Abstract:
The present disclosure provides for a vehicle engine having an EGR system where pairs of cylinders are directly connected to each other. For example, a first and second cylinder may be operably connected by a valve actuator where a high energy, blowdown exhaust gas from the first cylinder may flow through a first flow path directly from the first cylinder to the second cylinder. Likewise, during the firing stroke of the second cylinder, a high-energy, blowdown exhaust gas may flow from the second cylinder through a second flow path directly into the first cylinder. This arrangement may pair cylinders to take advantage of high-energy exhaust gas.

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates to an internal combustion engine. In particular, the present invention relates to an exhaust gas recirculation (“EGR”) system and method to operate the system using paired cylinders. 
     2. Background 
     In various engines, exhaust gases may be generated as combustion chambers or cylinders perform their firing strokes. Exhaust gas recirculation (“EGR”) is a widely used method to utilize these exhaust gases to improve combustion efficiency. In general, EGR improves fuel consumption and reduces emission of nitrogen oxides (“NOx”) by recirculating exhaust gases through engine cylinders as they intake fuel and air. 
     Modern EGR systems may utilize high pressure routing, in which exhaust gas is redirected into a combustion chamber or cylinder from other cylinders, or low pressure routing, in which exhaust gas is redirected into cylinders after going through a catalytic converter. In both of these systems, exhaust gases are ultimately exhausted from the engine through an exhaust pathway. These gases may be redirected along many points in their exhaust pathways back to the cylinders to perform EGR. There still exists a need for improved EGR systems and methods to operate these systems. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention may include any of the following embodiments in various combinations and may also include any other aspect described below in the written description or in the attached drawings. In a first embodiment, this disclosure provides an internal combustion engine having a first, second, third, and fourth cylinder. Each cylinder may have four ports: a primary intake port, a primary exhaust port, an auxiliary intake port, and an auxiliary exhaust port. 
     For example, the first cylinder may have a first auxiliary exhaust port operably connected to a first auxiliary exhaust valve. The first cylinder may also have a first auxiliary intake port operably connected to a first auxiliary intake valve. Likewise, the second cylinder may have a second auxiliary exhaust port operably connected to a second auxiliary exhaust valve, and a second auxiliary intake port operably connected to a second auxiliary intake valve. A flow path may directly connect the first and second cylinders. 
     The engine may further have a valve actuator operably connected to the first auxiliary exhaust and intake valves and the second auxiliary exhaust and intake valves to open and close the first auxiliary exhaust and intake ports and the second auxiliary exhaust and intake ports, respectively. The valve actuator may operate the valves to directly connect the first auxiliary exhaust port to only the second auxiliary intake port (by way of the flow path), and directly connect the second auxiliary exhaust port to only the first auxiliary intake port (by way of the flow path). This may provide direct exchange of exhaust gases between the first and second cylinders. 
     In a further embodiment, the engine may include the third cylinder having a third auxiliary exhaust port operably connected to a third auxiliary exhaust valve, and a third auxiliary intake port operably connected to a third auxiliary intake valve. Likewise, the fourth cylinder may have a fourth auxiliary exhaust port operably connected to a fourth auxiliary exhaust valve, and a fourth auxiliary intake port operably connected to a fourth auxiliary intake valve. 
     The valve actuator may operably connected to the third auxiliary exhaust and intake valves and the fourth auxiliary exhaust and intake valves to open and close the third auxiliary exhaust and intake ports and the fourth auxiliary exhaust and intake ports, respectively. The valve actuator may operate the valves to directly connect the third auxiliary exhaust port to only the fourth auxiliary intake port, and directly connect the fourth auxiliary exhaust port to only the third auxiliary intake port. 
     This arrangement may provide direct exchange of exhaust gases between the third and fourth cylinders. Further, this embodiment may be arranged such that neither the first cylinder nor the second cylinder is fluidically connected to either of the third cylinder or the fourth cylinder via their respective auxiliary exhaust and intake ports. 
