Patent Grant
10508621
Technical Field
Embodiments of the subject matter described herein relate to an exhaust gas recirculation (EGR) system, a cooler for that system, and associated methods.
Discussion of Art
Engines may utilize recirculation of exhaust gas from an engine exhaust system to an engine intake system, a process referred to as exhaust gas recirculation (EGR). In some examples, a group of one or more cylinders may have an exhaust manifold that is coupled to an intake passage of the engine such that the group of cylinders is dedicated, at least under some conditions, to generating exhaust gas for EGR. Such cylinders may be referred to as “donor cylinders.” In other systems, the exhaust gas may be pulled from a manifold.
Some EGR systems may include an EGR cooler to reduce a temperature of the recirculated exhaust gas before it enters the intake passage. The EGR cooler may be used to reduce exhaust gas temperature from about 1000 degrees Fahrenheit to about 200 degrees Fahrenheit. As the exhaust gases travel through the EGR cooler, heat is transferred to the heat transfer medium flowing through the cooling tubes of the EGR cooler (e.g., water or other coolant).
In an embodiment, an exhaust gas recirculation (EGR) cooler includes a first section and a second section. The first section is arranged proximate to an exhaust gas inlet of the EGR cooler and includes a first plurality of tubes and a first plurality of fins coupled to the first plurality of tubes, where at least one of the first plurality of tubes and the first plurality of fins are comprised of a first material that has a first coefficient of thermal expansion (CTE). The second section is arranged downstream of the first section and includes a second plurality of tubes and a second plurality of fins coupled to the second plurality of tubes. The second plurality of tubes and the second plurality of fins are comprised of a second material that has a second CTE. The second CTE is greater than the first CTE.
One or more embodiments of the inventive subject matter described herein are directed to a system that includes exhaust gas recirculation (EGR), and an EGR cooler as part of that system, such as the engine systems shown in
The approach described herein may be employed in a variety of engine types, and a variety of engine-driven systems. Some of these systems may be stationary, while others may be on semi-mobile or mobile platforms. Semi-mobile platforms may be relocated between operational periods, such as mounted on flatbed trailers. Mobile platforms include self-propelled vehicles. Such vehicles can include on-road transportation vehicles, as well as mining equipment, marine vessels, rail vehicles, and other off-highway vehicles (OHV). For clarity of illustration, a locomotive is provided as an example of a mobile platform supporting a system incorporating an embodiment of the invention.
The engine 104 receives intake air for combustion from an intake, such as an intake manifold 115. The intake may be any suitable conduit or conduits through which gases flow to enter the engine. For example, the intake may include the intake manifold 115, an intake passage 114, and the like. The intake passage 114 receives ambient air from an air filter (not shown) that filters air from outside of the vehicle in which the engine 104 is positioned. Exhaust gas resulting from combustion in the engine 104 is supplied to an exhaust, such as exhaust passage 116. The exhaust may be any suitable conduit through which gases flow from the engine. For example, the exhaust may include an exhaust manifold 117, the exhaust passage 116, and the like. Exhaust gas flows through the exhaust passage 116.
In the exemplary embodiment depicted in
As depicted in
In the exemplary embodiment shown in
Further, the EGR system 160 includes a first valve 164 disposed between the exhaust passage 116 and the EGR passage 162. The second valve 170 may be an on/off valve controlled by the controller 180 (for turning the flow of EGR on or off), or it may control a variable amount of EGR, for example. In some examples, the first valve 164 may be actuated such that an EGR amount is reduced (exhaust gas flows from the EGR passage 162 to the exhaust passage 116). In other examples, the first valve 164 may be actuated such that the EGR amount is increased (e.g., exhaust gas flows from the exhaust passage 116 to the EGR passage 162). In some embodiments, the EGR system 160 may include a plurality of EGR valves or other flow control elements to control the amount of EGR.
As shown in
In the exemplary embodiment of
The engine system 100 further includes an exhaust treatment system 130 coupled in the exhaust passage in order to reduce regulated emissions. As depicted in
The engine system 100 further includes the controller 180, which is provided and configured to control various components related to the engine system 100. In one example, the controller 180 includes a computer control system. The controller 180 further includes non-transitory, computer readable storage media (not shown) including code for enabling on-board monitoring and control of engine operation. The controller 180, while overseeing control and management of the engine system 102, may be configured to receive signals from a variety of engine sensors, as further elaborated herein, in order to determine operating parameters and operating conditions, and correspondingly adjust various engine actuators to control operation of the engine system 102. For example, the controller 180 may receive signals from various engine sensors including, but not limited to, engine speed, engine load, boost pressure, ambient pressure, exhaust temperature, exhaust pressure, etc. Correspondingly, the controller 180 may control the engine system 102 by sending commands to various components such as an alternator, cylinder valves, throttle, heat exchangers, wastegates or other valves or flow control elements, etc.
