Patent Publication Number: US-10330054-B2

Title: Systems and method for an exhaust gas recirculation cooler coupled to a cylinder head

Description:
FIELD 
     The present description relates generally to methods and systems for a cooler for an exhaust gas recirculation (EGR) system of an internal combustion engine. 
     BACKGROUND/SUMMARY 
     Internal combustion engines, such as a gasoline engine, produce a variety of waste gases that are expelled from the cylinders through the cylinder head during operation. Some of these gases may be expelled into the atmosphere while some may be recycled by the engine through the use of an exhaust gas recirculation (EGR) system. An EGR system can reduce nitrogen oxide (NO x ) emissions to the atmosphere by allowing the engine to replace a portion of its intake gases with exhaust gases. Allowing the EGR system to control the ratio of these gases within the cylinders can effectively lower the temperatures of the cylinders by limiting the amount of combustible intake gas available during each combustion cycle. The reduction in cylinder temperatures provided by an EGR system simultaneously reduces NO x  generation because NO x  forms mainly within a narrow temperature range near peak cylinder temperatures. One problem that arises with such systems is that the gas from the EGR system is relatively hot compared to the intake gas. Hot exhaust gases routed back into the cylinder can lead to degradation of valves, less efficient combustion, and increased cylinder temperatures, thereby cancelling some of the benefits gained through the implementation of the EGR system. 
     One example of a solution to the problem of recycling hot exhaust gases is to integrate a cooler system within the EGR system. An EGR cooler helps to reduce the temperature of the recycled exhaust gases before they are released into the intake manifold (and in turn, the cylinders). EGR coolers are often comprised of a unit with a series of inlets and outlets for both input and output of EGR gases and coolant. The EGR cooler may be mounted to a surface within the engine compartment, in close proximity to the engine. EGR coolers may have a number of fittings used to couple with tubes and/or pipes for coolant and gas exchange. 
     However, the inventors herein have recognized potential issues with such systems. As one example, the fittings of an EGR cooler are often subjected to intense temperatures and involve extended contact with fluids. As a consequence, the materials used to construct fittings to fulfill these requirements are often exotic and/or expensive. In addition, the assembly and repair of the fittings can also be time-consuming and increase labors costs. EGR cooler fittings may develop leaks and because the coolers are often located near several high-temperature areas of the engine (such as the cylinder head and exhaust manifold) a leak in the fittings can result in engine degradation. The coolers and their connections also tend to be bulky and increase the overall volume occupied within the engine compartment. 
     In one example, the issues described above may be addressed by an exhaust gas recirculation (EGR) system, comprising: an EGR cooler module including a body and an EGR inlet port, EGR outlet port, and coolant inlet port, all extending from the body and arranged in parallel with one another and at a same, first side of a cylinder head, where the EGR inlet port and coolant inlet port are directly coupled to the first side of the cylinder head. In this way, the EGR cooler module may interface directly with coolant and gas passages within the cylinder head. In one example, the bolts that mount the EGR cooler module to the surface of the cylinder head also compress a gasket that seals the connection between the surfaces. The result is that the EGR cooler module has a compact form with fewer fittings. 
     It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic of a first embodiment of an engine system including an EGR system with an EGR cooler module mounted to a cylinder head. 
         FIG. 2  shows an exploded view of a first embodiment of an EGR system including a cylinder head and EGR cooler module mounted to the cylinder head. 
         FIG. 3  shows a schematic of a second embodiment of an engine system including an EGR system with an EGR cooler module mounted to a cylinder head. 
         FIG. 4  shows a perspective view of a cylinder head of a second embodiment of an EGR system. 
         FIG. 5  shows a perspective view of the cylinder head and an EGR cooler module mounted to the cylinder head of the second embodiment of the EGR system. 
         FIG. 6  shows an additional perspective view of the second embodiment of the EGR system including the EGR cooler module with the cylinder head shown in cross-section. 
         FIG. 7  shows a flow chart of a method for flowing exhaust gas and coolant through a cylinder head and EGR cooler mounted directly to a side of the cylinder head. 
     
    
    
       FIG. 2  and  FIGS. 4-6  are shown approximately to scale. 
     DETAILED DESCRIPTION 
     The following description relates to systems and methods for an exhaust gas recirculation (EGR) system including an EGR cooler module directly mounted to a cylinder head. An EGR system of an engine system may include a cylinder head, an EGR cooler module mounted to the cylinder head, and a plurality of coolant and gas passages internal to the cylinder head, as shown in  FIG. 1 . The cylinder head of the EGR system may include a plurality of mounting surfaces configured such that the EGR cooler module may be directly coupled to the cylinder head, as shown by  FIG. 2  and  FIGS. 5-6 . The cylinder head may include a plurality of coolant ports and gas ports formed by the internal passages of the cylinder head, as shown by  FIGS. 1-6 . The EGR cooler module may include a plurality of gas ports and coolant ports configured to interface directly with the corresponding ports of the cylinder head when the EGR cooler module is directly coupled to the cylinder head, as shown by  FIGS. 1-6 . The cylinder head of the EGR system may optionally include additional passages for routing gas and coolant from the EGR cooler module back through the cylinder head, as shown in the embodiment of  FIGS. 1-2 . The EGR system may optionally include coolant and gas passages external to the cylinder head for the EGR cooler module to return coolant and gas to the engine system, as shown in the embodiment presented at  FIGS. 3-6 . Additionally,  FIG. 7  presents a method for flowing coolant and exhaust gas through a cylinder head and EGR cooler module directly coupled to the cylinder head, such as the cylinder head and EGR cooler module of one of the embodiments shown in  FIGS. 1-2  and/or  FIGS. 3-6 . In this way, the EGR cooler module of the EGR system may interface with the cylinder head to receive coolant and exhaust gas and may return gas and coolant to the engine system via passages internal to the cylinder head or passages external to the cylinder head. 
     Similar components in  FIGS. 1-7  are labeled similarly and may only be explained once below and not re-introduced with reference to each figure. 
       FIG. 1  shows a schematic including an engine system  100 , as well as an EGR system  101 . The engine system  100  includes a multi-cylinder internal combustion engine  102 . Engine  102  may include a plurality of cylinders (e.g., combustion chambers) which may be capped on the top by cylinder head  134 . In the example shown in  FIG. 1 , engine  102  includes three cylinders:  120 ,  122 , and  124 . It will be appreciated that the cylinders may share a single engine block (not shown) and a crankcase (not shown), where engine block is coupled to and below the cylinder head. The engine system  100  also includes an intake manifold  106 , an integrated exhaust manifold (IEM)  132 , and a radiator  162 . 
       FIG. 1  is a schematic view showing the flow of gas and coolant between components of the engine system  100 . Therefore, the passages and components are not shown to scale and the relative positioning, size, and number of passages may vary in physical embodiments (e.g., the embodiment shown by  FIG. 2 ). 
     While engine  102  is depicted as an inline-three engine with three cylinders, it will be appreciated that other embodiments may include a different number of cylinders and arrangement of cylinders, such as V-6, I-4, I-6, V-12, opposed 4, and other engine types. 
     Each cylinder may receive intake air from intake manifold  106  via intake passage  104 . Intake manifold  106  may contain cylinder intake passages (e.g., runners)  108 ,  110 , and  112  coupled to the cylinders via intake ports  114 ,  116 , and  118 , respectively. Each intake port may supply air and/or fuel to the cylinder it is coupled to for combustion. Each intake port can selectively communicate with the cylinder via one or more intake valves. Cylinders  120 ,  122 , and  124  are shown in  FIG. 1  with one intake port each, with each intake port including an intake valve disposed within. For example, cylinder  120  has one intake port  114 , cylinder  122  has one intake port  116 , and cylinder  124  has one intake port  118 . Other embodiments may include a different number of intake ports and/or intake valves per cylinder (e.g., two, three, etc.). 
     Each cylinder (e.g., cylinders  120 ,  122 , and  124 ) may receive fuel from fuel injectors (not shown) coupled directly to the cylinder, as direct injectors, and/or from injectors coupled to the intake manifold  106 , as port injectors. Further, air charges within each cylinder may be ignited via spark from respective spark plugs (not shown). In other embodiments, the cylinders of engine  102  may be operated in a compression ignition mode, with or without an ignition spark. 
     Intake passage  104  may include an air intake throttle  109 . The position of throttle  109  can be adjusted via a throttle actuator (not shown) communicatively coupled to a controller (not shown). By modulating air intake throttle  109 , an amount of fresh air may be inducted from the atmosphere into engine  102 , delivered to the engine cylinders via intake manifold  106 . A portion of the intake air may be compressed by a compressor (not shown) and/or cooled by a charge air cooler (not shown). 
     Each cylinder may exhaust combustion gases via one or more exhaust valves into exhaust ports (e.g., cylinder exhaust ports) coupled thereto. Cylinders  120 ,  122 , and  124  are shown in  FIG. 1  with one exhaust port each, each including an exhaust valve disposed therein for exhausting combustion gases from a corresponding cylinder. For example, cylinder  120  has one exhaust port  126 , cylinder  122  has one exhaust port  128 , and cylinder  124  has one exhaust port  130 . Other embodiments may include a different number of exhaust ports and/or exhaust valves per cylinder (e.g., two, three, etc.). 
     Each cylinder may be coupled to a manifold exhaust port  144  for exhausting combustion gases. In the example of  FIG. 1 , an internal exhaust junction  142  internal to the IEM  132  receives exhaust gases from cylinder  120  via exhaust port  126  coupled to runner (e.g., exhaust runner)  136 , exhaust gases from cylinder  122  via exhaust port  128  coupled to runner  138 , and exhaust gases from cylinder  124  via exhaust port  130  coupled to runner  140 . Exhaust gases entering the internal exhaust junction  142  may mix and converge. Exhaust gases travel from the internal exhaust junction  142  through manifold exhaust passage  145  to the manifold exhaust port  144 . Therefrom, the exhaust gases are directed via an external exhaust passage  146  (external to the IEM  132  and cylinder head  134 ) to other engine components (such as an emission control device and/or turbine of a turbocharger, not shown). It will be noted that in the example of  FIG. 1 , the runners  136 ,  138 , and  140 , as well as the internal exhaust junction  142 , manifold exhaust passage  145 , and manifold exhaust port  144 , are integrated within the cylinder head  134  collectively as the integrated exhaust manifold (IEM)  132 . In other words, the components of the IEM  132  are internal to the cylinder head  134 . Alternate embodiments may contain a different number and/or arrangement of runners, manifold exhaust ports, internal exhaust junctions, and/or internal exhaust passages. 