     The engine may have an exhaust gas exchange manifold having a first chamber and a second chamber. The first chamber may directly connect the first cylinder to only the second cylinder, and the second chamber may directly connect the third cylinder to only the fourth cylinder. Each chamber may have a length and a volume. For example, the first chamber has a first length and a first volume, and the second chamber has a second length and a second volume. The first length may be about the same as the second length; the first volume may be about the same as the second volume. “About” or “substantially” mean that two given quantities (e.g. lengths or volumes) are within 10% of each other, preferably within 5% of each other, more preferably within 1% of each other. For example, the quantity of the first length is within 10% of the quantity of the second length. This allows accounting for manufacturing tolerances to provide substantially equal chambers. In some embodiments, the first chamber is not in fluid communication or out of fluid communication with the second chamber. 
     The engine also may have rocker arms to control the auxiliary valves. For example, a first rocker arm may be operably connected to the first auxiliary intake valve, in a first intake position, the first rocker arm being operably connected to the first auxiliary exhaust valve, in a first exhaust position. The engine may have a second rocker arm being operably connected to the second auxiliary intake valve, in a second intake position, the second rocker arm being operably connected to the second auxiliary exhaust valve, in a second exhaust position. 
     The first rocker may be moveable between the first auxiliary exhaust and intake positions by the valve actuator having a first rocker arm lobe, the first rocker arm lobe having 360° rotation about the valve actuator. The first rocker arm may be in the first exhaust position when the first rocker arm lobe is positioned at about 50° rotation about the valve actuator. In addition, the first rocker arm may be in the first exhaust position when the second rocker arm is in the second intake position, and the first rocker arm may be in the first intake position when the second rocker arm is in the second exhaust position. This may provide exchange of exhaust gases between the first and second cylinders. 
     The engine may have a third rocker arm being operably connected to the third auxiliary intake valve, in a third intake position, the third rocker arm being operably connected to the third auxiliary exhaust valve, in a third exhaust position. The engine may have a fourth rocker arm being operably connected to the fourth auxiliary intake valve, in a fourth intake position, the fourth rocker arm being operably connected to the fourth auxiliary exhaust valve, in a fourth exhaust position. 
     Because of the arrangements discussed herein, the engine may generate a first exhaust gas that flows from the first auxiliary exhaust port only to the second auxiliary intake port. The engine may generate a second exhaust gas that flows from the second auxiliary exhaust port only to the first auxiliary intake port. Further, the exhaust gas exchange manifold includes a cooling element disposed about the first and second chambers to cool the exhaust gases. 
     In a second embodiment, the engine may define a longitudinal axis and have a primary exhaust manifold, an exhaust gas recirculation manifold, a first cylinder, and a second cylinder. In this embodiment, the first cylinder may be positioned between a first side and a second side of the engine. The first side may be opposite the second side about the longitudinal axis. The first cylinder may have a first primary exhaust port operably connected to a first primary exhaust valve, a first primary intake port operably connected to a first primary intake valve, a first auxiliary exhaust port operably connected to a first auxiliary exhaust valve, and a first auxiliary intake port operably connected to a first auxiliary intake valve. 
     The second cylinder may be positioned in-line with the first cylinder, the second cylinder also being between the first side and the second side. The second cylinder may have a second primary exhaust port operably connected to a second primary exhaust valve, a second primary intake port operably connected to a second primary intake valve, a second auxiliary exhaust port operably connected to a second auxiliary exhaust valve, and a second auxiliary intake port operably connected to a second auxiliary intake valve. The primary exhaust manifold may be positioned on the first side of the engine, and the exhaust recirculation manifold may be positioned on the second side of the engine. 
     The first primary exhaust and intake ports and the second primary exhaust and intake ports may be positioned on the first side. The first auxiliary exhaust and intake ports and the second auxiliary exhaust and intake ports may be positioned on the second side. The first and second primary exhaust port may be in selective fluid communication with the primary exhaust manifold, and the first and second auxiliary exhaust and intake ports may be in selective fluid communication with the exhaust gas recirculation manifold. 