As another example, the controller 180 may receive signals from various temperature sensors and pressure sensors disposed in various locations throughout the engine system. In other examples, the first valve 164 and the second valve 170 may be adjusted to adjust an amount of exhaust gas flowing through the EGR cooler to control the manifold air temperature or to route a desired amount of exhaust to the intake manifold for EGR. As another example, the controller 180 may receive signals from temperature and/or pressure sensor indicating temperature and/or pressure of cooling fluid at various locations in a cooling fluid circuit, such as the cooling fluid circuit 216 described below with reference to
The marine vessel 100 further includes a bilge system 190, which, at least in part, removes water from a hull of the marine vessel 100. The bilge system 190 may include pumps, motors to run the pumps, and a control system. For example, the controller 180 may be in communication with the bilge system 190. As depicted in
The exhaust gas directed along the exhaust passage 212 flows through an EGR cooler 214 before it enters the intake passage 208 of the engine 202. The EGR cooler 214 may be a gas-to-liquid heat exchanger, for example, which cools the exhaust gas by transferring heat to a cooling fluid, such as a liquid cooling fluid. After passing through the EGR cooler, the temperature of the exhaust gas may be reduced to approximately 110° C., for example. Once the exhaust gas enters the intake passage 208 and mixes with the cooled intake air, the temperature of the charge air may be approximately 65° C. The temperature of the charge air may vary depending on the amount of EGR and the amount of cooling carried out by the charge air cooler 206 and the EGR cooler 214, for example.
As depicted in
In the exemplary embodiment shown in
As shown, cooling fluid flows from the pump 218 to the EGR cooler 214. Exhaust gas passing through the EGR cooler 214 transfers heat to the cooling fluid such that the exhaust gas is cooled before it enters the intake passage 208 of the engine 202. In the exemplary embodiment shown in
The system 200 further includes a thermostat 220 positioned in the cooling fluid circuit downstream of the engine. The thermostat 220 may be adjusted to maintain an engine out temperature of the cooling fluid (e.g., the temperature of the cooling fluid as it exits the engine), for example. In some examples, the thermostat 220 may be an electronic thermostatic valve; while in other examples, the thermostat 220 may be a mechanical thermostatic valve. In some embodiments, a control system which includes a controller 204, such as the controller 180 described above with reference to
The vessel cooler 222 may be a liquid-to-liquid heat exchanger, for example. As depicted in
Thus, due to the relatively low temperature of the ambient marine water and the liquid-to-liquid heat transfer, the marine water may provide increased cooling of the cooling fluid as compared to air-based cooling systems. As such, a smaller EGR cooler may be used, thereby reducing a size and cost of the cooling system, for example. Further, because the EGR cooler 214 is positioned in series with the engine 202, an amount of cooling fluid flowing through the cooling fluid circuit may be reduced. For example, when the EGR cooler and engine are positioned in parallel, a greater amount of cooling fluid is needed to supply the EGR cooler and engine with similar flows of cooling fluid.
An embodiment relates to a method (e.g., a method for a cooling fluid circuit). The method comprises pressurizing a cooling fluid with a pump, and directing the cooling fluid pressurized by the pump to an exhaust gas recirculation cooler, to cool recirculated exhaust gas from an engine. The method further comprises cooling the engine by directing cooling fluid exiting the exhaust gas recirculation cooler to the engine before returning it to the pump. An example of another embodiment of a method (for a cooling fluid circuit) is illustrated in the flow chart of,
At step 302 of the method, a pump is supplied with cooling fluid. The cooling fluid may be cooled cooling fluid from a vessel cooler, for example. In some examples, the cooled cooling fluid from the vessel cooler may be mixed with cooling fluid exiting an engine such that a temperature of the cooling fluid is increased.
At step 304, the cooling fluid is pressurized via the pump. The output pressure of the pump may be based on a boiling point of the cooling fluid and an expected amount of heat transfer to the cooling fluid by an EGR cooler and/or the engine. For example, the cooling fluid may be pressurized so that the cooling fluid does not exceed its boiling point.
The pressurized cooling fluid is directed from the pump to the EGR cooler at step 306 to cool exhaust gas passing through the EGR cooler for exhaust gas recirculation. For example, heat is transferred from the exhaust gas to the cooling fluid such that the exhaust gas is cooled and the cooling fluid is warmed. At step 308, cooling fluid exiting the EGR cooler is directed to the engine, which is positioned in series with the EGR cooler, to cool the engine. For example, heat is transferred from various components of the engine to the cooling fluid such that a temperature of the cooling fluid increases and the engine is cooled.
At step 310, an engine out temperature of the cooling fluid is determined. As an example, the cooling fluid circuit may include a temperature sensor at an engine cooling fluid outlet. As another example, the temperature of the cooling fluid may be determined at a thermostat.
At step 312, it is determined if the engine out cooling fluid temperature is less than a first threshold temperature. If it is determined that the cooling fluid temperature is less than the first threshold temperature, the method continues to step 314 where the thermostat is closed such that the cooling fluid flow through the engine is reduced. On the other hand, if the engine out cooling fluid temperature is greater than the first threshold temperature, the method moves to step 316 where it is determined if the temperature is less than a second threshold temperature, where the second threshold temperature is greater than the first threshold temperature.
If it is determined that the engine out cooling fluid temperature is less than the second threshold temperature, the method proceeds to step 318 where the thermostat is adjusted such that at least a portion of the cooling fluid bypasses the vessel cooler. In this manner, a temperature of the engine may be maintained at a higher temperature to maintain engine efficiency, for example, even when an amount of EGR is reduced resulting in reduced heat transfer to the cooling fluid from exhaust gas in the EGR cooler. In contrast, if it is determined that the engine out cooling fluid temperature is greater than the second threshold temperature, the method moves to step 320 where all of the cooling fluid is directed to the vessel cooler.