     As described above, each cylinder comprises one intake valve (disposed within an intake port) and one exhaust valve (disposed within an exhaust port). Herein, each intake valve is actuatable between an open position allowing intake air into a respective cylinder and a closed position substantially blocking intake air from the respective cylinder. Intake valves within intake ports  114 ,  116 , and  118  are actuated by a common intake camshaft (not shown). The intake camshaft includes a plurality of intake cams (not shown) configured to control the opening and closing of the intake valves. Each intake valve may be controlled by one or more intake cams, which will be described further below. In some embodiments, one or more additional intake cams may be included to control the intake valves. Further still, intake actuator systems may enable the control of intake valves. 
     Each exhaust valve is actuatable between an open position allowing exhaust gas out of a respective cylinder and a closed position substantially retaining gas within the respective cylinder. Exhaust valves within exhaust ports  126 ,  128 , and  130  are actuated by a common exhaust camshaft (not shown). Exhaust camshaft includes a plurality of exhaust cams (not shown) configured to control the opening and closing of the exhaust valves. Each exhaust valve may be controlled by one or more exhaust cams, which will be described further below. In some embodiments, one or more additional exhaust cams may be included to control the exhaust valves. Further, exhaust actuator systems may enable the control of exhaust valves. 
     Intake valve actuator systems and exhaust valve actuator systems may further include push rods, rocker arms, tappets, etc. (not shown). Such devices and features may control actuation of the intake valves and the exhaust valves by converting rotational motion of the cams into translational motion of the valves. In other examples, the valves can be actuated via additional cam lobe profiles on the camshafts, where the cam lobe profiles between the different valves may provide varying cam lift height, cam duration, and/or cam timing. However, alternative camshaft (overhead and/or pushrod) arrangements could be used, if desired. Further, in some examples, cylinders  120 ,  122 , and  124  may each have more than one exhaust valve and/or intake valve. In still other examples, exhaust valves and intake valves may be actuated by a common camshaft. However, in alternate embodiments, at least one of the intake valves and/or exhaust valves may be actuated by its own independent camshaft or other device. 
     Surrounding the cylinders  120 ,  122 , and  124 , as well as the IEM  132  and its components (e.g., runners, junctions, etc.) within the cylinder head  134  are a plurality of coolant passages  160 . The coolant passages  160  are connected to one or more coolant inlet and outlet ports (e.g., such as first engine coolant inlet port  166 , first engine coolant outlet port  167 , second engine coolant inlet port  169 , and second engine coolant outlet port  170 ) to facilitate the circulation of coolant throughout the cylinder head  134  and around the IEM  132 . 
     Upon entering the cylinder head  134  through a coolant inlet (e.g., first engine coolant inlet port  166 ) the coolant passes through the plurality of coolant passages (e.g., coolant passages  160 ) within the cylinder head  134  and receives heat from the components of the cylinder head  134  and IEM  132 . The coolant exits the cylinder head  134  through one or more coolant outlets (e.g., first engine coolant outlet port  167 ). The coolant then passes through an EGR cooler module  148  directly coupled to a side of the cylinder head  134 , returns to the cylinder head  134  through a second coolant inlet port (e.g., second engine coolant inlet port  169 ), exits the cylinder head  134  again through a second coolant outlet port (e.g., second engine coolant outlet port  170 ) and enters the radiator  162  in order to reduce its thermal energy before re-entering the cylinder head  134  at the first inlet port (e.g., first engine coolant inlet port  166 ). In the embodiment of  FIG. 1 , second engine coolant outlet port  170  is coupled to the radiator  162  via second external coolant passage  172 . The radiator  162  is also coupled to first engine coolant inlet port  166  of the cylinder head  134  via first external coolant passage  164 . The radiator  162  is utilized to reduce the thermal energy of the coolant. In alternate embodiments the radiator  162  may be coupled to additional devices (e.g., fans) to remove thermal energy from the coolant. It may also optionally or additionally circulate coolant through one or more additional devices (e.g., pumps). 
     The EGR cooler module  148  is directly coupled (e.g., directly mounted without any intervening components separating the EGR cooler module and cylinder head) to the cylinder head  134  through the use of bolts or other mechanical fixation elements (as described in the discussion of  FIG. 2  below). The EGR cooler module  148  contains a plurality of ports at an exterior of the EGR cooler module  148 , with each port capable of fluidic communication with a corresponding port on an exterior of the cylinder head (as shown by  FIG. 2 ). 
     A first internal passage  150  of the cylinder head  134  is internal to the cylinder head  134  and routes exhaust gas through the cylinder head  134 . In the schematic of  FIG. 1 , the first internal passage  150  is in fluidic communication with manifold exhaust passage  145  downstream of internal exhaust junction  142  where exhaust from all of the cylinders converges (e.g., cylinders  120 ,  122 ,  124 ). The first internal passage  150  is a peripheral passage to manifold exhaust passage  145 . In other words, first internal passage  150  receives a portion of the exhaust gases flowing through manifold exhaust passage  145 . In alternate embodiments, the first internal passage  150  may receive exhaust gases from upstream of internal exhaust junction  142  and may be a peripheral passage (as described above) to one or more exhaust runners (such as exhaust runners  136 ,  138 , and  140 ) of one or more cylinders (such as cylinders  120 ,  122 , and  124 ). In these alternate embodiments, the first internal passage  150  may receive a portion of exhaust gases from one or more runners of one or more cylinders but it does not receive exhaust gases downstream of a junction at which exhaust from all of the cylinders converges (e.g., internal exhaust junction  142 ). In this way, the first internal passage  150  may receive exhaust gases expelled from one or more cylinders of the engine. 
     The first internal passage  150  routes exhaust gases through the cylinder head  134  from the manifold exhaust passage  145  (which may be referred to herein as an exhaust manifold) to a first engine EGR outlet port  151 . The first engine EGR outlet port  151  is in fluidic communication with an EGR inlet port  153  of the cooler module  148  (as described in the discussion of  FIG. 2  below). The EGR inlet port  153  may hereafter be referred to as module EGR inlet port  153 . From the module EGR inlet port  153 , exhaust gas is routed through and cooled by the EGR cooler module  148 . Cooled exhaust gases from the EGR cooler may then exit the EGR cooler via an EGR outlet port (e.g., module EGR outlet port)  157 . A second internal passage  152  of the cylinder head  134  is internal to the cylinder head  134  and routes cooled exhaust gases from a first engine EGR inlet port  155  to a second engine EGR outlet port  154 . The first engine EGR inlet port  155  is in fluidic communication with the EGR outlet port  157  of the EGR cooler module  148 . 
     The second engine EGR outlet port  154  is in fluidic communication with an EGR passage (which may hereafter be referred to as an external EGR passage)  161  arranged external to the cylinder head  134  (e.g., not formed within the cylinder head). An EGR valve  156  is coupled inline with the external EGR passage  161 . The external EGR passage  161  is also in fluidic communication with an intake EGR inlet port  163  of the intake manifold  106 . The EGR valve  156  may be actuated by an actuator (not shown) to control the flow of gases from the second engine EGR outlet port  154 , through the external EGR passage  161 , to the intake EGR inlet port  163 , and into the intake manifold  106 . 
     In the embodiment of  FIG. 1 , the intake EGR inlet port  163  is upstream of the cylinder intake passages  108 ,  110 , and  112  within the intake manifold  106 . Alternate embodiments may exist in which the intake EGR inlet port is not upstream of all of the cylinder intake passages and may be downstream of one or more of the cylinder intake passages. Alternate embodiments may additionally include a plurality of external EGR passages (similar to external EGR passage  161 ) coupling the second engine EGR outlet port to one or more intake EGR inlet ports (similar to intake EGR inlet port  163 ) at the intake manifold and/or one or more cylinder intake passages. 
     The EGR cooler module  148  contains a plurality of passages (not shown) to facilitate the transfer of heat from the exhaust gas received through the module EGR inlet port  153  to a supply of coolant within the EGR cooler module  148 . The passages within the EGR cooler module  148  containing exhaust gases and the passages within the EGR cooler module  148  containing coolant are separated and not in fluidic communication with each other. However, the gas passages and coolant passages are proximate to each other and may be simultaneously proximate to a material with high thermal conductivity (e.g., metal). Heat may transfer from the gas within the exhaust gas passages through a proximate thermally conductive material and into the coolant. In this way, the EGR cooler module  148  cools the gas exiting the module such that the gas entering the module is at a higher temperature than the gas exiting the module. 
     The coolant within the EGR cooler module  148  is supplied through a coolant inlet port (which may hereafter be referred to as module coolant inlet port)  165  of the EGR cooler module  148 . The module coolant inlet port  165  is in fluidic communication with a third internal passage  158  of the cylinder head  134 . The third internal passage  158  is internal to the cylinder head  134  and routes through the cylinder head  134 . 
     The third internal passage  158  is in fluidic communication with the plurality of passages  160  internal to the cylinder head  134  that surround the cylinders, runners, and other components internal to the cylinder head  134 . These passages  160  are fluidically isolated from the cylinders, runners, and other components that they surround but are not fluidically isolated from each other (e.g., coolant may flow within the coolant passages but does not flow into other components of the cylinder head). In other words, the passages are separated from the cylinders, runners, and other components by interior walls of the cylinder head. 
     Coolant is routed through the passages from the radiator  162 . The radiator  162  is coupled to the first exterior coolant passage  164  which is in fluidic communication with the first engine coolant inlet port  166 . The first engine coolant inlet port  166  is coupled to the passages  160  such that coolant flows from the radiator  162 , through the first exterior coolant passage  164 , through the first engine coolant inlet port  166 , and into the plurality of passages  160  within the cylinder head. 
     The coolant entering the plurality of passages via the radiator  162  is routed through the third internal passage  158  and passes through a first engine coolant outlet port  167 . The first engine coolant outlet port  167  is coupled (e.g., directly coupled) to the module coolant inlet port  165  and is in fluidic communication with the plurality of coolant passages (not shown) within the EGR cooler module  148 . In this way, the EGR cooler module  148  receives coolant from the radiator  162  via the passages (e.g., passages  160  and third internal passage  158 ) within the cylinder head  134 . 
     The plurality of coolant passages (not shown) within the EGR cooler module  148  return coolant to a module coolant outlet port  171  which is coupled (e.g., directly coupled) to the second engine coolant inlet port  169 . The coolant transfers from the module coolant outlet port  171  into the second engine coolant inlet port  169  and then into a fourth internal passage  168  of the cylinder head  134 . The fourth internal passage  168  is internal to (e.g., positioned within an interior of) the cylinder head  134  and formed by the interior walls of the cylinder head  134 . The fourth internal passage  168  routes coolant through the cylinder head  134  and to the second engine coolant outlet port  170 . The second engine coolant outlet port  170  is coupled to the second external coolant passage  172 . The second external coolant passage  172  is external to the cylinder head  134  and is coupled to (and in fluidic communication with) both the radiator and the second engine coolant outlet port  170 . In this arrangement, coolant may exit the EGR cooler module  148 , flow through the fourth internal passage  168 , and enter the radiator  162  via the second external coolant passage  172  coupled to the second engine coolant outlet port  170 . 