     In this embodiment, the gas recirculation manifold may have a first flow path connected to the first auxiliary exhaust port and extending only from the first auxiliary exhaust port to the second auxiliary intake port. The first flow path may be in selective fluid communication with the first cylinder and the second cylinder by way of the first auxiliary exhaust port and the second auxiliary intake port. The exhaust gas recirculation manifold may also have a second flow path connected to the second auxiliary exhaust port and extending only from the second auxiliary exhaust port to the first auxiliary intake port. The second flow path may be in selective fluid communication with the first cylinder and the second cylinder by way of the second auxiliary exhaust port and the first auxiliary intake port. 
     In yet another embodiment, this disclosure provides a method of operating exhaust gas recirculation in an internal combustion engine. The method comprises providing an engine having a first cylinder and a second cylinder. The first cylinder may have a first primary exhaust port, a first primary intake port, a first auxiliary exhaust port, and a first auxiliary intake port. Likewise, the second cylinder may have a second primary exhaust port, a second primary intake port, a second auxiliary exhaust port, and a second auxiliary intake port. 
     The method may include (1) intaking air into the second cylinder via the second primary intake port; (2) firing the first cylinder, wherein firing the first cylinder generates a first exhaust gas; (3) exhausting a portion of the first exhaust gas through only the first auxiliary exhaust port; (4) intaking the portion of the first exhaust gas from the first auxiliary exhaust port into only the second auxiliary intake port; and (5) exhausting a remainder of the first exhaust gas through the first primary exhaust port. 
     The method may also include (1) intaking air into the first cylinder via the first primary intake port; (2) firing the second cylinder, wherein firing the second cylinder generates a second exhaust gas; (3) exhausting a portion of the second exhaust gas through only the second auxiliary exhaust port; (4) intaking the portion of the second exhaust gas from the second auxiliary exhaust port into only the first auxiliary intake port; and (5) exhausting a remainder of the second exhaust gas through the second primary exhaust port. 
     If the engine has a third cylinder and a fourth cylinder, the method may include providing the third cylinder having a third primary exhaust port, a third primary intake port, a third auxiliary exhaust port, and a third auxiliary intake port. In this embodiment, the fourth cylinder may have a fourth primary exhaust port, a fourth primary intake port, a fourth auxiliary exhaust port, and a fourth auxiliary intake port. 
     The method may further include (1) intaking air into the fourth cylinder via the fourth primary intake port; (2) firing the third cylinder, wherein firing the third cylinder generates a third exhaust gas; (3) exhausting a portion of the third exhaust gas through only the third auxiliary exhaust port; (4) intaking the portion of the third exhaust gas from the third auxiliary exhaust port into only the fourth auxiliary intake port; and (5) exhausting a remainder of the third exhaust gas through the third primary exhaust port. 
     The method may further include (1) intaking air into the third cylinder via the third primary intake port; (2) firing the fourth cylinder, wherein firing the fourth cylinder generates a fourth exhaust gas; (3) exhausting a portion of the fourth exhaust gas through only the fourth auxiliary exhaust port; (4) intaking the portion of the fourth exhaust gas from the fourth auxiliary exhaust port into only the third auxiliary intake port; and (5) exhausting a remainder of the fourth exhaust gas through the fourth primary exhaust port. 
     As one possible advantage of the above described embodiments and arrangements, the EGR system described herein may provide a direct pairing between cylinders and direct routing of exhaust gases from one cylinder to another. This direct routing may allow the intaking cylinder receiving the blowdown exhaust gas during its intaking stroke to take advantage of the initial high pressure, high energy exhaust gas. As will be apparent to one skilled in the art, if such high energy gas had to be routed through various pathways, possibly being longer in length, this gas would not retain as much high energy upon entering the intaking cylinder. 