Thus, by positioning the EGR cooler and the engine in series in a cooling fluid circuit, an amount of cooling fluid flowing through the cooling fluid circuit may be reduced, as the cooling fluid flows through the EGR cooler and then the engine. Because the cooling fluid is warmed by the EGR cooler before it enters the engine, less heat exchange may occur in the engine resulting in a higher engine operating temperature and greater thermal efficiency of the engine. Further, because the cooling fluid is pressurized by the pump before it enters the EGR cooler, a possibility of boiling cooling fluid may be reduced.
Another embodiment relates to a system, e.g., a system for a marine vessel or other vehicle. The system comprises a reservoir for holding a cooling fluid, an exhaust gas recirculation cooler, an engine, and a cooling fluid circuit. (The reservoir may be a tank, but could also be a return line or other conduit, that is, the reservoir does not necessarily have to hold a large volume of cooling fluid. The reservoir is generally shown as pointed at by 216 in
Another embodiment relates to a system, e.g., a system for a marine vessel or other vehicle. The system comprises a pump, an exhaust gas recirculation cooler, an engine, and a cooling fluid circuit. The cooling fluid circuit interconnects the pump, the exhaust gas recirculation cooler, and the engine. The cooling fluid circuit is configured to direct cooling fluid pressurized by the pump in series from the pump, to the exhaust gas recirculation cooler, to the engine, and back to the pump (or back to a return line or other reservoir to which the pump is operably coupled for receiving cooling fluid). For example, in operation, the cooling fluid pressurized by the pump travels, in order from upstream to downstream: through a first conduit of the cooling fluid circuit from an outlet of the pump to an inlet of the exhaust gas recirculation cooler; through the exhaust gas recirculation cooler; through a second conduit of the cooling fluid circuit from an outlet of the exhaust gas recirculation cooler to an inlet of a cooling system (e.g., cooling jacket) of the engine; through the cooling system of the engine; and through a third conduit of the cooling fluid circuit from an outlet of the engine cooling system to an inlet of the pump (or reservoir).
The engine receives intake air for combustion from an intake passage 414. The intake passage receives ambient air from an air filter 460 that filters air from outside of the rail vehicle. Exhaust gas resulting from combustion in the engine is supplied to an exhaust passage 416. Exhaust gas flows through the exhaust passage, and out of an exhaust stack of the rail vehicle. In one example, the engine is a diesel engine that combusts air and diesel fuel through compression ignition. In another example, the engine is a dual or multi-fuel engine that may combust a mixture of gaseous fuel and air upon injection of diesel fuel during compression of the air-gaseous fuel mix. In other non-limiting embodiments, the engine may additionally combust fuel including gasoline, kerosene, natural gas, biodiesel, or other petroleum distillates of similar density through compression ignition (and/or spark ignition).
In one embodiment, the rail vehicle is a diesel-electric vehicle. As depicted in
The alternator/generator produces electrical power that may be stored and applied for subsequent propagation to a variety of downstream electrical components. As an example, the alternator/generator may be electrically coupled to a plurality of traction motors and the alternator/generator may provide electrical power to the plurality of traction motors. As depicted, the plurality of traction motors are each connected to one of the plurality of wheels to provide tractive power to propel the rail vehicle. One example configuration includes one traction motor per wheel set. As depicted herein, six traction motors correspond to each of six pairs of motive wheels of the rail vehicle. In another example, alternator/generator may be coupled to one or more resistive grids 426. The resistive grids may be configured to dissipate excess engine torque via heat produced by the grids from electricity generated by alternator/generator.
In some embodiments, the vehicle system may include a turbocharger 420 that is arranged between the intake passage and the exhaust passage. The turbocharger increases air charge of ambient air drawn into the intake passage in order to provide greater charge density during combustion to increase power output and/or engine-operating efficiency. The turbocharger may include a compressor (not shown) which is at least partially driven by a turbine (not shown). While in this case a single turbocharger is included, the system may include multiple turbine and/or compressor stages. Additionally or alternatively, in some embodiments, a supercharger may be present to compress the intake air via a compressor driven by a motor or the engine, for example. Further, in some embodiments, a charge air cooler (e.g., water-based intercooler) may be present between the compressor of the turbocharger or supercharger and intake manifold of the engine. The charge air cooler may cool the compressed air to further increase the density of the charge air.
In some embodiments, the vehicle system may further include an aftertreatment system coupled in the exhaust passage upstream and/or downstream of the turbocharger. In one embodiment, the aftertreatment system may include a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF). In other embodiments, the aftertreatment system may additionally or alternatively include one or more emission control devices. Such emission control devices may include a selective catalytic reduction (SCR) catalyst, three-way catalyst, NOx trap, or various other devices or systems.
The vehicle system may further include an EGR system 430 coupled to the engine, which routes exhaust gas from the exhaust passage of the engine to the intake passage downstream of the turbocharger. In some embodiments, the EGR system may be coupled exclusively to a group of one or more donor cylinders of the engine (also referred to a donor cylinder system). As depicted in
In some embodiments, the EGR system may further include an EGR valve for controlling an amount of exhaust gas that is recirculated from the exhaust passage of the engine to the intake passage of the engine. The EGR valve may be an on/off valve controlled by a controller 410, or it may control a variable amount of EGR, for example. As shown in the non-limiting example embodiment of
As depicted in
As shown in
As shown in
The rail vehicle further includes the controller (e.g., engine controller) to control various components related to the rail vehicle. As an example, various components of the vehicle system may be coupled to the controller via a communication channel or data bus. In one example, the controller includes a computer control system. The controller may additionally or alternatively include a memory holding non-transitory computer readable storage media (not shown) including code for enabling on-board monitoring and control of rail vehicle operation. In some examples, the controller may include more than one controller each in communication with one another, such as a first controller to control the engine and a second controller to control other operating parameters of the locomotive (such as tractive motor load, blower speed, etc.). The first controller may be configured to control various actuators based on output received from the second controller and/or the second controller may be configured to control various actuators based on output received from the first controller.