     In the schematic of the configuration of the engine system  100  as described above, the EGR cooler module  148  receives coolant via a direct coupling between the first engine coolant outlet port  167  and the module coolant inlet port  165 , and receives exhaust gas via a direct coupling between the first engine EGR outlet port  151  and the module EGR inlet port  153 . The proximate passages internal to the EGR cooler module  148  then transfer thermal energy away from the exhaust gas and into the coolant. The cooled exhaust gas exits the EGR cooler module  148  and enters the cylinder head  134  via first engine EGR inlet port  155  where it is routed through second internal passage  152  to the second engine EGR outlet port  154 . The flow of the cooled gas through external EGR passage  161  into the intake EGR inlet port  163  of the intake manifold  106  is controlled by the actuation of EGR valve  156 . 
     The coolant exits the EGR cooler module  148  through the module coolant outlet port  171  and enters the fourth internal passage  168  of the cylinder head  134  via a direct coupling between the module coolant outlet port  171  and the second engine coolant inlet port  169 . The coolant flows out of the fourth internal passage  168  via the second engine coolant outlet port  170  and into the second external coolant passage  172  coupled with radiator  162 . In this way, the EGR cooler module  148  uses coolant from an internal coolant passage of the cylinder head  134  and exhaust gas from an internal gas passage of the cylinder head to cool exhaust gases from the cylinders ( 120 ,  122 , and  124 ). It then routes the cooled gases into the intake manifold via another internal gas passage of the cylinder head and the coolant into the radiator via another internal coolant passage of the cylinder head. 
     By directly coupling coolant inlets/outlets and EGR inlets/outlets of the EGR cooler module to the corresponding coolant inlets/outlets and EGR inlets/outlets on the cylinder head, the EGR cooler module is able to receive and transmit EGR gas and coolant from the cylinder head without additional fittings. 
       FIG. 2  shows an exploded view of a first embodiment of an EGR system  201  including an EGR cooler module  248  (e.g., such as the EGR cooler module  148  shown by  FIG. 1 ) directly mounted to a first cylinder head surface  249  of a cylinder head  235  (e.g., such as the cylinder head  134  shown by  FIG. 1 ) in an arrangement similar to the configuration described above during the discussion of  FIG. 1 . The first cylinder head surface  249  may be on a single, first side of the cylinder head  235 . The EGR cooler module  248  includes a housing (e.g., housing body or body)  200 , a plurality of rigid pipes (e.g., pipes  202 ,  204 , and  206 ) and a plurality of flanges (e.g., flanges  214  and  216 ). The housing  200  contains a plurality of internal cooling tubes (for flowing coolant) and internal gas passages (for flowing exhaust gas) therein. The housing, rigid pipes, and flanges of the EGR cooler module  248  may be constructed of a material (e.g., metal) resistant to wear by corrosion and/or high temperatures associated with engine fluids and gases. The housing, rigid pipes, flanges, and other components of the EGR cooler module may be formed together (e.g., molded) as one piece and/or may be fused together (e.g., welded). 
     In the example of the embodiment of the EGR cooler module  248  shown in  FIG. 2 , the housing  200  of the EGR cooler module  248  is formed such that the shape of the EGR cooler module  248  is approximately a rectangular parallelepiped. The housing  200  possesses an outward surface (which may hereafter be referred to as outward module surface)  252  that is parallel to and faces away from the first cylinder head surface  249  of the cylinder head  235  when the EGR cooler module  248  is mounted to the cylinder head  235  (as described below). The outward module surface  252  is joined to a plurality of perpendicular module surfaces (e.g., surfaces  253 ,  254 ,  255 , and  256 ) which are arranged perpendicular to the outward module surface  252 . The perpendicular module surfaces are joined to an inward module surface  257  (e.g., the surface facing the first cylinder head surface  249 ) which is arranged parallel to (and opposite from) the outward module surface  252 . In the example of the embodiment of the EGR cooler module  248  shown by  FIG. 2 , the perpendicular module surfaces  253 ,  254 , and  255  are planar (e.g., flat) while the perpendicular module surface  256  possesses a curve in the direction of the interior of the EGR cooler module  248 . The inward module surface  257  and outward module surface  252  are both planar (e.g., flat) and the outward module surface  252  is joined to the perpendicular surfaces with rounded edges while the inward module surface  257  is joined to the perpendicular surfaces without rounded edges. Alternate embodiments may exist in which the EGR cooler module possesses additional or fewer curves and/or has additional or fewer surfaces. 
     The EGR cooler module  248  of  FIG. 2  is directly coupled (e.g., formed as one piece or fused together) with three rigid pipes  202 ,  204 , and  206  (which may hereafter be referred to as first module pipe  202 , second module pipe  204 , and third module pipe  206 ). A first end (e.g., an end originating from the housing) of the first module pipe  202  is coupled to a housing coolant inlet  208  of the housing  200 . A first end (e.g., an end originating from the housing) of the second module pipe  204  is coupled to a housing coolant outlet  251  of the housing  200  and a first end (e.g., an end originating from the housing) of the third module pipe  206  is coupled to a housing EGR outlet  271  of the housing  200 . 
     The rigid pipes  202 ,  204 , and  206 , and the housing coolant inlet  208 , housing coolant outlet  251 , and housing EGR outlet  271  in the example of the embodiment shown in  FIG. 2  are arranged such that the inlets/outlets ( 208 ,  251 , and  271 ) and first ends (as described above) of the pipes ( 202 ,  204 , and  206 ) are positioned along the plurality of perpendicular module surfaces. The housing coolant inlet  208  (and the first end of the first module pipe  202 ) is positioned along the perpendicular module surface  253  (which may hereafter be referred to as first module perpendicular surface  253 ). The housing coolant outlet  251  and the housing EGR outlet  271  (as well as the first end of the second module pipe  204  and the first end of the third module pipe  206 ) are positioned along the perpendicular surface  254  (which may hereafter be referred to as second module perpendicular surface  254 ). 
     The flange  214  (which may be referred to as first module flange  214 ) is arranged parallel to the inward and outward module surfaces ( 257  and  252  respectively) and is joined with (e.g., formed from and/or welded to) the inward module surface  257 . The first module flange  214  projects outward from the housing  200  of the EGR cooler module  248  away from the perpendicular module surfaces  253  and  256 . Similarly, the flange  216  (which may be referred to as second module flange  216 ) is arranged parallel to the inward and outward module surfaces ( 257  and  252  respectively) and is joined with (e.g., formed from and/or welded to) the inward module surface  257 . The second module flange  216  projects outward from the housing  200  of the EGR cooler module  248  away from the perpendicular module surface  254 . Because the first module flange  214  and the second module flange  216  are simultaneously parallel to the inward and outward module surfaces ( 257  and  252  respectively), the first module flange  214  and the second module flange  216  are also parallel to each other. The first module flange  214  and second module flange  216  are also parallel to the first cylinder head surface  249  (and first side of the cylinder head). 
     The first module flange  214  includes a module coolant inlet port  218  (e.g., such as the module coolant inlet port  165  shown by  FIG. 1 ) coupled with a second end (e.g., an end not originating from the housing) of the first module pipe  202 . The module coolant inlet port  218  is in face-sharing contact with (and in fluidic communication with) a first engine coolant outlet port  267  (e.g., such as the first engine coolant outlet port  167  shown by  FIG. 1 ) on the first cylinder head surface  249  of the cylinder head. The first module flange  214  also includes a module EGR inlet port  220  (e.g., such as the module EGR inlet port  153  shown by  FIG. 1 ) in face-sharing contact with (and in fluidic communication with) a first engine EGR outlet port  247  (e.g., such as the first engine EGR outlet port  151  shown by  FIG. 1 ) on the first cylinder head surface  249  of the cylinder head. In this arrangement, the module coolant inlet port  218  facilitates the flow of coolant from the first engine coolant outlet port  267  into EGR cooler module  248  via the first module pipe  202  coupled with the housing coolant inlet  208 . The module EGR inlet port  220  facilitates the flow of EGR gas from the first engine EGR outlet port  247  directly into the EGR cooler module  248  via face-sharing contact between the module EGR inlet port  220  and the first engine EGR outlet port  247  (without the use of a rigid pipe). 
     The first module flange  214  also includes a plurality of eyelets (e.g., eyelets  224 ,  226 , and  228 ) sized and shaped to accommodate bolts. In the example of the embodiment of the first module flange  214  shown by  FIG. 2 , the first module flange  214  has three eyelets  224 ,  226 , and  228 . Alternate embodiments may exist in which the first module flange has a different number of eyelets (e.g., four, five, etc.). The eyelets are configured on the first module flange  214  in an arrangement that matches the arrangement of a plurality of mounting surfaces on the first cylinder head surface  249 . The eyelets  224 ,  226 , and  228  of the first module flange  214  in the embodiment shown in  FIG. 2  are configured to align with three mounting surfaces  230 ,  232 , and  234  when the first module flange  214  is placed flush against the mounting surfaces. The mounting surfaces  230 ,  232 , and  234  are formed such that they may accept the threaded ends of the bolts passing through eyelets  224 ,  226 , and  228 , thereby directly mounting the first module flange  214  to the first side of the cylinder head  235  and first cylinder head surface  249 . 
     The module coolant inlet port  218  and the module EGR inlet port  220  are arranged on the first module flange  214  such that when the first module flange  214  is bolted to the mounting surfaces  230 ,  232 , and  234  of the cylinder head  235 , the module coolant inlet port  218  is in face-sharing contact with the first engine coolant outlet port  267  and the module EGR inlet port  220  is in face-sharing contact with the first engine EGR outlet port  247 . One or more gaskets (not shown) may be secured between the first module flange  214  and the mounting surfaces ( 230 ,  232 , and  234 ) of the cylinder head  235  such that the gasket(s) permit fluidic communication without leakage between the module coolant inlet port  218  and the first engine coolant outlet port  267  as well as fluidic communication without leakage between the module EGR inlet port  220  and the first engine EGR outlet port  247 . The gasket(s) do not allow fluidic communication between the module coolant inlet port  218  and the module EGR inlet port  220 . The gasket(s) are formed from a material suitable for contact with corrosive and/or high-temperature fluids from the cylinder head  235  (e.g., a rubber-like material). 