     The present disclosure may be better understood by referencing the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a partial, schematic top view of an internal combustion engine in accordance with embodiments of the present invention; 
         FIGS. 2A-G  depict operation steps of the engine of  FIG. 1 ; 
         FIGS. 3A-C  depict cylinder firing sequences of the engine of  FIG. 1 ; 
         FIGS. 4A-C  depict a valve actuation system of the engine of  FIG. 1 ; and 
         FIGS. 5A-B  depict chambers of the engine of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure will now be described more fully with reference to the accompanying figures, which show preferred embodiments. The accompanying figures are provided for general understanding of the structure of various embodiments. However, this disclosure may be embodied in many different forms. These figures should not be construed as limiting and they are not necessarily to scale. 
     The following definitions will be used in this application. 
     “BDC” refers to bottom dead center. 
     “EG” refers to exhaust gas. 
     “SOHO” refers to single overhead cam. 
     “TDC” refers to top dead center. 
     “TWC” refers to a three way catalyst or three-way catalytic converter. 
       FIG. 1  depicts a schematic top view of an internal combustion engine in accordance with embodiments of the present invention.  FIG. 1  depicts four cylinders ( 16 ,  76 ,  106 ,  46 ) in-line with each other. As will become apparent, one skilled in the art will understand that any number of even cylinders may be used in this engine, and the cylinders may be in-line or rotated (e.g. in V-shape or the like). The four cylinders of the engine, being in-line, define a longitudinal axis  138 . The longitudinal axis  138  generally splits the engine shown into two opposing sides of the engine ( 1 ,  2 ). 
     The first side  11  contains the primary intake manifold  15  and the primary exhaust manifold  17 . The second side  13  contains the EGR manifold  6 , constructed in accordance with the teachings of the present disclosure. As depicted in  FIG. 1 , intake air may come into the engine via the primary intake manifold  15 , coupled to a throttle and cooled by a water cooled air cooler (“WCAC”). Similarly, EG may leave through the primary exhaust manifold  17 , a turbine, and TWC. 
     Each of the four cylinders depicted preferably have four ports operably connected to four valves. For example, the first cylinder  16  has a first primary exhaust port  21  operably connected to a first primary exhaust valve  19 , and a first primary intake port  25  connected to a first primary intake valve  23 . The first cylinder  16  also has a first auxiliary exhaust port  28  operably connected to a first auxiliary exhaust valve  18 , and a first in auxiliary intake port  36  connected to a first auxiliary intake valve  30 . In further example, the second cylinder  46  may also have a second auxiliary exhaust port  58  operably connected to a second auxiliary exhaust valve  48 , and a second auxiliary intake port  66  operably connected to a second auxiliary intake valve  60 . 
     The engine may further have a valve actuator, such as a camshaft, (not shown here) connected to the first auxiliary exhaust and intake valves and the second auxiliary exhaust and intake valves to open and close the first auxiliary exhaust and intake ports and the second auxiliary exhaust and intake ports, respectively. The valve actuator may operate the valves to directly connect the first auxiliary exhaust port  28  to only the second auxiliary intake port  66 . Likewise, the valve actuator may also directly connect the second auxiliary exhaust port  58  two only the first auxiliary intake ports  36 . This provides direct exchange of EG between only the first and second cylinders ( 16 ,  46 ). 
     As shown in  FIG. 1 , the engine may further have a third cylinder  76  and a fourth cylinder  106 . Just as with the first and second cylinders, the third cylinder  76  may have a third auxiliary exhaust ports  88  operably connected to a third auxiliary exhaust valve  78 , and a third auxiliary intake port  96  operably connected to a third auxiliary intake valve  90 . The fourth cylinder  106  may have a fourth auxiliary exhaust port  118  operably connected to the fourth auxiliary exhaust valve  108 , and a fourth auxiliary intake port  126  operably connected to a fourth auxiliary intake valve  120 . 