The controller may receive information from a plurality of sensors and may send control signals to a plurality of actuators. The controller, while overseeing control and management of the engine and/or rail vehicle, may be configured to receive signals from a variety of engine sensors, as further elaborated herein, in order to determine operating parameters and operating conditions, and correspondingly adjust various engine actuators to control operation of the engine and/or rail vehicle. For example, the engine controller may receive signals from various engine sensors including, but not limited to, engine speed, engine load, intake manifold air pressure, boost pressure, exhaust pressure, ambient pressure, ambient temperature, exhaust temperature, particulate filter temperature, particulate filter back pressure, engine coolant pressure, gas temperature in the EGR cooler, or the like. The controller may also receive a signal of an amount of oxygen in the exhaust from an exhaust oxygen sensor 462. Additional sensors, such as coolant temperature sensors, may be positioned in the cooling system. Correspondingly, the controller may control the engine and/or the rail vehicle by sending commands to various components such as the traction motors, the alternator/generator, fuel injectors, valves, or the like. For example, the controller may control the operation of a restrictive element (e.g., such as a valve) in the engine cooling system. Other actuators may be coupled to various locations in the rail vehicle.
With reference to
The EGR cooler includes a housing (e.g., outer housing) 502, and a plurality of cooling tubes 504 disposed within the housing. The cooling tubes allow coolant to flow therethrough and exchange heat with exhaust gas that flows through an interior of the housing, outside of the cooling tubes (e.g., outside of exterior walls of the cooling tubes). As shown at 512, hot exhaust gas flows into the housing of the EGR cooler through an inlet 506 (e.g., a first opening) formed by the housing and then expands within an inlet manifold 526 before entering a body 532 of the EGR cooler which contains the cooling tubes. After passing through the body and flowing around the cooling tubes, the exhaust gas flows through an outlet manifold 528, and then finally exits the EGR cooler out through an outlet 508 (e.g., a second opening) formed by the housing, as shown at 514.
As shown in
To overcome these issues, the leading cooling tubes of the EGR cooler that are positioned closest to the inlet and adjacent to the interior sidewalls of the housing (relative to the rest of the cooling tubes closer to the central axis of the EGR cooler and/or arranged more downstream in the EGR cooler, relative to the flow path of exhaust gas through the EGR cooler) may be removed from the EGR cooler and replaced by one or more interior baffles 510, as shown in
As shown in
Additionally, each interior baffle has a width, in a direction of the vertical axis, which extends from a respective interior sidewall of the EGR cooler housing to the remaining cooling tubes of the first bundle group that are closest to the interior sidewall. As shown in
A front face of the interior baffle, arranged in a plane of the horizontal and vertical axis, as shown in
As shown in
As seen in
In an alternate embodiment, the cooling tubes may be rolled into the corresponding tube sheet instead of welded. In this embodiment, each cooling tube may be mechanically expanded into the tube sheet.
The tube sheets are coupled at a first end (e.g., sidewall) of the tube sheet to a first sidewall of the housing and at a second end (e.g., sidewall) of the tube sheet to a second sidewall of the housing, the second sidewall opposite the first sidewall across the central axis of the EGR cooler housing.
As shown in
As also shown in
Another way to reduce thermal stress on the leading cooling tubes proximate to the EGR cooler inlet and interior sidewalls of the EGR cooler housing includes decreasing the fin density within the regions of these leading cooling tubes. This feature is illustrated in
Over time, due to exhaust gas flowing through the EGR cooler, the EGR cooler may become fouled (e.g., deposits may build up within the EGR cooler and on outer surface of the cooling tubes. This increase in EGR cooler fouling may increase a resistance of exhaust flow through the EGR cooler and decrease the cooling effectiveness of the EGR cooler. In order to reduce and/or remove deposits from the EGR cooler and clean the EGR cooler during engine operation (e.g., while the EGR cooler continues to operate without shutting down the engine), a controller of the engine system (such as controller 130 shown in
The engagement frequency for the EGR cleaning operating mode may be based at least in part on one or more of the age of the engine, the age of the EGR cooler, the type of engine, the engine duty cycle, the time to last oil-change (or service/maintenance event) or the time to next oil-change (service/maintenance event), and the like. Alternatively, it may be a health parameter of the EGR cooler that initiates the cleaning operating mode.
Turning to
At 902, the method includes estimating and/or measuring engine operating conditions. Engine operating conditions may include one or more of engine speed and load, engine temperature, exhaust gas temperature at the exhaust inlet and outlet of the EGR cooler, coolant temperature at a coolant inlet and outlet of the EGR cooler, a pressure drop across the EGR cooler (e.g., pressure difference between the exhaust inlet and outlet of the EGR cooler), an amount of fouling of the EGR cooler, a duration of engine operation, and the like.