     The second module flange  216  includes a module coolant outlet port  240  (e.g., such as module coolant outlet port  171  shown by  FIG. 1 ) coupled with a second end (e.g., an end not originating from the housing) of the second module pipe  204 . The module coolant outlet port  240  is in face-sharing contact with (and in fluidic communication with) a second engine coolant inlet port  269  (e.g., such as the second engine coolant inlet port  169  shown by  FIG. 1 ). The second module flange  216  also includes a module EGR outlet port  242  (e.g., such as module EGR outlet port  157  shown by  FIG. 1 ) coupled with a second end (e.g., an end not originating from the housing) of the third module pipe  206 . The module EGR outlet port  242  is in face-sharing contact with (and in fluidic communication with) a first engine EGR inlet port  259  (e.g., such as the first engine EGR inlet port  155  shown by  FIG. 1 ). In this arrangement, the module coolant outlet port  240  facilitates the flow of coolant from the EGR cooler module  248 , via the second module pipe  204  coupled with the housing coolant outlet  251 , and into the second engine coolant inlet port  269  of the cylinder head  235 . The module EGR outlet port  242  facilitates the flow of EGR gas from the EGR cooler module  248 , via the third module pipe  206  coupled with the housing EGR outlet  271 , and into the first engine EGR inlet port  259  of the cylinder head  235 . 
     The second module flange  216  also includes a plurality of eyelets (e.g., eyelets  244  and  246 ) sized and shaped to accommodate bolts. In the example of the embodiment of the first module flange  214  shown by  FIG. 2 , the second module flange  216  has two eyelets  244  and  246 . Alternate embodiments may exist in which the first module flange has a different number of eyelets (e.g., three, four, etc.). The eyelets are configured on the second module flange  216  in an arrangement that matches the arrangement of a plurality of mounting surfaces on the first cylinder head surface  249 . The eyelets  244  and  246  of the second module flange  216  in the embodiment shown in  FIG. 2  are configured to align with two mounting surfaces  258  and  260  when the second module flange  216  is placed flush against the mounting surfaces. The mounting surfaces  258  and  260  are formed such that they may accept the threaded ends of the bolts passing through eyelets  244  and  246 . 
     The module coolant outlet port  240  and the module EGR outlet port  242  are arranged on the second module flange  216  such that when the second module flange  216  is bolted to the mounting surfaces  258  and  260  of the cylinder head  235 , the module coolant outlet port  240  is in face-sharing contact with the second engine coolant inlet port  269  and the module EGR outlet port  242  is in face-sharing contact with the first engine EGR inlet port  259 . One or more gaskets (not shown) may be secured between the second module flange  216  and the mounting surfaces ( 258  and  260 ) of the cylinder head  235  such that the gasket(s) permit fluidic communication without leakage between the module coolant outlet port  240  and the second engine coolant inlet port  269 , as well as fluidic communication without leakage between the module EGR outlet port  242  and the first engine EGR inlet port  259 . The gasket(s) do not allow fluidic communication between the module coolant outlet port  240  and the module EGR outlet port  242 . The gasket(s) are formed from a material suitable for contact with corrosive and/or high-temperature fluids from the cylinder head  235  (e.g., a rubber-like material). 
     An alternate embodiment of the EGR cooler module  248  may include a single gasket spanning both the first and second flanges and providing all of the fluidic communications (and isolations) described above. 
     As described in the discussion of  FIG. 1 , the first engine EGR outlet port  247  is directly coupled to (e.g., formed by) a first internal passage (e.g., such as first internal passage  150  shown by  FIG. 1 ) of the cylinder head  235 , the first engine EGR inlet port  259  is directly coupled to (e.g., formed by) a second internal passage (e.g., such as second internal passage  152  shown by  FIG. 1 ) of the cylinder head  235 , the first engine coolant outlet port  267  is directly coupled to (e.g., formed by) a third internal passage (e.g., such as third internal passage  158  shown by  FIG. 1 ) of the cylinder head  235 , and the second engine coolant inlet port  269  is directly coupled to (e.g., formed by) a fourth internal passage (e.g., such as fourth internal passage  168  shown by  FIG. 1 ) of the cylinder head  235 . 
     By configuring the EGR cooler module  248  and cylinder head  235  in this way, the EGR cooler module  248  is able to receive coolant from the first engine coolant outlet port  267  of the cylinder head  235  via the module coolant inlet port  218  of the first module flange  214 . The coolant flows out of the first engine coolant outlet port  267  of the cylinder head  235  and through the module coolant inlet port  218  of the first module flange  214  into the first module pipe  202 . The first module pipe  202  then directs the flow of coolant towards the housing coolant inlet  208  of the EGR cooler module  248 . The EGR cooler module  248  is able to return coolant to the second engine coolant inlet port  269  of the cylinder head  235  via the module coolant outlet port  240  of the second module flange  216 . The coolant flows from the housing coolant outlet  251  and through the second module pipe  204 . The second module pipe  204  then directs the flow of coolant towards the module coolant outlet port  240  of the second module flange  216  directly coupled with the second engine coolant inlet port  269 . 
     The EGR cooler module  248  using this configuration is also able to receive exhaust gases from the first engine EGR outlet port  247  of the cylinder head  235  via the module EGR inlet port  220  of the first module flange  214 . The exhaust gas flows out of the first engine EGR outlet port  247  of the cylinder head  235  and through module EGR inlet port  220  (directly coupled to the first engine EGR outlet port  247 ) of the first module flange  214  into the EGR cooler module  248 . Additionally, the EGR cooler module  248  is able to return cooled exhaust gas to the first engine EGR inlet port  259  of the cylinder head  235  via the module EGR outlet port  242  of the second module flange  216 . The cooled exhaust gas flows out of the housing EGR outlet  271  and through the third module pipe  206 . The third module pipe  206  then directs the flow of cooled exhaust gas towards the module EGR outlet port  242  of the second module flange  216  directly coupled to the first engine EGR inlet port  259 . 
     In this configuration, the flanges of the EGR cooler module may be bolted to the first cylinder head surface  249  of the cylinder head  235  so that the inlet/outlet ports (e.g., ports  218 ,  220 ,  240 , and  242 ) of the EGR cooler module  248  are in face-sharing contact with the corresponding ports (e.g.,  267 ,  247 ,  269 , and  259 ) of the cylinder head  235 . This eliminates the use of extra fittings and/or passages for routing fluids to/from the EGR cooler module  248  and achieves a compact form for the EGR cooler module  248 . For example, the embodiment of the EGR cooler module shown by  FIG. 2  includes four input/output ports (e.g., two input ports and two output ports) directly coupled to corresponding engine ports on the same side of the cylinder head to facilitate the transfer of coolant and EGR gases to/from the EGR cooler module. All four ports are parallel to the same side of the cylinder head and all four are arranged in a common plane. Additionally, all four ports are in face-sharing contact with (and are shaped to couple with) their corresponding ports on the cylinder head (e.g., the engine coolant outlet port is in face-sharing contact with the module coolant inlet port, the engine EGR outlet port is in face-sharing contact with the module EGR inlet port, etc.). 
       FIG. 3  depicts a schematic including a second embodiment of an engine system  300  as well as including an EGR system  301 . Engine system  300  shown by  FIG. 3  includes an engine  302 , a cylinder head  334 , and an integrated exhaust manifold (IEM)  332 . Many of the components included in engine system  300  are also included in engine system  100  of  FIG. 1  and are labeled similarly in  FIG. 3  and may not be re-introduced. The passages and components shown by  FIG. 3  are not shown to scale and the relative positioning, size, and number of passages may vary between physical embodiments (e.g., such as the embodiment shown by  FIGS. 4-6 ). 
     The embodiment of the engine system  300  of  FIG. 3  includes an EGR cooler module  348  directly coupled to a single side of the cylinder head  334 . The EGR cooler module  348  possesses a module coolant inlet port  365 , a module coolant outlet port  371 , a module EGR inlet port  353 , and a module EGR outlet port  357 . 
     The engine system  300  shown by  FIG. 3  includes three cylinders  120 ,  122 , and  124  with respective intake ports  114 ,  116 , and  118  and exhaust ports  126 ,  128 , and  130 . The engine system  300  also includes the exhaust runners  136 ,  138 , and  140  coupled to cylinders  120 ,  122 , and  124  respectively. The exhaust runners merge at internal exhaust junction  142  which routes through manifold exhaust passage  145  to manifold exhaust port  144 . Manifold exhaust port  144  is fluidically coupled with external exhaust passage  146 , as described by the discussion of  FIG. 1  above. The engine system  300  also includes intake passage  104 , throttle  109 , intake manifold  106 , and cylinder intake passages  108 ,  110 , and  112  for the intake of combustible gases. The internal passage  150  (e.g., the first internal passage  150  shown by  FIG. 1 ) is a peripheral exhaust passage downstream of internal exhaust junction  142  (and is internal to the cylinder head  334 ) and is fluidically coupled to both manifold exhaust passage  145  and the first engine EGR outlet port  151  (as described by the discussion of  FIG. 1  above). 
     The internal passage  150  (e.g., internal to the cylinder head  334  and routing through the cylinder head  334 ) receives a portion of the exhaust gases flowing through manifold exhaust passage  145  (as described in the discussion of  FIG. 1 ). In alternate embodiments, the first internal passage  150  may be positioned upstream of internal exhaust junction  142  and may be a peripheral passage (as described above) to one or more exhaust runners (such as exhaust runners  136 ,  138 , and  140 ) of one or more cylinders (such as cylinders  120 ,  122 , and  124 ). In these alternate embodiments, the first internal passage  150  may receive a portion of exhaust gases from one or more runners of one or more cylinders but it does not receive exhaust gases downstream of a junction at which exhaust from all of the cylinders converges (e.g., internal exhaust junction  142 ). 
     The internal passage  150  routes gases through the cylinder head  334  from the manifold exhaust passage  145  to the first engine EGR outlet port  151 . The first engine EGR outlet port  151  is in fluidic communication with the module EGR inlet port  353  of the EGR cooler module  348  (as described in the discussion of  FIGS. 4-6  below). The module EGR outlet port  357  of the EGR cooler module  348  is in fluidic communication with an external EGR passage  361  (e.g., external to both the cylinder head  334  and the EGR cooler module  348 ) via an EGR inlet port  355  of the external EGR passage  361 . An EGR valve  156  is coupled inline with the external EGR passage  361 . The external EGR passage  361  is also in fluidic communication with the intake EGR inlet port  163  of the intake manifold  106 . The EGR valve  156  may be actuated by an actuator (not shown) to control the flow of gases from the module EGR outlet port  357  of the EGR cooler module  348 , through the external EGR passage  361 , to the intake EGR inlet port  163 , and into the intake manifold  106 . 
     In the embodiment of  FIG. 3 , the intake EGR inlet port  163  is upstream of the cylinder intake passages  108 ,  110 , and  112  within the intake manifold  106 . Alternate embodiments may exist in which the intake EGR inlet port is not upstream of all of the cylinder intake passages and may be downstream of one or more of the cylinder intake passages. Alternate embodiments may additionally include a plurality of external EGR passages (similar to external EGR passage  361 ) coupling the module EGR outlet port  357  to one or more intake EGR inlet ports (similar to intake EGR inlet port  163 ) at the intake manifold and/or one or more cylinder intake passages. 