     As described above, the valve actuator may operably connect to the third auxiliary exhaust and intake valves and the fourth auxiliary exhaust and intake valves to open and close the third auxiliary exhaust and intake ports and the fourth auxiliary exhaust and intake ports, respectively. The valve actuator may operate the valves to directly connect the third auxiliary exhaust port  88  to only the fourth auxiliary intake port  126 , and directly connecting the fourth auxiliary exhaust ports  118  to only the third auxiliary intake port  96 . This provides direct exchange of EG only between the third and fourth cylinders ( 76 ,  106 ). 
     By directly providing EGR between the first and second cylinders (or third and fourth cylinders) EG phasing is simplified. Likewise, issues with controlled distribution among the cylinders (mal-distribution) are mitigated or eliminated. The structure to preform EGR is also simplified, as a single manifold with limited piping and a single cam shaft can be used in this design. 
     This direct exchange of EG may be accomplished by the formation of the EGR manifold  6 . The EGR manifold  6  may comprise a first flow path  38  connected to the first auxiliary exhaust port  28  and extending only from the first auxiliary exhaust port  28  to the second auxiliary intake port  66 . The first flow path  38  may be in selective fluid communication with the first cylinder  16  and the second cylinder  46  by way of the first auxiliary exhaust port  28  and a second auxiliary intake port  66 . 
     Similarly, the EGR manifold  6  may comprise a second flow path  68  connected to the second auxiliary exhaust port  58  and extending only from the second auxiliary exhaust port  58  to the first auxiliary intake port  36 . The second flow path  68  may be in selective fluid communication with the first cylinder  16  and a second cylinder  46  by way of the second auxiliary exhaust or  58  and the first auxiliary intake port  36 . In this way, a first exhaust gas  44  may flow from the first auxiliary exhaust port  28  only to the second auxiliary intake port  66 . A second exhaust gas  74  may flow from the second auxiliary exhaust port  58  only to the first auxiliary intake port  36 . The engine may generate a third exhaust gas  104  in a third flow path  98  and a fourth exhaust gas  134  in a fourth flow path  128 , each being similar to the first and second EGs ( 44 ,  74 ). 
     The first flow path  38  and a second flow path  68  may be formed similarly. For example, the first flow path  38  and a second flow path  68  may have the same length and accommodate the same volume. In one example, the first flow path may have a first flow path length  40  and the second flow path may have a second flow path length  70  such that each length is less than or equal to 1 meter (m). This 1 meter or shorter length may provide advantages in the direct flow of blowdown EG. 
     It will be apparent that neither of the first cylinder  16  nor the second cylinder  46  may be fluidly connected to either of the third cylinder  76  or the fourth cylinder  106  via their respective auxiliary exhaust and intake ports. 
       FIG. 1  also depicts two chambers within the EGR manifold  6 . For example, the EGR manifold  6  may have a first chamber  8  with a first length and a first volume  10 , and a second chamber  12  with a second length and a second volume  14 . Both chambers ( 10 ,  12 ) may be visible here, but it may be apparent that one chamber may also be obscured by the other (e.g. under the other) in a top view. 
     The first chamber  8  may directly connect the first cylinder  16  to only the second cylinder  46 . The second chamber  12  may directly connect the third cylinder  76  to only the fourth cylinder  106 . As with the first and second flow path lengths ( 40 ,  70 ), the first length may be about or substantially the same as the second length. Likewise, the first volume  10  may be about the same or substantially the same as the second volume  14 . The first chamber  8  may not be in fluid communication, or out of fluid communication with, the second chamber  12 . 
     In  FIG. 1 , each manifold depicted may have a cooling element disposed about the manifold. For example, cooling element or unit  160  may be disposed about the primary intake manifold  15 , and cooling element  162  may be disposed about the EGR manifold  6 . The cooling element may be water cooled, air cooled, and the like, as will be known to a person of ordinary skill in this art. 