At 904, the method includes determining a level of fouling in the EGR cooler (e.g., an amount of fouling within an interior of the EGR cooler). The level of fouling in the EGR cooler may be based on one or more of an EGR cooler effectiveness estimate, a pressure drop across the EGR cooler (e.g., a difference in pressure between the exhaust gas inlet and outlet of the EGR cooler), an amount of fouling of the EGR cooler based on an output of a sensor that measures fouling directly in the EGR cooler (such as sensor 451 shown in
At 906, the method includes determining if the fouling level is above a set, first threshold level. In one example, determining if the fouling level is above the first threshold includes determining if a pressure difference across the EGR cooler (e.g., pressure difference between the exhaust gas inlet and outlet) is greater than a threshold pressure difference. In another example, determining if the fouling level is above the first threshold includes determining if a temperature differential between the exhaust gas inlet and outlet of the EGR cooler is not greater than a threshold. For example, if the temperature of the exhaust gas at the outlet of the EGR cooler is not a threshold amount different than the exhaust gas at the inlet, then the effectiveness of the EGR cooler may be decreased due to fouling. In yet another example, determining if the fouling level is above the first threshold includes determining if an amount of fouling (as determined by a fouling sensor within the EGR cooler) within the EGR cooler is greater than a threshold amount. In this way, a health parameter of the EGR cooler may initiate the cleaning operating mode.
If the fouling level is not greater than the first threshold, the method continues to 908 to determine if it is time to pro-actively initiate a cleaning operating mode of the EGR cooler. As one example, the method at 908 may include determining if a threshold duration has passed since a previous EGR cooler cleaning operation. In this way, the EGR cooler may be pro-actively cleaned via a cleaning mode initiated by the controller at a set engagement frequency. The engagement frequency for the EGR cleaning operating mode may be based at least in part on one or more of the age of the engine, the age of the EGR cooler, the type of engine, the engine duty cycle, the time to last oil-change or the time to next oil-change, and the like.
If it is not time to initiate cleaning of the EGR cooler, the method continues to 910 to continue operating the engine without cleaning the EGR cooler. The method then ends. However, if either it is time to initiate a cleaning mode of the EGR cooler and/or the fouling level of the EGR cooler is above the threshold level, the method continues to 912 to determine if conditions are met for cleaning or reducing fouling of the EGR cooler via port heating. In one example, conditions for enabling a port heating cleaning mode include the engine operating at idle or during dynamic braking. For example, in one embodiment, port heating may be performed with any reverser handle position—e.g., any operating mode where the notch call is zero. Further, when locomotives are the vehicles in which the engine is installed, and there are two or more locomotives in consist, one locomotive may communicate to the other so that neither of the locomotives are in port heating operating mode at the same time. In another example, conditions for port heating may be met when engine load is below a threshold (e.g., low load) and after the engine has experienced conditions that put the engine at risk for oil in the exhaust (e.g., after the engine has been at low load for a duration that may be a relatively extended period of time). In yet another example, the controller may determine one or more of an accumulated engine revolutions at low or no load, the load amount, and engine revolutions as a function of MW-hrs as at least one factor in determining whether to initiate the EGR cooler cleaning mode of operation.
If conditions for initiating the port heating cleaning mode are met at 912, the method continues to 914 to initiate port heating. In one embodiment, a port heating event may include over-fueling (e.g., via actuating a fuel injector of at least one cylinder to increase the amount of fuel injected into the cylinder) a determined number of cylinders. The determined number of cylinders may include one or more of the engine cylinders. An amount of over-fueling (e.g., amount of additional fuel injected) may be based on one or more of the age of the engine, the age of the EGR cooler, accumulated megawatt hours, the type of engine, the engine duty cycle, the time to last oil-change or the time to next oil-change, and the like. In some example, the EGR cooler cleaning operating mode may be accomplished at a determined speed other than at idle or at low load/speed. Further, the period of time for which the system is operated in the port heating mode may be controlled based on at least one or more of the following: the number of cylinders being used, the period of time since the last cleaning event, the amount of pressure dropped sensed through the EGR cooler, other engine performance perimeters, and the like. The frequency or the period between port heating cycles may be further determined based on one or more of the following: time, a measure of the accumulated engine revolutions at low or no load, the load amount, and engine revolutions as a function of MW-hrs of accumulated use of the engine and/or the EGR cooler. After the period of time for port heating has expired, the method continues to 916 to terminate the EGR cooler cleaning mode and continue operating the engine. In this way, port heating may heat the exhaust that passes through the EGR cooler, thereby vaporizing oil or combusting the oil within the system. During port heating, condensing of the oil/fuel/incomplete combustion contaminants in the engine may be reduced.
Returning to 912, if the conditions for port heating are not met, the method continues to 918 to activate an alternate cleaning mode of the EGR cooler (which may include initiating one or more of the methods shown at 918). As shown at 920, activating an alternate cleaning operating mode may include, providing via the controller late fuel injection and/or late post injections to one or more engine cylinders. This may include activating one or more fuel injectors to retard the timing of regular or post fuel injection events at one or more cylinders. In another example, at 922, activating an alternate cleaning mode may include auto-loading the engine while operating in idle. If extended idle presents a need to remove oil carry-over, the system would transition itself into a self-load mode. The self-load mode causes the engine to generate power that is then dissipated in the dynamic braking grids (rather than as motive force from the traction motors). The engine would make enough power to heat the exhaust and to remove the oil (e.g., fouling material). In yet another example, at 924, activating an alternate cleaning mode may include actuating the exhaust valves to back-pressure the engine. Such back pressuring may make the engine perform indicated work (due to pumping losses) without it being brake work. In another example, at 926, activating an alternate cleaning mode may include actuating an electrical or other heater element in the exhaust manifold which would heat the EGR cooler (e.g., due to the EGR cooler being positioned proximate to the exhaust manifold) without the need to raise the exhaust gas temperature.