     The radiator  162  is coupled to the first engine coolant inlet port  166  via the first external coolant passage  164 . The first engine coolant inlet port  166  is fluidically coupled to the plurality of coolant passages  160  internal to the cylinder head  334  and surrounding the components of the cylinder head as described by the discussion of  FIG. 1  above. The plurality of coolant passages  160  are fluidically coupled to the internal passage  158  (e.g., the third internal passage  158  shown by  FIG. 1 ) which is fluidically coupled to the first engine coolant outlet port  167 . 
     Similar to the example of EGR cooler module  148  shown by  FIG. 1 , the EGR cooler module  348  contains a plurality of passages (not shown) to facilitate the transfer of heat from the exhaust gas received through the module EGR inlet port  353  to a supply of coolant within the EGR cooler module  348 . The passages within the EGR cooler module  348  containing exhaust gases and the passages within the EGR cooler module  348  containing coolant are separated and not in fluidic communication with each other. However, the gas passages and coolant passages are proximate to each other and may be simultaneously proximate to a material with high thermal conductivity (e.g., metal). Heat may transfer from the gas within the exhaust gas passages through a proximate thermally conductive material and into the coolant. In this way, the EGR cooler module  348  cools the gas exiting the module such that the gas entering the module is at a higher temperature than the gas exiting the module. 
     The coolant within the EGR cooler module  348  is supplied through the module coolant inlet port  365  of the EGR cooler module  348 . The module coolant inlet port  365  is fluidically and directly coupled to the first engine coolant outlet port  167  and receives coolant from the internal passage  158 . Coolant is routed through the coolant passages  160  from the radiator  162  and into the internal passage  158  (as described above in the discussion of  FIG. 1 ). 
     The plurality of coolant passages (not shown) within the EGR cooler module  348  return coolant to the module coolant outlet port  371  which is fluidically coupled to a coolant inlet port  369  of a second external coolant passage  372  (e.g., external to both the cylinder head  334  and the EGR cooler module  348 ). The coolant transfers from the module coolant outlet port  371  into the second external coolant passage  372  via the coolant inlet port  369 . The second external coolant passage  372  is coupled to (and in fluidic communication with) both the radiator  162  and the coolant inlet port  369 . In this arrangement, coolant may exit the EGR cooler module  348  through the module coolant outlet port  371  and into the directly coupled coolant inlet port  369 . The coolant then flows through the second external coolant passage  372  and enters the radiator  162 . 
     In the configuration of the engine system  300  as described above, the EGR cooler module  348  receives coolant from the first engine coolant outlet port  167  and exhaust gas from the first engine EGR outlet port  151 . The proximate passages internal to the EGR cooler module  348  then transfer thermal energy away from the exhaust gas and into the coolant. The cooled exhaust gas exits the EGR cooler module  348  via module EG outlet port  357  and enters the external EGR passage  361  via EGR inlet port  355  where it is routed to the EGR inlet port  163  of the intake manifold  106 . The flow of the cooled gas through external EGR passage  361  into the intake manifold  106  is controlled by EGR valve  156 . 
     The coolant exits the EGR cooler module  348  through the module coolant outlet port  371  and enters the second external coolant passage  372  via the coolant inlet port  369  (directly coupled to module coolant outlet port  371 ). The coolant flows out of the second external coolant passage  372  and into the radiator  162 . In this way, the EGR cooler module  348  uses coolant from an internal coolant passage  158  of the cylinder head  334  and exhaust gas from an internal gas passage  150  of the cylinder head to cool exhaust gases from the cylinders ( 120 ,  122 , and  124 ). It then routes the cooled gases into the intake manifold  106  via an EGR passage  361  external to the cylinder head  334  and routes the coolant into the radiator  162  via a coolant passage (e.g., second external coolant passage  372 ) external to the cylinder head  334 . 
     By directly coupling to the surface of the cylinder head and directly interfacing with the coolant outlet and the EGR outlet on the cylinder head, the EGR cooler module is able to receive EGR gas and coolant from the cylinder head without additional fittings, and may transmit coolant and EGR gas to passages external to the cylinder head. For example, the embodiment of the EGR cooler module shown by  FIG. 3  includes four module input/output ports (e.g., two input ports and two output ports), with two of the ports directly coupled to corresponding engine ports on a same side of the cylinder head to facilitate the transfer of coolant and EGR gases to the EGR cooler module. Both of the ports directly coupled to the same side of the cylinder head are also parallel to the same side of the cylinder head (e.g., both ports are parallel to a common plane). Additionally, both ports are in face-sharing contact with (and are shaped to couple with) their corresponding ports on the cylinder head (e.g., the engine coolant outlet port is in face-sharing contact with the module coolant inlet port, and the engine EGR outlet port is in face-sharing contact with the module EGR inlet port). 
     The cylinder head  334  of the engine system  300  of  FIG. 3  does not include the second internal passage  152 , the fourth internal passage  168 , the first engine EGR inlet port  155 , the second engine EGR outlet port  154 , the second engine coolant inlet port  169 , or the second engine coolant outlet port  170 . However, alternate embodiments may exist in which one or more or all of these components are included with the cylinder head. 
       FIGS. 4-6  show a second embodiment of an EGR system including an EGR cooler module directly coupled to a side of a cylinder head of an engine system. Specifically,  FIG. 4  shows a perspective view of a first side of a cylinder head in an arrangement similar to the cylinder head configuration described above during the discussion of  FIG. 3 . The cylinder head is included as part of a second embodiment of the EGR system shown by  FIGS. 4-6 . The second embodiment of the EGR system shown by  FIGS. 4-6  is similar in arrangement to the EGR system included in the embodiment of the engine system shown by  FIG. 3 .  FIG. 4  illustrates the first side of the cylinder head without the EGR cooler module attached to show the ports and mounting surfaces of the first side of the cylinder head.  FIG. 5  shows in an alternate perspective view the same EGR system including the same cylinder head shown by  FIG. 4 , with the EGR cooler module directly coupled to two of the ports of the cylinder head. The EGR cooler module is also coupled to an external EGR passage and includes a port that may be coupled with an external coolant passage (not shown).  FIG. 6  shows a third view of the EGR system including the cylinder head and EGR cooler shown by  FIGS. 4-5 , with the cylinder head shown in cross-section. The view shown by  FIG. 6  illustrates the circulation paths of coolant and EGR gases between the EGR cooler module, the cylinder head, and the external passages, with the components of the EGR system in the same arrangement as shown by  FIGS. 4-5 . A shared set of axes are included in each of  FIGS. 4-6  for comparison. 
       FIG. 4  shows a first perspective view of an embodiment of an EGR system  413  of an engine system  415  including a cylinder head  434  (e.g., such as the cylinder head  334  of  FIG. 3 ) in a configuration similar to that shown by the schematic of  FIG. 3 . The cylinder head  434  includes a first cylinder head surface  400  (on a first side of the cylinder head) and a second cylinder head surface  401  (on a different, second side of the cylinder head). The first and second cylinder head surfaces are approximately perpendicular to each other (as shown by axes  411 ). The first cylinder head surface  400  includes two mounting surfaces  409  and  410  (e.g., first mounting surface  409  and second mounting surface  410 ). The mounting surfaces  409  and  410  are planar (e.g., flat) portions of the first cylinder head surface  400  and are parallel to each other. The first mounting surface  409  includes two eyelets (e.g., holes)  405  and  406 , as well as a first engine EGR outlet port  451  (e.g., such as first engine EGR outlet port  151  shown in  FIG. 3 ). The second mounting surface  410  includes two eyelets (e.g., holes)  407  and  408 , as well as a first engine coolant outlet port  467  (e.g., such as first engine coolant outlet port  167  shown by  FIG. 3 ). The eyelets of the first mounting surface  409  and the second mounting surface  410  (e.g., the eyelets  405  and  406 , and the eyelets  407  and  408 , respectively) are sized and shaped to accommodate bolts. 
     In the example of the embodiment of the EGR system  413  shown by  FIG. 4 , each mounting surface ( 409  and  410 ) has two eyelets. Alternate embodiments may exist in which each mounting surface has a different number of eyelets (e.g., three, four, etc.) and each mounting surface may have a different number of eyelets than the other mounting surface (e.g., first mounting surface  409  has a different number of eyelets than second mounting surface  410 ). The eyelets of the mounting surfaces  409  and  410  are formed such that each may accept a threaded end of a bolt. 
       FIG. 4  shows an external EGR passage  461  (e.g., such as external EGR passage  361  shown by  FIG. 3 ). An external passage flange  402  is coupled to an end of the external EGR passage  461 . An EGR inlet port  455  (e.g., such as EGR inlet port  355 ) is included in the external passage flange  402 . The external EGR passage  461  and the external passage flange  402  are coupled (or formed together) such that fluid (e.g., EGR gases) may transfer through the EGR inlet port  455  and into the external EGR passage  461 . 
     The external passage flange  402  also includes a plurality of eyelets (e.g., eyelets  403  and  404 ) sized and shaped to accommodate bolts. The eyelets (e.g., holes) of the external passage flange  402  are formed such that each may accept a threaded end of a bolt. In the example of the embodiment of the EGR system  413  shown by  FIG. 4 , the external passage flange  402  has two eyelets  403  and  404 . Alternate embodiments may exist in which the external passage flange has a different number of eyelets (e.g., three, four, etc.). 
       FIG. 4  additionally includes an optional port  417  of the cylinder head  434 . In the embodiment of the EGR system  413  shown by  FIGS. 4-6 , the optional port  417  is not utilized (e.g., the port is inactive and does not transfer fluid to/from the cylinder head). However, in alternate embodiments of the EGR system, the optional port may function as an engine coolant inlet port to facilitate the transfer of coolant from the EGR cooler module to an internal passage of the cylinder head. In this way, the EGR cooler may receive coolant from the first engine coolant outlet port and return coolant to the engine coolant inlet port (e.g., the optional port). 
