Abstract:
A partially integrated manifold assembly is disclosed which improves performance, reduces cost and provides efficient packaging of engine components. The partially integrated manifold assembly includes a first leg extending from a first port and terminating at a mounting flange for an exhaust gas control valve. Multiple additional legs (depending on the total number of cylinders) are integrally formed with the cylinder head assembly and extend from the ports of the associated cylinder and terminate at an exit port flange. These additional legs are longer than the first leg such that the exit port flange is spaced apart from the mounting flange. This configuration provides increased packaging space adjacent the first leg for any valving that may be required to control the direction and destination of exhaust flow in recirculation to an EGR valve or downstream to a catalytic converter.

Description:
STATEMENT OF GOVERNMENT RIGHTS 
     The present invention was made with government support under Cooperative Agreement No. DE-EE0005654 awarded by the Department of Energy. The Government has certain rights in the invention. 
    
    
     FIELD 
     The present disclosure relates to exhaust manifolding for a multiple-cylinder four-cycle internal combustion engine, and more particularly to a partially integrated exhaust manifold coupling an exhaust gas flow control valve with the exhaust port for one cylinder and integrating two or more exhaust runners with the exhaust ports of the remaining cylinders. The control valve selective directs the flow of exhaust gas to an exhaust gas recirculation valve or to a catalytic converter therefor bypassing the inlet system. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     A typical automotive engine is a four-cycle internal combustion device which includes an engine block having multiple cylinders. Each cylinder supports a piston for reciprocating movement. A cylinder head is coupled to a top surface of the engine block such that the block and head define a combustion chamber. The cylinder head includes a set of intake ports and a set of exhaust ports for each cylinder which, in combination with the intake valves and exhaust valves, allow combustion gases to enter and exit the combustion chambers. An intake manifold and an exhaust manifold are typically coupled to the cylinder head for routing the combustion gases to and from the intake and exhaust ports. 
     It is common for a portion of the exhaust gases exiting the combustion chamber to be recirculated through an exhaust gas recirculation or EGR valve to the intake manifold or intake ports. An automotive engine may also be configured with a turbocharger having a turbine or scroll which is driven by the exhaust gases and/or may have a catalytic converter for exhaust gas treatment. As such, these components must also be in fluid communication with the exhaust ports. 
     It is important to locate these components as close as possible to the exhaust manifold. However, other engine components (e.g., valve train, fuel injection, air filters, alternator) and vehicle systems (e.g., transmission, power steering, front suspension, air condition compressor, etc.) must also be located adjacent the engine under the hood of the vehicle. Accordingly, the packaging space for these components can be extremely limited. 
     In a four-cylinder engine designed for running in dedicated exhaust gas recirculation mode, one cylinder is capable of supplying exhaust gas recirculation to all four cylinders. Thus, it may be desirable to separate the exhaust manifolding of this cylinder from the remaining three cylinders. Typically this design requires a single complex stainless steel manifold or two separate stainless steel manifolds. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     A partially integrated exhaust manifold can improve performance, reduce cost and efficiently package the engine components discussed above. The partially integrated exhaust manifold is adapted to be coupled directly to an engine block and includes a first leg extending from a first exhaust port and terminating at a mounting flange for a flow control valve, and at least a second leg extending from the other exhaust ports terminating at an exit port flange. The second leg is longer than the first leg such that the exit port flange is spaced apart from the mounting flange. This configuration allows for increased packaging space adjacent the first leg for any valving that may be required to control the direction/destination of the exhaust flow in recirculation to the intake side of the engine or downstream to the exhaust system including a catalytic converter. 
     In a four-cylinder engine configuration, the second leg may include two runners such that one runner extends from the exhaust ports for cylinder #2 and another runner extends from the exhaust port for cylinder #3. A third leg extends from the exhaust port for cylinder #4. The second and third legs may share a common exit port flange. This embodiment allows for the packaging of a single or dual turbocharger in which the turbo scrolls are driven by the exhaust gases from cylinders #2-4. In the case of a single turbocharger both legs feed the single scroll, and in the case of a dual turbocharger each leg feeds each own scroll. This embodiment also reduces “crosstalk” that may occur in a typical four-cylinder engine, thereby more evenly distributing the residual exhaust gas component for all of the cylinders. 