From 916 and 918, the method continues to 928 set a diagnostic flag for cleaning the EGR cooler once the engine is shut down based on one or more of a number of times an active cleaning operating mode has been executed (e.g., one of the methods at 914 and 918), a rate of fouling of the EGR cooler (which may be based on the determined level of fouling at the EGR cooler and/or a frequency of the EGR cooler cleaning mode operation), and/or a determined level of fouling in the EGR cooler being above a second threshold which is greater than the threshold at 904. For example, the method at 928 may include providing a signal for maintenance to one or more of the operator of the equipment, a service or maintenance shop, and a back office that monitors and schedules maintenance and repairs for equipment.
At 930, the method may optionally include determining if the level of fouling and/or frequency of EGR cooler cleaning events are greater than a second threshold. As an example, the second threshold may be a level that is higher than the level for initiating an active EGR cooler cleaning mode while the engine is running and a threshold that indicates that the effectiveness of the EGR cooler is reduced below a lower threshold level. If such a level has not been reached at 930 the method continues to 932 to continue engine operation. Otherwise, if such a level or frequency has been reached at 930, the method continues to 934 to shut down the engine and indicate that manual cleaning operation of the EGR cooler is required. A system and method for executing a manual cleaning operation of the EGR cooler is shown at
In one embodiment, the EGR cooler may be cleaned by uncoupling the EGR cooler from the exhaust system (or a port is opened to provide access). A cleaning solution may be added to the interior of the EGR cooler, and allowed to soak. The now-soiled solution is drained and the process is repeated until a desired level of cleanliness is achieved. Suitable cleaning solutions may include low-foaming salts, such as tri-sodium phosphate, which are commercially available. In another embodiment, the EGR cooler may be cleaned via a cleaning system while coupled to the engine.
Specifically,
At 1112, the method includes turning the pump to drain mode and draining the cleaning solution from the EGR cooler via the suction hose and drain hose (e.g., drain hose 1006 in
The EGR cooler may experience a highest amount of thermal stress at the inlet section of the EGR cooler, proximate to the gas inlet of the EGR cooler (e.g., where hot exhaust gases enter the EGR cooler). The cooling tubes and fins at the most upstream section(s) of the EGR cooler experience the hottest temperatures and thus may experience degradation at this section of the EGR cooler. As the exhaust gases travel through the EGR cooler, heat is transferred to the heat transfer medium flowing through the cooling tubes of the EGR cooler (e.g., water or coolant). Thus, the material temperature of the EGR cooler tubes and fins coupled to the cooling tubes decreases at a downstream end of the EGR cooler. In order to reduce an amount of thermal stress on tubes of the EGR cooler, the EGR cooler may include different fin densities and/or different material types for one or more sections of the EGR cooler, as described below with reference to
Each section includes a separate plurality of fins (e.g., heat transfer fins). The fins may reduce a temperature of exhaust gases flowing past the cooling tubes by directing thermal energy away from the exhaust gases and toward the cooling tubes. The first section includes a first fin group 1212, the second section includes a second fin group 1214, the third section includes a third fin group 1216, the fourth section includes a fourth fin group 1218, the fifth section includes a fifth fin group 1220, and the sixth section includes a sixth fin group 1222. In the embodiment shown by
Additionally, in some embodiments, each fin may only be coupled to one cooling tube such that heat transfer between adjacent cooling tubes is reduced. Said another way, each cooling tube may have its own set of fins that do not contact any other cooling tube other than the one tube they are coupled to. In some embodiments, in the first section of the EGR cooler, nearest the inlet, each cooling tube may have its own set of fins that only contact that one cooling tube and not any other cooling tube of the first section. In this way, fins may not be coupled to and contact more than one cooling tube. This may be referred to as a unitary fin arrangement that reduces heat transfer between tubes, especially in the most upstream section of the EGR cooler, proximate to the gas inlet.
In some embodiments (such as that shown by
In some embodiments, one or more sections of the EGR cooler may include tubes and/or fins formed of a different material than one or more other sections. For example, sections closer to the inlet end of the EGR cooler may include tubes and fins formed of a material having a lower coefficient of thermal expansion (CTE) than sections closer to the outlet end of the EGR cooler. In one example, tubes and fins in sections closer to the inlet end may be formed from a first metal (e.g., 409L ferritic stainless steel), and tubes and fins in sections closer to the outlet end may be formed from a second metal (e.g., 316L stainless steel), with a CTE of the first metal being less than a CTE of the second metal. For example, the first metal may have a CTE that is less than 13 cm/cm/° C.×10−6. In another example, the first metal may have a CTE that is less than 12 cm/cm/° C.×10−6. In yet another example, the CTE of the first metal may be in a range of 10 to 13 cm/cm/° C.×10−6. In still another example, the CTE of the first metal may be in a range of 10.5 to 12.4 cm/cm/° C.×10−6. The second metal may have a CTE that is greater than 15 cm/cm/° C.×10−6. In another example, the CTE of the second metal may be in range of 15.5 to 19.5 cm/cm/° C.×10−6. In some embodiments, the CTE of the first metal may be approximately 35%-40% less than the CTE of the second metal. In the example shown by
By configuring the sections as described above, an amount of thermal stress on tubes and fins within each section may be decreased. For example, hot exhaust gases flowing into the inlet of the EGR cooler have a greater amount of thermal energy than exhaust gases flowing out of the outlet of the EGR cooler. Each section of the EGR cooler reduces the thermal energy of the exhaust gases (e.g., via the tubes and fins) as the exhaust gases flow past the cooling tubes and fins (e.g., around exterior surfaces of each tube and fin). As an example, the first section reduces the temperature of the exhaust gases by a first amount, the second section reduces the temperature of the exhaust gases by a second amount, and so forth. As a result, exhaust gases flowing from the first section to the second section are at a higher temperature than exhaust gases flowing from the second section to the third section, exhaust gases flowing from the third section to the fourth section are at a higher temperature than exhaust gases flowing from the fourth section to the fifth section, and so forth.