       FIG. 5  shows a perspective view of the second embodiment of the EGR system shown by  FIG. 4 , and includes an EGR cooler module  548  mounted to the cylinder head  434 . As described above, the embodiment of the EGR system  413  included in  FIGS. 4-6 , including EGR cooler module  548  directly coupled to cylinder head  434  (shown by  FIG. 5 ), is similar in arrangement to the EGR system  301  shown by  FIG. 3 . The EGR cooler module  548  is mounted to the first cylinder head surface  400  of the cylinder head  434  in the configuration described during the discussion of  FIGS. 3-4  above. The EGR cooler module  548  includes a housing  500 , a plurality of rigid pipes (e.g., pipes  502 ,  504 , and  506 ) and a plurality of flanges (e.g., flanges  514 ,  515 , and  516 ). The housing, rigid pipes, and flanges of the EGR cooler module  548  may be constructed of a material (e.g., metal) resistant to wear by corrosion and/or high temperatures associated with engine fluids and gases. The housing, rigid pipes, flanges, and other components of the EGR cooler module may be formed together (e.g., molded) as one piece and/or may be fused together (e.g., welded). As introduced above, the housing (e.g., body)  500  of the EGR cooler module  548  includes a plurality of cooling tubes and exhaust passages disposed therein to facilitate the exchange of heat from exhaust gas to coolant. 
     In the example of the embodiment of the EGR cooler module  548  shown in  FIG. 5 , the housing  500  of the EGR cooler module  548  is formed such that the shape of the EGR cooler module  548  is approximately a rectangular parallelepiped. The housing  500  possesses an outward module surface  552  (e.g., outward facing surface relative to the cylinder head) that is parallel to the first cylinder head surface  400  of the cylinder head  434  when the EGR cooler module  548  is mounted to the cylinder head  434  (as described below). The outward module surface  552  is joined to a plurality of perpendicular module surfaces (e.g., surfaces  553 ,  554 ,  555 , and  556 ) which are arranged perpendicular to the outward module surface  552 . The perpendicular module surfaces are joined to an inward module surface  557  (e.g., facing the first cylinder head surface  400 ) which is arranged parallel to (and opposite from) the outward module surface  552 . In the example of the embodiment of the EGR cooler module  548  shown by  FIG. 5 , the perpendicular module surfaces  553 ,  554 , and  555  are planar (e.g., flat) while the perpendicular module surface  556  possesses a plurality of curves forming a curved end of the housing  500 . The inward module surface  557  and outward module surface  552  are both planar (e.g., flat) and both the outward module surface  552  and the inward module surface  557  may be joined to the perpendicular surfaces with or without rounded edges. Alternate embodiments may exist in which the EGR cooler module possesses additional curves or fewer curves and/or has additional surfaces or fewer surfaces. 
     The housing  500  of the EGR cooler module  548  of  FIG. 5  is directly coupled (e.g., formed as one piece or fused together) with the three rigid pipes  502 ,  504 , and  506  (which may hereafter be referred to as the first module pipe  502 , the second module pipe  504 , and the third module pipe  506 ) of the EGR cooler module  548 . A first end (e.g., an end originating from the housing) of the first module pipe  502  is coupled to a housing coolant inlet  565  of the housing  500 . A first end (e.g., an end originating from the housing) of the second module pipe  504  is coupled to a housing coolant outlet  571  of the housing  500  and a first end (e.g., an end originating from the housing) of the third module pipe  506  is coupled to a housing EGR inlet  561  of the housing  500 . 
     The rigid pipes  502 ,  504 , and  506 , and the housing coolant inlet  565 , housing coolant outlet  571 , and housing EGR inlet  561  in the example of the embodiment shown in  FIG. 5  are arranged such that the housing inlets ( 565 ,  571 , and  561 ) and first ends (as described above) of the pipes ( 502 ,  504 , and  506 ) are positioned along the plurality of perpendicular module surfaces. The housing coolant inlet  565  (and the first end of the first module pipe  502 ) is positioned along the perpendicular module surface  553  (which may hereafter be referred to as first module perpendicular surface  553 ). The housing coolant outlet  571  (as well as the first end of the second module pipe  504 ) is positioned along the perpendicular surface  555  (which may hereafter be referred to as second module perpendicular surface  555 ). The housing EGR inlet  561  (as well as the first end of the third module pipe  506 ) is positioned along the perpendicular surface  554 . 
     The flange  514  (which may be referred to as first module flange  514 ) is arranged parallel to the inward and outward module surfaces ( 557  and  552  respectively) and is joined with (e.g., formed from and/or welded to) the inward module surface  557 . The first module flange  514  projects outward from the housing  500  of the EGR cooler module  548  away from the perpendicular module surface  556 . The flange  515  (which may be referred to as second module flange  515 ) is arranged parallel to the inward and outward module surfaces ( 557  and  552  respectively) and is joined with (e.g., formed from and/or welded to) a second end (e.g., the end not originating from the housing  500 ) of the first module pipe  502 . The second module flange  515  and the first module pipe  502  project outward from the housing  500  of the EGR cooler module  548  away from the perpendicular module surface  553 . The flange  516  (which may be referred to as third module flange  516 ) is arranged parallel to the inward and outward module surfaces ( 557  and  552  respectively) and is joined with (e.g., formed from and/or welded to) a second end (e.g., the end not originating from the housing  500 ) of the third module pipe  506 . The third module flange  516  and the third module pipe  506  project outward from the housing  500  of the EGR cooler module  548  away from the perpendicular module surface  554 . Because the first module flange  514 , the second module flange  515 , and the third module flange  516  are simultaneously parallel to the inward and outward module surfaces ( 557  and  552  respectively), the first module flange  514 , the second module flange  515 , and the third module flange  516  are also parallel to each other. The first module flange  514 , second module flange  515 , and the third module flange  516 , are all parallel to the first cylinder head surface  400  (and first side of the cylinder head). 
     The first module flange  514  includes a module EGR outlet port  518  fluidically coupled to (and in face-sharing contact with) the EGR inlet port  455  of the external EGR passage  461 . In this arrangement, the module EGR outlet port  518  facilitates the flow of coolant from the EGR cooler module and into the EGR inlet port  455  of the external EGR passage  461 . 
     The first module flange  514  also includes a plurality of eyelets (e.g., eyelets  524  and  526 ) sized and shaped to accommodate bolts. In the example of the embodiment of the first module flange  514  shown by  FIG. 5 , the first module flange  514  has two eyelets  524  and  526 . Alternate embodiments may exist in which the first module flange has a different number of eyelets (e.g., three, four, etc.). The eyelets (e.g., holes) are configured on the first module flange  514  in an arrangement that matches the arrangement of the plurality of eyelets (e.g., eyelets  403  and  404  shown by  FIG. 4 ) of the external passage flange  402 . The eyelets  524  and  526  of the first module flange  514  in the embodiment shown in  FIG. 5  are configured to align with the eyelets  403  and  404  when the first module flange  514  is directly coupled and in face-sharing contact with the external passage flange  402 . The eyelets  403  and  404  are formed such that they may accept the threaded ends of the bolts passing through the eyelets  524  and  526 . 
     The module EGR outlet port  518  of the first module flange  514  is configured such that when the first module flange  514  is directly coupled (e.g., bolted) to the external passage flange  402  of the external EGR passage  461 , the module EGR outlet port  518  is in face-sharing contact with the EGR inlet port  455  of the external EGR passage  461 . A gasket (not shown) may be secured between the first module flange  514  and the external passage flange  402  such that the gasket permits fluidic communication without leakage between the module EGR outlet port  518  and the EGR inlet port  455 . The gasket may be formed from a material suitable for contact with corrosive and/or high-temperature gases from the cylinder head  434  (e.g., a rubber-like material). 
     The second module flange  515  includes a module coolant inlet port  540  fluidically and directly coupled to (and in face-sharing contact with) the first engine coolant outlet port  467  (as shown by  FIG. 4 ) of the cylinder head  434 . The module coolant inlet port  540  is also fluidically coupled to (and in face-sharing contact with) a second end (e.g., an end not originating from the housing  500 ) of the first module pipe  502 . In this arrangement, the module coolant inlet port  540  facilitates the flow of coolant from the first engine coolant outlet port  467 , through the first module pipe  502 , and into the housing coolant inlet  565  of the housing  500 . 
     The second module flange  515  also includes a plurality of eyelets (e.g., eyelets  544  and  546 ) sized and shaped to accommodate bolts. In the example of the embodiment of the second module flange  515  shown by  FIG. 5 , the second module flange  515  has two eyelets  544  and  546 . Alternate embodiments may exist in which the second module flange has a different number of eyelets (e.g., three, four, etc.). The eyelets (e.g., holes) are configured on the second module flange  515  in an arrangement that matches the arrangement of the plurality of eyelets (e.g., eyelets  407  and  408 ) of the second mounting surface  410  of the cylinder head  434  (as shown by  FIG. 4 ). The eyelets  544  and  546  of the second module flange  515  in the embodiment shown in  FIG. 5  are configured to align with the eyelets  407  and  408  when the second module flange  515  is placed flush against the second mounting surface  410 . The eyelets  407  and  408  are formed such that they may accept the threaded ends of the bolts passing through the eyelets  544  and  546 . 
     The module coolant inlet port  540  of the second module flange  515  is configured such that when the second module flange  515  is bolted to the second mounting surface  410  of the cylinder head  434 , the module coolant inlet port  540  is directly coupled to and in face-sharing contact with the first engine coolant outlet port  467  of the cylinder head  434 . A gasket (not shown) may be secured between the second module flange  515  and the second mounting surface  410  such that the gasket permits fluidic communication without leakage between the module coolant inlet port  540  and the first engine coolant outlet port  467 . The gasket may be formed from a material suitable for contact with corrosive and/or high-temperature fluids from the cylinder head  434  (e.g., a rubber-like material). 
     The third module flange  516  includes a module EGR inlet port  525  directly and fluidically coupled to (and in face-sharing contact with) the first engine EGR outlet port  451  (as shown by  FIG. 4 ) of the cylinder head  434 . The module EGR inlet port  525  is also fluidically coupled to (and in face-sharing contact with) a second end (e.g., an end not originating from the housing  500 ) of the third module pipe  506 . In this arrangement, the module EGR inlet port  525  facilitates the flow of coolant from the first engine EGR outlet port  451 , through the third module pipe  506 , and into the housing EGR inlet  561  of the housing  500 . 
     The third module flange  516  also includes a plurality of eyelets (e.g., eyelets  521  and  523 ) sized and shaped to accommodate bolts. In the example of the embodiment of the third module flange  516  shown by  FIG. 5 , the third module flange  516  has two eyelets  521  and  523 . Alternate embodiments may exist in which the third module flange has a different number of eyelets (e.g., three, four, etc.). The eyelets (e.g., holes) are configured on the third module flange  516  in an arrangement that matches the arrangement of the plurality of eyelets (e.g., eyelets  405  and  406 ) of the first mounting surface  409  of the cylinder head  434  (as shown by  FIG. 4 ). The eyelets  521  and  523  of the third module flange  516  in the embodiment shown in  FIG. 5  are configured to align with the eyelets  405  and  406  when the third module flange  516  is coupled in face-sharing contact with the first mounting surface  409 . The eyelets  405  and  406  are formed such that they may accept the threaded ends of the bolts passing through the eyelets  521  and  523 . 