     Each cylinder may have primary ports located on the first side  11  and secondary ports located on the second side  2 . For example, the first cylinder  16  is positioned between the first side  11  and a second side  13  of the engine. The first cylinder  16  has a first primary exhaust port  21  and a first primary intake port  25  positioned on the first side  1 , and the first auxiliary exhaust port  28  and the second auxiliary exhaust port  36  being positioned on the second side  2 . 
     Likewise, the second cylinder  46  has the second primary exhaust and intake ports being positioned on the first side  1 , and the second auxiliary exhaust port  58  and the second auxiliary intake port  66  being positioned on the second engine side  2 . In this arrangement, the first and second primary exhaust ports are in selective fluid communication with the primary exhaust manifold  17 . Thus, first and second auxiliary exhaust and intake ports are in selective fluid communication with the EGR manifold  6 . This arrangement is also seen with the third and fourth cylinders ( 76 ,  106 ). 
     By providing EGR exhausting and intaking on the same side of the engine, the flow paths can be shortened (e.g. &lt;1 m). In addition, this arrangement may allow for simplified routing (e.g. a single manifold without additional pipes). 
       FIG. 2  depicts side views of the engine described herein performing EGR. As described above, the engine may have four cylinders with four ports each. In  FIG. 2 , only two ports are shown per cylinder because the two other ports may be obscured. The first cylinder  16  has a first primary exhaust port  21  and a first primary intake port  25 . The first cylinder  16  also has a first auxiliary exhaust port and a first auxiliary intake port (obscured by the primary ports). 
     The ports may be operably connected to a valve actuator, such as camshaft  136 . The auxiliary valves (obscured in this view) may be operated by rocker arms ( 20 ,  50 ,  80 ,  110 ), discussed further below. Each rocker arm may be operated by a rocker arm lobe around the camshaft  136  ( 26 ,  56 ,  86 ,  116 ). For example, a first rocker arm  20  may be operated to open and close the first auxiliary intake port by a first rocker arm lobe  26 . This operation will be discussed in further detail in  FIG. 3  below. 
     It will be understood that the second cylinder  46 , the third cylinder  76 , and the fourth cylinder  106  each have the same arrangement as the first cylinder  16 , with a primary exhaust port, a primary intake port, an auxiliary exhaust port, and an auxiliary intake port. In  FIG. 2A , the valve actuator  136  is positioned at 0° crank angle. The first cylinder  16  is at TDC preparing for its firing stroke, and the third cylinder  76  is at BDC after exhausting. In this position, the second cylinder  46  is intaking air via the second primary intake port. 
     In  FIG. 2B , the crank angle has rotated to 50° and the first cylinder  16  is in its firing stroke, generating a first exhaust gas. Firing pushes the first cylinder  16  towards BDC, and exhausts a portion of the first exhaust gas through only the first auxiliary exhaust port. After the first exhaust gas is exhausting through only the first auxiliary exhaust port, the second cylinder  46  is intaking the portion of the first exhaust gas from the first auxiliary exhaust port into only the second auxiliary intake port. After the portion of the first exhaust gas has is intaken into the second cylinder  46 , a remainder of the first exhaust gas is exhausted through the first primary exhaust port  21 . 
     In  FIG. 2C , the crank angle has rotated to 180°, and the fourth cylinder  106  is preparing for its firing stroke. At this point, the third cylinder  76  is intaking air via the third primary intake port. In  FIG. 2D , the crank angle has rotated to 230°, and the fourth cylinder  106  is in its firing stroke, generating a fourth exhaust gas. A portion of the fourth exhaust gas is exhausted through only the fourth auxiliary exhaust port. The portion of the fourth auxiliary exhaust gas is intaken into only the third auxiliary intake port. Subsequently, a remainder of the fourth exhaust gas is exhausted through the fourth primary exhaust port to empty the cylinder. 