In some embodiments, the tubes of each of the sections may be formed of a first material (e.g., the first metal or second metal as described above), and the fins of one or more sections may be formed of a different material than one or more other sections. For example, each tube of the first through sixth sections may be formed of a first metal having a low CTE (e.g., 409L stainless steel). However, sections nearest to the inlet end (e.g., the first section and/or second section) may include fins formed of the first metal and sections nearest to the outlet end (e.g., the third through sixth sections) may include fins formed of a second metal different than the first metal and having a higher CTE (e.g., 316L stainless steel). In alternate embodiments, each tube of each section may be formed of a first material, and each fin within sections nearest to the inlet end may be formed of a second material having a low CTE while fins within sections nearest to the outlet end are formed of a third material having a higher CTE, with the second material and third material being different than the first material. Other combinations of materials are possible. However, in each embodiment, a CTE of a material forming fins in sections nearest to the inlet end is lower than a CTE of a material forming fins in each other section.
By configuring the sections nearest to the inlet end to include tubes and/or fins formed of a material with a lower CTE, an amount of expansion of the fins and/or tubes in response to the relatively high temperature of the exhaust gases may be reduced. In one example, the fins and/or tubes may be configured with different materials such that an expansion amount of fins and/or tubes in sections nearest to the inlet end (e.g., at a first, higher temperature) is approximately a same amount as an expansion amount of fins and/or tubes in sections nearest to the outlet end (e.g., at a second, lower temperature). In this way, the fins and/or tubes within the various sections of the EGR cooler may expand and/or contract at approximately a same rate, and an amount of thermal stress on the fins and/or tubes may be decreased.
As described above, in some examples (as shown by
As described above with reference to
A first embodiment of an EGR cooler includes a first section arranged proximate to an exhaust gas inlet of the EGR cooler. The first section includes a first plurality of tubes and a first plurality of fins coupled to the first plurality of tubes. At least one of the first plurality of tubes and the first plurality of fins are comprised of a first material that has a first CTE. The EGR cooler additionally includes a second section arranged downstream of the first section. The second section includes a second plurality of tubes and a second plurality of fins coupled to the second plurality of tubes. The second plurality of tubes and the second plurality of fins are comprised of a second material that has a second CTE, and the second CTE is greater than the first CTE.
The second section may be positioned downstream of the first section relative to a direction of exhaust gas flow through the EGR cooler, from the exhaust gas inlet to an exhaust gas outlet of the EGR cooler. Both the first plurality of tubes and the first plurality of fins may be comprised of the first material. The first plurality of tubes may be arranged into a single bundle group and the second plurality of tubes may be arranged into a plurality of bundle groups. The single bundle group and plurality of bundle groups are separated from one another via an exterior baffle.
Each tube of the first plurality of tubes may be coupled to a same set of tube sheets at ends of each tube. Each tube of each bundle group of the plural of bundle groups is coupled to a same set of tube sheets at ends of each tube, where each bundle group of the plurality of bundle groups has a different set of tube sheets than other bundle groups of the plurality of bundle groups. Each fin of the first plurality of fins may be coupled to only one tube of the first plurality of tubes. A fin density of the first plurality of fins is less than a fin density of the second plurality of fins.
A second embodiment of an EGR cooler includes an exhaust gas inlet and exhaust gas outlet spaced from the exhaust gas inlet. A plurality of cooling tubes are disposed between the exhaust gas inlet and exhaust gas outlet. A plurality of fins are coupled to the plurality of cooling tubes, and a portion of at least one of the plurality of cooling tubes and the plurality of fins are comprised of a first material that has a CTE that is less than 13 cm/cm/° C.×10−6. The portion is positioned adjacent to the exhaust gas inlet.
The plurality of cooling tubes may include a first group of cooling tubes positioned adjacent to the exhaust gas inlet. The plurality of fins may include a first group of fins coupled to the first group of cooling tubes. At least one of the first group of cooling tubes and the first group of fins is comprised of the first material.
The plurality of cooling tubes may additionally include a second group of cooling tubes positioned downstream from the first group of cooling tubes, relative to a direction of exhaust gas flow through the EGR cooler. The plurality of fins may include a second group of fins coupled to the second group of cooling tubes. The second group of cooling tubes and the second group of fins are comprised of a second material that has a CTE that is greater than 15 cm/cm/° C.×10−6. Both the first group of cooling tubes and the first group of fins are comprised of the first material.
The plurality of cooling tubes may be grouped into a plurality of bundle groups of multiple cooling tubes, and the plurality of bundle groups includes a first bundle group comprising the first group of cooling tubes and first group of fins. Each bundle group of the plurality of bundle groups may be separated from adjacent bundle groups of the plurality of bundle groups via an exterior baffle. The first bundle group is a most upstream bundle group positioned upstream of remaining bundle groups of the plurality of bundle groups. Fins and cooling tubes of the remaining bundle groups have a second CTE that is greater than 15 cm/cm/° C.×10−6.