     The module EGR inlet port  525  of the third module flange  516  is configured such that when the third module flange  516  is directly coupled (e.g., bolted) to the first mounting surface  409  of the cylinder head  434 , the module EGR inlet port  525  is in face-sharing contact with the first engine EGR outlet port  451  of the cylinder head  434 . A gasket (not shown) may be secured between the third module flange  516  and the first mounting surface  409  such that the gasket permits fluidic communication without leakage between the module EGR inlet port  525  and the first engine EGR outlet port  451 . The gasket may be formed from a material suitable for contact with corrosive and/or high-temperature fluids from the cylinder head  434  (e.g., a rubber-like material). 
     As described in the discussion of  FIG. 3 , the first engine EGR outlet port  451  is directly coupled to (e.g., formed by) an internal passage (e.g., such as internal passage  150  shown by  FIG. 3 ) of the cylinder head  434 , and the first engine coolant outlet port  467  is directly coupled to (e.g., formed by) an internal passage (e.g., such as internal passage  158  shown by  FIG. 3 ) of the cylinder head  434 . 
     By configuring the EGR cooler module  548  and cylinder head  434  in this way, the EGR cooler module  548  is able to receive coolant from the first engine coolant outlet port  467  of the cylinder head  434  via the module coolant inlet port  540  on the second module flange  515 . The coolant flows out of the first engine coolant outlet port  467  of the cylinder head  434  and through the module coolant inlet port  540  into the first module pipe  502 . The first module pipe  502  then directs the flow of coolant towards the housing coolant inlet  565  of the housing  500 . Additionally, the EGR cooler module  548  is able to return coolant to a radiator (e.g., such as radiator  162  shown by  FIG. 3 ) via an external coolant passage (e.g., such as second external coolant passage  372  shown by  FIG. 3 ). The coolant flows out of the module coolant outlet port  571  and through the second module pipe  504 . The second module pipe  504  then directs the flow of coolant to a module coolant outlet port  573  arranged within a second end (e.g., an end not originating from the housing  500 ) of the second module pipe  504 . The module coolant outlet port  573  is in face-sharing contact and fluidically coupled with an inlet of an external coolant passage (e.g., such as second external coolant passage  372  shown by  FIG. 3 ). The external coolant passage then directs coolant towards the radiator (e.g., such as radiator  162  shown by  FIG. 3 ). 
     The EGR cooler module  548  using this configuration is also able to receive exhaust gases from the first engine EGR outlet port  451  of the cylinder head  434  via the module EGR inlet port  525  on the third module flange  516 . The exhaust gas flows out of the first engine EGR outlet port  451  of the cylinder head  434  and through module EGR inlet port  525  (directly coupled to the first engine EGR outlet port  451 ) of the third module flange  516  into the EGR cooler module  548 . Additionally, the EGR cooler module  548  is able to route cooled exhaust gas to the external EGR passage  461  via the module EGR outlet port  518  on the first module flange  514 . The module EGR outlet port  518  is fluidically (and directly) coupled to the EGR inlet port  455  of the external passage flange  402  and directs the flow of cooled exhaust gas into the external EGR passage  461 . 
     In this configuration, the second and third flanges ( 515  and  516 ) of the EGR cooler module  548  may be directly coupled (e.g., bolted) to the first cylinder head surface  400  of the cylinder head  434  so that the ports (e.g., module coolant inlet port  540  and module EGR inlet port  525 ) of the second and third flanges (respectively) of the EGR cooler module  548  are in face-sharing contact (and fluidically coupled) with the corresponding ports (e.g., first engine coolant outlet port  467  and first engine EGR outlet port  451 ) of the cylinder head to facilitate the transfer of coolant and EGR gas into the EGR cooler module  548 . This eliminates the use of extra fittings and/or passages for routing fluids into the EGR cooler module  548  and achieves a compact form for the EGR cooler module  548 . 
       FIG. 6  shows an additional perspective view of the embodiment of the EGR system  413  included in the engine system  415  shown by  FIGS. 4-5 .  FIG. 6  shows the cylinder head  434  in cross-section with the EGR cooler module  548  directly coupled to the first cylinder head surface  400  of the cylinder head  434 . The perspective shown by  FIG. 6  is approximately perpendicular to that shown by  FIGS. 4-5  (as indicated by axes  411 ). The flow of gas and coolant through the cylinder head  434  is shown by a plurality of arrows indicating the direction of flow. 
     The cylinder head  434  of the engine system  415  interfaces with a plurality of cylinders, such as cylinder  601 . While a four-cylinder configuration is shown in the embodiment of engine system  415 , other embodiments may include a different number of cylinders (e.g., three, six, eight, etc.). Each cylinder is shown coupled to a plurality of exhaust ports that direct flow to a plurality of exhaust runners. While the cylinders in the embodiment of the engine system  415  and EGR system  413  shown by  FIG. 6  are coupled to two exhaust ports and two exhaust runners each, other embodiments may show each cylinder coupled to a different number of exhaust ports and/or exhaust runners (e.g., one, three, etc.). 
     The cylinder  601  is shown coupled to exhaust ports  603  and  605 . The cylinder  601  may exhaust gases through exhaust ports  603  and  605  via an exhaust valve disposed within each exhaust port (as described in the discussion of  FIG. 3 ). Exhaust port  603  is fluidically coupled to exhaust runner  609  and exhaust port  605  is fluidically coupled to exhaust runner  607  as part of an integrated exhaust manifold (IEM)  617 . The flow of exhaust from cylinder  601  through exhaust runner  609  is indicated approximately by arrow  600 . The flow of exhaust from cylinder  601  through exhaust runner  607  is indicated approximately by arrow  602 . The flows as indicated by arrows  600  and  602  mix and converge at an internal exhaust junction  619  within the IEM  617 . 
     A peripheral exhaust passage  621  (e.g., similar to first internal passage  150  shown by  FIG. 3 ) is fluidically coupled to the internal exhaust junction  619  and the first engine EGR outlet port  451 . A portion of the exhaust gases from cylinder  601  (e.g., the portion of gases not flowing in the direction of arrow  604 ) flow through the peripheral exhaust passage  621  along a path approximately indicated by the arrow  606 . The gases flow through the first engine EGR outlet port  451  and into the EGR cooler module  548  via module EGR inlet port  525 , as described by the discussion of  FIG. 5  above. The exhaust gases route through the EGR cooler module  548  and experience a reduction in thermal energy due to the proximity of the gases with the coolant passages included within (e.g., internal to) the EGR cooler module  548 , as described by the discussion of  FIG. 3  above. The cooled exhaust gas then exits the EGR cooler module  548  via the module EGR outlet port  518  and enters the external EGR passage  461  via a direct coupling between the module EGR outlet port  518  and the EGR inlet port  455 , as described by the discussion of  FIG. 5  above and as indicated by the flow direction arrow  608 . 
     The embodiment of the EGR system  413  shown by  FIG. 6  includes the peripheral exhaust passage  621  fluidically coupled to the exhaust flow downstream of the cylinder  601  and not downstream of additional engine cylinders. Said another way, as shown in  FIG. 6 , the peripheral exhaust passage  621  is fluidly coupled to only one cylinder (cylinder  601 ) of the engine. However, other embodiments may include the peripheral exhaust passage  621  being coupled downstream of one or more or each of the engine cylinders. The peripheral exhaust passage  621  may also be arranged downstream of a different cylinder, or downstream of a different cylinder and one or more or each of the cylinders additional to the fluidically coupled cylinder. 
     Coolant exits the cylinder head  434  and enters the EGR cooler module  548  via module coolant inlet port  540  from a passage  623  (e.g., such as third internal passage  158  shown by  FIG. 3 ) internal to the cylinder head  434  (e.g., a passage passing through an interior of the cylinder head). The coolant exits the cylinder head via first engine coolant outlet port  467  and enters the EGR cooler module  548  via the module coolant inlet port  540 , as described by the discussion of  FIG. 5  and indicated by the flow direction arrow  610 . The coolant receives thermal energy from the exhaust gas within the EGR cooler module  548  via a plurality of proximate passages as described by the discussion of  FIG. 3 . The coolant then exits the EGR cooler module  548  and enters an external coolant passage (not shown) via the module coolant outlet port  573  as described by the discussion of  FIG. 5  and as indicated by the flow direction arrow  612 . 
       FIG. 2  and  FIGS. 4-6  show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above/below one another, at opposite sides to one another, or to the left/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example. 
       FIG. 7  depicts a flowchart  700  describing a method for routing exhaust gases from cylinders of a cylinder head and through an EGR system including an EGR cooler module, such as EGR system  201  and EGR cooler module  248  shown in  FIG. 2  or EGR system  413  and EGR cooler module  548  shown by  FIGS. 5-6 . 
     At  702 , the method includes routing exhaust gas internally through a cylinder head from an exhaust passage downstream of an engine cylinder to an EGR inlet port (e.g., module EGR inlet port  220  shown in  FIG. 2  or module EGR inlet port  525  shown in  FIGS. 5-6 ) of an EGR cooler directly coupled to a first side of the cylinder head. For example, exhaust gas may be routed through an exhaust passage internal to the cylinder head (e.g., first internal passage  150  shown by  FIG. 1  and  FIG. 3 ) and into an EGR cooler module (e.g., EGR cooler module  248  shown by  FIG. 2  or EGR cooler module  548  shown by  FIGS. 5-6 ) via the respective inlet ports described above. 
     At  704 , the method includes flowing exhaust gas through the EGR cooler from the EGR inlet port to an EGR outlet port (e.g., module EGR outlet port  242  shown in  FIG. 2  or module EGR outlet port  518  shown in  FIGS. 5-6 ) of the EGR cooler (e.g., EGR cooler module  248  shown by  FIG. 2  or EGR cooler module  548  shown by  FIGS. 5-6 ) and then to an intake manifold. In a first embodiment, flowing exhaust to the intake manifold at  704  includes internally routing exhaust gas through the cylinder head from the EGR outlet port to a cylinder head outlet port (e.g., second engine EGR outlet port  154  shown in  FIG. 1 ) coupled to the intake manifold. For example, in the first embodiment, the EGR cooler module (e.g., EGR cooler module  248  shown by  FIG. 2 ) receives exhaust gas flow at a module EGR inlet port (e.g, module EGR inlet port  220  shown by  FIG. 2 ) and outputs cooled exhaust gas to a module EGR outlet port (e.g., module EGR outlet port  242  shown by  FIG. 2 ). The gas then flows through a passage (e.g., second internal passage  152  shown by  FIG. 1 ) internal to a cylinder head (e.g., cylinder head  235  shown by  FIG. 2 ) to an intake manifold (e.g., intake manifold  106  shown by  FIG. 1 ). In a second embodiment, flowing gas to the intake manifold includes flowing exhaust gas from the EGR outlet port of the EGR cooler and externally to the intake manifold via an external EGR passage arranged outside of the cylinder head. For example, in the second embodiment, the EGR cooler module (e.g., EGR cooler module  548  shown by  FIG. 5 ) receives exhaust gas flow at a module EGR inlet port (e.g, module EGR inlet port  525  shown by  FIG. 5 ) and outputs cooled exhaust gas to a module EGR outlet port (e.g., module EGR outlet port  518  shown by  FIG. 5 ). The cooled gas then flows from the module EGR outlet port into an external EGR passage (e.g., external EGR passage  461  shown by  FIGS. 4-6 ) via an EGR inlet port (e.g., EGR inlet port  455 ) of the external EGR passage. 