     In  FIG. 2E , the crank angle has rotated to 360°, and the second cylinder  46  is preparing for its firing stroke. In this position, the first cylinder  16  is intaking air via the first primary intake port  25 . In  FIG. 2F , the second cylinder  46  is in its firing stroke, generating a second exhaust gas. A portion of the second exhaust gas is exhausted through only the second auxiliary exhaust port. Subsequently, the portion of the second auxiliary exhaust gas is intaken from the second auxiliary exhaust port two only the first auxiliary intake port. After intaking, a remainder of the second exhaust gas is exhausted through the second primary exhaust port. 
     In  FIG. 2G , the crank angle has rotated it to 540° about the valve actuator  136 , and the fourth cylinder is intaking air via the fourth primary intake port. Subsequently, the third cylinder may fire, wherein firing the third cylinder generate a third exhaust gas. A portion of the third exhaust gas may exhaust through only the third auxiliary exhaust port. Then, the portion of the third exhaust gas may be intaken from the third auxiliary exhaust port into only the fourth auxiliary intake port. Subsequently, a remainder of the third exhaust gas may be exhausted through the third primary exhaust port. 
     As shown in  FIGS. 2A-G , the overall firing sequence and blowdown sequence may be: cylinder  16 , cylinder  106 , cylinder  46 , cylinder  76 . The overall intaking sequence may be: cylinder  46 , cylinder  76 , cylinder  16 , cylinder  106 . 
       FIGS. 3A-C  show further details of firing and intaking for two paired cylinders. For example, the first cylinder  16  with piston  210  is in its firing stroke. In this firing stroke, at 50° crank angle, the intake port  36  would be closed and the exhaust port  28  would be exhausting from the first cylinder  16  into the second cylinder  46 . The second cylinder  46  with piston  220  may be in its intaking stroke. In this position, the second cylinder  46  would be intaking EG directly from the first auxiliary exhaust port  28  into the second auxiliary intake for  66 . The second auxiliary exhaust port  58  would be closed. 
     When cylinder  16  is intaking, first primary intake valve  23  will be open for air  170  and the first auxiliary intake valve  30  will be open to intake second exhaust gas  74 . Line B-B depicts a top view, shown further in  FIG. 3B .  FIG. 3B  shows the top of the first and second cylinders ( 16 ,  46 ) when the first cylinder  16  is in its firing stroke and the second cylinder  46  is in it intaking stroke. First auxiliary exhaust port  28  is open to allow first flow path  38  to connect from only the first auxiliary exhaust port  28  directly into the second auxiliary intake port  66 , which is also open. 
     Simultaneously, the second primary intake port of the second cylinder  46  is also open. At this time, the second primary exhaust port of the second cylinder  46  is closed, the second auxiliary exhaust port  58  is closed, and the second flow path  68  contains no EG. The first auxiliary intake port  36  is closed, and the first primary exhaust and intake ports ( 21 ,  25 ) are also closed. 
       FIG. 3C  shows graphs of the paired first and second cylinders ( 16 ,  46 ). For example, the first cylinder  16  begins exhausting a first exhaust gas at approximately 50° crank angle, showing in peak  222 . After a portion of the first exhaust gas is exhausted, the remainder of the first exhaust gas exhausts through the first primary exhaust port, in peak  224 . Around 360° crank angle, the first cylinder  16  began intaking air, shown in peak  226 . 
     Correspondingly, the second cylinder  46  is finishing exhausting a second exhaust gas through the second primary exhaust port, in peak  228 . Subsequently in peak  230 , the second cylinder  46  begins it intaking stroke. This intaking stroke begins slightly before the first cylinder  16  starts to exhaust the first exhaust gas (peak  222 ). Next in peak  232 , the second cylinder  46  begins intaking the first exhaust gas through the second auxiliary intake port. 
       FIGS. 4A-C  show further details of the valve actuator and rocker arms for controlling the cylinders. The valve actuator  136  may be a SOHO. More preferably, the valve actuator  136  has a cam-in-cam arrangement to accommodate operation of the primary and auxiliary valves.  FIG. 4A  depicts each cylinder having three operably connected lobes around the cam  136 . Lobe E may control the primary exhaust valve. Lobe I may control the primary intake valve. The third lobe positioned with each cylinder may control the rocker arm associated with each cylinder (i.e. a rocker arm lobes  26 ,  56 ,  86 ,  116 ). 