Each fin of the plurality of fins may be coupled to a single cooling tube of the plurality of cooling tubes and is not in contact with any other cooling tube of the plurality of cooling tubes. A fin density of the plurality of fins may be smaller proximate to an interior sidewall of a housing of the EGR cooler than at a center of the EGR cooler. In one example, the fin density proximate to the exhaust gas inlet and the interior sidewall is less than 50% of a fin density proximate to the exhaust gas outlet.
A third embodiment of an EGR cooler includes an exhaust gas inlet and an exhaust gas outlet spaced from the exhaust gas inlet. A plurality of bundle groups is disposed between the exhaust gas inlet and exhaust gas outlet. Each bundle group of the plurality of bundle groups includes multiple cooling tubes. The plurality of bundle groups includes a first set of bundle groups positioned adjacent to the exhaust gas inlet and a second set of bundle groups positioned downstream of the first set of bundle groups. Cooling tubes of the first set of bundle groups are comprised of a first material having a first CTE and cooling tubes of the second set of bundle groups are comprised of a second material having a second CTE. The second CTE is greater than the first CTE.
A first set of fins may be coupled to cooling tubes of the first set of bundle groups and a second set of fins may be coupled to cooling tubes of the second set of bundle groups. The first set of fins are comprised of the first material and the second set of fins are comprised of the second material.
Although embodiments are described herein in reference to EGR coolers, in another aspect any of the embodiments of the coolers described herein may be used for cooling gases in other contexts, in vehicles or other engine systems or otherwise (e.g., a charge air cooler for cooling compressed intake air). Thus, in one embodiment, a gas cooler (e.g., for an engine system) includes a first section and a second section. The first section is arranged proximate to a gas inlet of the EGR cooler and includes a first plurality of tubes and a first plurality of fins coupled to the first plurality of tubes, where at least one of the first plurality of tubes and the first plurality of fins are comprised of a first material that has a first CTE. The second section is arranged downstream of the first section and includes a second plurality of tubes and a second plurality of fins coupled to the second plurality of tubes, where the second plurality of tubes and the second plurality of fins are comprised of a second material that has a second CTE; the second CTE is greater than the first CTE. In other embodiments, the gas cooler additionally or alternatively includes one or more other parts, features, or configurations as set forth herein.
In another embodiment, a gas cooler includes a gas inlet and a gas outlet spaced from the gas inlet, e.g., the cooler has a housing or body that defines an interior, an inlet, and an outlet. The gas cooler further includes a plurality of cooling tubes disposed between the gas inlet and gas outlet, e.g., within the interior of the housing or body. The gas cooler further includes a plurality of fins coupled to the plurality of cooling tubes, where a portion of at least one of the plurality of cooling tubes and the plurality of fins are comprised of a first material that has a CTE that is less than 13 cm/cm/° C.×10-6, the portion positioned adjacent to the gas inlet. In other embodiments, the gas cooler additionally or alternatively includes one or more other parts, features, or configurations as set forth herein.
In another embodiment, a gas cooler includes a gas inlet and a gas outlet spaced from the gas inlet, e.g., the cooler has a housing or body that defines an interior, an inlet, and an outlet. The cooler further includes a plurality of bundle groups disposed between the gas inlet and gas outlet (e.g., inside the interior of the housing or body), each bundle group of the plurality of bundle groups including multiple cooling tubes, the plurality of bundle groups including a first set of bundle groups positioned adjacent to the gas inlet and a second set of bundle groups positioned downstream of the first set of bundle groups. Cooling tubes of the first set of bundle groups are comprised of a first material having a first CTE and cooling tubes of the second set of bundle groups are comprised of a second material having a second CTE. The second CTE is greater than the first CTE. In other embodiments, the gas cooler additionally or alternatively includes one or more other parts, features, or configurations as set forth herein.
As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the invention do not exclude the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. The terms “including” and “in which” are used as the plain-language equivalents of the respective terms “comprising” and “wherein.” Moreover, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements or a particular positional order on their objects.
The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described actions, operations and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the engine control system, where the described actions are carried out by executing the instructions in a system including the various engine hardware components in combination with the electronic controller.
This written description uses examples to disclose the invention, including the best mode, and also to enable a person of ordinary skill in the relevant art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
This present application is a continuation-in-part of U.S. Non-Provisional patent application Ser. No. 15/086,618, entitled “EXHAUST GAS RECIRCULATION SYSTEM AND METHOD,” filed on Mar. 31, 2016. U.S. Non-Provisional patent application Ser. No. 15/086,618 claims priority to U.S. Provisional Application No. 62/141,624, entitled “EXHAUST GAS RECIRCULATION SYSTEM AND METHOD,” filed Apr. 1, 2015, and is a continuation-in-part of U.S. application Ser. No. 13/548,163, entitled, “SYSTEMS AND METHODS FOR A COOLING FLUID CIRCUIT,” filed Jul. 12, 2012, now U.S. Pat. No. 9,309,801. The entire contents of each of the above-identified applications are hereby incorporated by reference for all purposes.
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| Number | Date | Country | |
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| Child | 15428318 | US | |
| Parent | 13548163 | Jul 2012 | US |
| Child | 15086618 | US |
