, the targeted cooling fluid heat threshold is a temperature or temperature range near the boiling point of the water and glycol mixture. However, it should be understood that the cooling fluid heat threshold is determined by the particular cooling fluid used within the exhaust gas cooler  142 . For instance, if the cooling fluid within the exhaust gas cooler  142  were air, then the cooling fluid heat threshold would be different than for the water and glycol mixture. Therefore, it should be appreciated that the cooling fluid heat threshold is a peak temperature or temperature range for the particular cooling fluid wherein the exhaust gas cooler  142  is not damaged by excessive heat. 
   Referring to the cooling fluid heat threshold logic  200  in  FIG. 2 , the cooling fluid heat threshold logic  200  receives sensor inputs  202 , ICE system constants  204  and cooler constants  206  which will be used to determine the cooling fluid heat threshold. Initially, the cooling fluid heat threshold logic  200  determines the cooling fluid temperature and the cooling fluid pressure at cooler inlet  149 , at block  208 . In the embodiment of the present invention, the cooling fluid temperature at cooler inlet  149  is determined by inputs from the cooling fluid temperature sensor  115 , cooling fluid type constant, ICE fuel rate sensor  111 , ICE speed sensor  107 , ICE fuel rate constant and ICE speed constant. The cooling fluid pressure at cooler inlet  149  is determined by inputs from the atmospheric pressure sensor  109 , cooling fluid pressure constant, ICE speed sensor  107  and ICE speed constant. 
   Next, the heat threshold of the cooling fluid at the cooler inlet  149  is determined at block  210 . In the embodiment of the present invention, the heat threshold of the cooling fluid at the cooler inlet  149  is determined by inputs from the cooling fluid pressure at cooler inlet  149 , calculated in block  208 , and cooling fluid threshold temperature constant. 
   Then, block  212  determines the heat threshold margin at the cooler inlet  149 . In the embodiment of the present invention, the heat threshold margin at the cooler inlet  149  is determined by inputs from the heat threshold of the cooling fluid at the cooler inlet  149 , calculated in block  210 , and the cooling fluid temperature at cooler inlet  149 , calculated in block  208 . 
   It should be understood that although the cooler inlet  149  is designated in  FIG. 2  as a specific location, the components or sensors used for sensing the conditions or parameters in blocks  208 ,  210  and  212  at such cooler inlet  149  may be at positioned at various locations throughout the ICE system  100  so long as there is a corresponding or extrapolated relationship with the conditions or parameters at the cooler inlet  149 . 
   Next, block  214  determines the cooling fluid mass flow. In the embodiment of the present invention, the cooling fluid mass flow is determined by inputs from the density of the cooling fluid constant and cooling fluid temperature at cooler inlet  149 , calculated in block  208 . Then, the cooling fluid mass flow is determined by inputs from the density of the cooling fluid constant, ICE speed sensor  107 , ICE speed constant and the cooling fluid volume flow through the cooler constant. 
   Then, block  216  determines the cooler heat load. In the embodiment of the present invention, the cooler heat load is determined by inputs from the exhaust gas temperature sensor  135  and the recirculated gas temperature sensor  144 . 
   Next, block  218  determines the heat threshold. In the embodiment of the present invention, the heat threshold is determined by inputs from the cooler heat load, calculated in block  216 , at least one heat threshold map constant and the heat threshold margin at the cooler inlet  149 , calculated in block  212 . 
   Then, block  220  determines the cooling fluid heat threshold. In the embodiment of the present invention, the cooling fluid heat threshold is determined by inputs from the heat threshold, calculated in block  218 , and the cooling fluid mass flow, calculated in block  214 . 
   Finally, the cooling fluid heat threshold logic  200  communicates that the cooling fluid heat threshold has been reached to the at least one predetermined control strategy, which, in turn, outputs signals to one or more of the ICE  102 , throttle valve  124 , recirculated gas valve  146 , auxiliary regeneration device  137  and drive pump  117  in order to control the respective operating parameters of the ICE system  100 . The ability to control various operating parameters within the ICE system  100  ensures that the cooling fluid will not exceed the cooling fluid heat threshold. Further, it is anticipated that in the embodiment of the present invention, the at least one predetermined control strategy may also provide an output signal to the operator alert device  155  in order to alert an operator of an event occurring with the ICE  102 , throttle valve  124 , recirculated gas valve  146 , auxiliary regeneration device  137  and drive pump  117  and/or the condition of the exhaust gas cooler  142 . 
   It should be appreciated that other logic means may be used for determining the cooling fluid heat threshold without deviating from the present invention. Also, it should be appreciated that although the present invention is described for use within a recirculated gas system  114  for an ICE system  100 , any heat exchanger for an ICE system having at least one cooling fluid circulated therein and one heated fluid circulated for cooling therethrough is contemplated within the scope of the present invention. Further, it should be appreciated that although the present invention is described for use with an ICE system  100 , any system or device that produces a heated fluid, such as, but not limited to, a furnace, a heat pump and the like, and that also utilizes a heat exchanger for cooling such heated fluid is contemplated within the scope of the present invention. It should be appreciated that if a heat exchanger is used that is not within a recirculated gas system, the inputs signals and predetermined constants for the determination of the cooling fluid heat threshold may be related to the cooling fluid, heated fluid, heat exchanger, system or device, components in such system or device and/or other internal or external conditions or parameters impacting the foregoing. Furthermore, it should be appreciated that the control strategy would include controlling at least one operating parameter of the system or device. In such case, the output signals from the controller would vary dependent on the system or device being used and based on the operating conditions or parameters for such system or device. Therefore, the output signals would be sent to various components within the system or device in order to control the operating parameters in a manner wherein the respective heat exchanger is not damaged by exceeding the cooling fluid heat threshold.