     At  706 , the method includes flowing coolant from inside the cylinder head to a coolant inlet port (e.g., module coolant inlet port  218  show by  FIG. 2 , or module coolant inlet port  540  shown by  FIGS. 5-6 ) of the EGR cooler (e.g., EGR cooler module  248  shown by  FIG. 2  or EGR cooler module  548  shown by  FIGS. 5-6 ) and then through the EGR cooler. For example, coolant may be routed through a coolant passage internal to the cylinder head (e.g., third internal passage  158  shown by  FIG. 1  and  FIG. 3 ) and into the EGR cooler module via an engine coolant outlet port (e.g., first engine coolant outlet port  167  shown by  FIG. 1  and  FIG. 3 ) directly coupled to a module coolant inlet port (e.g., module coolant inlet port  218  shown by  FIG. 2 , or module coolant inlet port  540  shown by  FIGS. 5-6 ) of the EGR cooler module. 
     At  708 , the method includes flowing coolant from a coolant outlet port (e.g., module coolant outlet port  240  shown by  FIG. 2 , or module coolant outlet port  573  shown by  FIGS. 5-6 ) of the EGR cooler to a radiator, where the EGR inlet port, EGR outlet port, and coolant inlet port of the EGR cooler face a same side of the cylinder head. In a first embodiment, the method at  708  includes flowing coolant from the coolant outlet port to the radiator by internally routing coolant through the cylinder head from the coolant outlet port to a cylinder head outlet port coupled to the radiator. For example, coolant may flow from the coolant outlet port (e.g., module coolant outlet port  240  shown by  FIG. 2 ) of the EGR cooler module (e.g., EGR cooler module  248  shown by  FIG. 2 ), to an internal coolant passage (e.g., fourth internal passage  168  shown by  FIG. 1 ) internal to the cylinder head, through a coolant outlet port (e.g., second engine coolant outlet port  170  shown by  FIG. 1 ), and into the radiator (e.g., radiator  162  shown by  FIG. 1 ). In a second embodiment, the method at  708  includes flowing coolant from the coolant outlet port to the radiator via an external coolant passage arranged outside of the cylinder head. For example, coolant may flow from the coolant outlet port (e.g., module coolant outlet port  573  shown by  FIGS. 5-6 ) of the EGR cooler module (e.g., EGR cooler module  548  shown by FIGS.  5 - 6 ), to the external coolant passage (e.g., second external coolant passage  372  shown by  FIG. 3 ) external to the cylinder head, and into the radiator (e.g., radiator  162  shown by  FIG. 3 ). 
     In this way, an EGR cooler module included in an EGR system may be directly mounted to a single side of a cylinder head of an engine. The EGR cooler module may be directly coupled (e.g., mounted) to a plurality of inlet/outlet ports included in the single side of the cylinder head in order to form interfaces between the inlet/outlet ports of the EGR cooler module and the corresponding inlet/outlet ports of the cylinder head. The technical effect of directly mounting the EGR cooler module to a single side of the cylinder head and forming interfaces between the corresponding inlet/outlet ports is to permit the transfer of coolant and EGR gases from the cylinder head to the EGR cooler module inlet ports, and to permit the transfer of coolant and EGR gases from the EGR module outlet ports to the radiator and the intake manifold respectively. In this way, additional external fittings for coupling the EGR cooler to the passages of the cylinder head are not needed, thereby increasing ease of installation and reducing degradation of the fittings over time. Further, the arrangement described above may reduce overall packaging space of the engine. The transfer of coolant/EGR gas from the cylinder head to the EGR cooler module inlet ports is accomplished by directly coupling the module inlet ports to corresponding cylinder head outlet ports fluidically coupled with coolant/EGR gas passages internal to the cylinder head. The transfer of coolant/EGR gas from EGR cooler module to the radiator and intake manifold is accomplished by coupling the EGR cooler module outlet ports to additional coolant/EGR passages internal to the cylinder head (as in a first embodiment) or coupling the EGR cooler module outlet ports to coolant/EGR passages external to the cylinder head (as in a second embodiment). 
     In one embodiment, an exhaust gas recirculation (EGR) system includes an EGR cooler module including a body and an EGR inlet port, EGR outlet port, and coolant inlet port, all extending from the body and arranged in parallel with one another and at a same, first side of a cylinder head, where the EGR inlet port and coolant inlet port are directly coupled to the first side of the cylinder head. In a first example of the exhaust gas recirculation (EGR) system, the EGR outlet port is directly coupled to an engine EGR inlet port, the EGR inlet port is directly coupled to an engine EGR outlet port arranged in the first side of the cylinder head, and the coolant inlet port is directly coupled to an engine coolant outlet port arranged in the first side of the cylinder head. A second example of the exhaust gas recirculation (EGR) system optionally includes the first example and further includes wherein the engine EGR outlet port is directly coupled to an internal EGR passage routed through an inside of the cylinder head from the engine EGR outlet port to an exhaust passage downstream of a cylinder and within the cylinder head. A third example of the exhaust gas recirculation (EGR) system optionally includes one or more or both of the first and second examples, and further includes wherein the exhaust passage is an exhaust runner of only one cylinder of a plurality of engine cylinders and wherein only exhaust gas from the one cylinder is routed through the EGR cooler module. A fourth example of the exhaust gas recirculation (EGR) system optionally includes one or more or each of the first through third examples, and further includes wherein the engine coolant outlet port is directly coupled to a first internal coolant passage routed through an inside of the cylinder head from a second internal coolant passage circulating coolant around cylinders of the engine and the engine coolant inlet port. A fifth example of the exhaust gas recirculation (EGR) system optionally includes one or more or each of the first through fourth examples, and further includes wherein the engine EGR inlet port includes a flange coupled to an external EGR pipe coupled between the EGR outlet port and an intake manifold of the engine. A sixth example of the exhaust gas recirculation (EGR) system optionally includes one or more or each of the first through fifth examples, and further includes wherein the external EGR pipe includes an EGR valve disposed therein. A seventh example of the exhaust gas recirculation (EGR) system optionally includes one or more or each of the first through sixth examples, and further includes wherein the engine EGR inlet port is arranged in the first side of the cylinder head. An eighth example of the exhaust gas recirculation (EGR) system optionally includes one or more or each of the first through seventh examples, and further includes wherein the engine EGR inlet port is directly coupled to an internal EGR passage routed through an inside of the cylinder head from the engine EGR inlet port to a cylinder head exit port arranged at a second side of the cylinder block and coupled to an external EGR passage coupled between the cylinder head exit port and an intake manifold of the engine. A ninth example of the exhaust gas recirculation (EGR) system optionally includes one or more or each of the first through eighth examples, and further includes wherein the EGR cooler module further includes a coolant outlet port directly coupled to an engine coolant inlet port arranged in the first side of the cylinder block, the engine coolant inlet port directly coupled to an internal coolant passage routed through an inside of the cylinder block. A tenth example of the exhaust gas recirculation (EGR) system optionally includes one or more or each of the first through ninth examples, and further includes wherein the EGR cooler module further includes a coolant outlet port directly coupled to an external coolant passage routing coolant from the EGR cooler module to a radiator. 
     A method for an exhaust gas recirculation (EGR) system includes routing exhaust gas internally through a cylinder head from an exhaust passage downstream of an engine cylinder to an EGR inlet port of an EGR cooler directly coupled to a first side of the cylinder head; flowing exhaust gas through the EGR cooler from the EGR inlet port to an EGR outlet port of the EGR cooler and then to an intake manifold; flowing coolant from inside the cylinder head to a coolant inlet port of the EGR cooler and then through the EGR cooler; and flowing coolant from a coolant outlet port of the EGR cooler to a radiator, where the EGR inlet port, EGR outlet port, and coolant inlet port of the EGR cooler face a same side of the cylinder head. In a first example of the method, the method includes flowing exhaust gas to the intake manifold includes flowing exhaust gas from the EGR outlet port of the EGR cooler to the intake manifold via an external EGR passage arranged outside of the cylinder head. A second example of the method optionally includes the first example and further includes adjusting a flow of exhaust gas from the exhaust passage to the intake manifold via adjusting a position of an EGR valve arranged in the external EGR passage. A third example of the method optionally includes one or more or both of the first and second examples, and further includes wherein flowing exhaust to the intake manifold includes internally routing exhaust gas through the cylinder head from the EGR outlet port to a cylinder head outlet port coupled to the intake manifold. A fourth example of the method optionally includes one or more or each of the first through third examples, and further includes adjusting a flow of exhaust gas from the exhaust passage to the intake manifold via adjusting a position of an EGR valve arranged in a passage coupled between the cylinder head outlet port and the intake manifold. A fifth example of the method optionally includes one or more or each of the first through fourth examples, and further includes wherein flowing coolant from the coolant outlet port to the radiator includes flowing coolant from the coolant outlet port to the radiator via an external coolant passage arranged outside of the cylinder head. A sixth example of the method optionally includes one or more or each of the first through fifth examples, and further includes wherein flowing coolant from the coolant outlet port to the radiator includes internally routing coolant through the cylinder head from the coolant outlet port to a cylinder head outlet port coupled to the radiator. 
     In another embodiment, an exhaust gas recirculation (EGR) system includes an EGR cooler module including a housing including a body and four engine connection ports including a module EGR inlet port, module EGR outlet port, module coolant inlet port, and module coolant outlet port, the four connection ports extending from the body and all arranged in a common plane; and a cylinder head including a single side having four module connection ports including an engine EGR outlet port shaped to couple with the module EGR inlet port, an engine EGR inlet port shaped to couple with the module EGR outlet port, an engine coolant outlet port shaped to couple with the module coolant inlet port, and an engine coolant inlet port shaped to couple with the module coolant outlet port. In a first example of the exhaust gas recirculation (EGR) system, the cylinder head includes a first internal passage within an interior of the cylinder head and coupled between an exhaust passage downstream of an engine cylinder and the engine EGR outlet port, where exhaust gases are routed internally through the cylinder head via the first internal passage and to the EGR cooler module. 
     Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. 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. 
     It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein. 
     The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.