     Line B-B depicts a top view shown in  FIG. 4B .  FIG. 4B  depicts a top view. The cam  136  is positioned above the primary exhaust and intake valves of each cylinder. In addition, the auxiliary exhaust and intake valves are shown next to the primary exhaust and intake valves. Each auxiliary exhaust and intake valve has a corresponding rocker arm positioned above.  FIG. 4C  depicts one exemplary rocker arm (e.g. first rocker arm  20 ). 
     The first rocker arm  20  will be used as an example to demonstrate the details of any rocker arm ( 50 ,  80 ,  110 ). The first rocker arm  20  may be operably connected to the first auxiliary intake valve, in a first intake position. The first intake position allows the first cylinder to intake directly from the second cylinder. The first rocker arm  20  may be operably connected to the first auxiliary exhaust valve, in a first exhaust position. The first exhaust position allows the first cylinder to exhaust directly into the second cylinder. 
     Likewise, the second rocker arm  50  may be operably connected to the second auxiliary intake valve, and a second intake position. The second rocker arm  50  may also be operably connected to the second auxiliary exhaust valve, and a second exhaust position. The first rocker arm  20  may be movable between the first exhaust and intake position by the valve actuator  136  because the valve actuator may have a first rocker arm lobe  26 . The first rocker arm lobe  26  may have 360° rotation about the valve actuator  136 . 
     It may be apparent to one skilled in the art that the first rocker arm  20  may be in the first exhaust position when the second rocker arm  50  may be in the second intake position. Correspondingly, the first rocker arm  20  may be in the first intake position when the second rocker arm  50  is in the second exhaust position. This arrangement may provide for exchange of EG between the first and second cylinders. 
     As stated above, a third rocker arm  80  may be operably connected to the third auxiliary intake valve, in a third intake position. The third rocker arm  80  may also be operably connected to the third auxiliary exhaust valve, and a third exhaust position. The fourth rocker arm  110  may be operably connected to the fourth auxiliary intake valve, and a fourth intake position. The fourth rocker arm  110  may also be connected operably to the fourth auxiliary exhaust valve, in a fourth exhaust position. 
     It will be understood that the rocker arms could be operated in the opposite manner, such that contacting one rocker arm with an intake valve closes the intake valve and operates the corresponding exhaust position, and contacting the one rocker arm with the exhaust valve closes the exhaust valve and operates the corresponding intake position. Likewise, electronically controlled valves may also be used in place of the camshaft and/or rocker arms. 
       FIG. 5  depicts another view of the chambers ( 8 ,  12 ). In  FIG. 5A , one skilled in the art will understand that second chamber  12  may be obscured by first chamber  8 . The first chamber  8  may have a first volume  10  being equal to the second volume  14  of the second chamber  12 . Additionally, cooling element  160  may be disposed about both chambers. The first flow path  38  may flow from the first cylinder  16  through first chamber  8  into the second cylinder  46 , without flowing into the second chamber at all. Likewise, the second flow path  68  may flow from the second cylinder  46  through the first chamber  8  into the first cylinder  16 . 
     In a similar manner, the third flow path  98  may flow from the third cylinder  76  through the second chamber  12  into the fourth cylinder  106 , without flowing into the first chamber at all. The fourth flow path  128  may flow from the fourth cylinder  106  through the second chamber  12  to the third cylinder  76 . Line B-B depicts an end view of the chambers. In  FIG. 5B , the first chamber  8  is not fluidly connected to the second chamber  12 . 
     It should be understood that the foregoing relates to exemplary embodiments of the disclosure and that modifications may be made without departing from the spirit and scope of the disclosure as set forth in the following claims. While the disclosure has been described with respect to certain embodiments it will be appreciated that modifications and changes may be made by those skilled in the art without departing from the spirit of the disclosure.