     The partially integrated exhaust manifold described and illustrated herein may be readily adapted for use in a three-cylinder configuration, wherein the first leg is paired with cylinder #1 and the second leg is paired with cylinders #2 &amp; #3. The partially integrated exhaust manifold described and illustrated herein may also be readily adapted for use with an in-line six-cylinder configuration, wherein the first leg is paired with cylinder #1, the second leg is paired with cylinders #2 &amp; #3, the third leg is paired with cylinders #4 &amp; #5, and a fourth leg is paired with cylinder #6 and manifolded into the first leg. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a schematic top view of a four-cylinder internal combustion engine having a partially integrated exhaust manifold. 
         FIG. 2  is a schematic side view of the partially integrated exhaust manifold shown in  FIG. 1 . 
         FIG. 3  is a schematic perspective view of the partially integrated exhaust manifold shown in  FIG. 1 . 
         FIG. 4  is a schematic top view similar to  FIG. 1  showing the partially integrated exhaust manifold in a three-cylinder configuration. 
         FIG. 5  is a schematic top view similar to  FIG. 1  showing the partially integrated exhaust manifold in an in-line six-cylinder configuration. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known 
     When an element such as a component, member or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element, it may be directly on, engaged, connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element, there may be no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Terms such as first, second, third, etc. may be used herein only to distinguish one element from another. These terms or other similar numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. Likewise, spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe the relationship of one element relative to another as illustrated in the figures. These spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     Referring now to  FIGS. 1-3 , wherein like numerals indicate like parts throughout the several views, a portion of a multiple-cylinder internal combustion engine  10  is schematically represented. Engine  10  includes an engine block  12  having a plurality of cylinders  14  formed therein, a cylinder head assembly  16  coupled to the top of the engine block  12  over the cylinders  14 . A body portion  18  of the cylinder head assembly  16  is coupled to the engine block  12  and has a set of intake ports  20  and a set of exhaust ports  22  in fluid communication with the cylinders. The embodiment illustrated in  FIGS. 1-3  includes four cylinders  14 . 1 ,  14 . 2 ,  14 . 3 ,  14 . 4  (collectively  14 ) having two intake ports  20 . 1 ,  20 . 2  (collectively  20 ) and two exhaust ports  22 . 1 ,  22 . 2  (collectively  22 ) associated with each cylinder  14 . 
     An intake manifold  24  is coupled to the cylinder head assembly  16  for supplying combustion gases (in the form of air or an air/fuel mixture) to the intake ports  20  and through the cylinders  14 . A set of intake valves (not shown) are supported on the cylinder head assembly  16  and operate to selectively open and close the intake ports  20 . A throttle valve  26  is operably coupled to the intake manifold  24  and controls the amount of combustion gases entering the intake manifold  24 . 
     The cylinder head assembly  16  includes a partially integrated exhaust manifold  28  for collecting combustion by-product gases and delivering these exhaust gases to an exhaust system E having a catalytic converter C. As used herein, the term integrated exhaust manifold refers to an integral or monolithic structure forming the body portion  18  of the cylinder head assembly  16  covering the exhaust ports  22  and at least some of the legs  30 . 1 ,  30 . 2 .  30 . 3  (collectively  30 ) of the exhaust manifold  28 . The exhaust manifold  28  is partially integrated in that each leg  30  of the exhaust manifold  28  is separate or independent of the other legs and is further configured to have a separate outlet or exit port  32 . 1 ,  32 . 2 ,  32 . 3  (collectively  32 ) for each leg  30  as compared to terminating at a single outlet for all legs. The cylinder head assembly  16  and partially integrated exhaust manifold  28  described herein can be fabricated using any suitable manufacturing processes known to one of ordinary skill in the art of engine component fabrication. 
     The length of the first leg  30 . 1  is substantially shorter than the length of the second leg  30 . 2  and the length of the third leg  30 . 3 . As presently preferred, the first leg  30 . 1  is about one-quarter to one-third the length of a leg in a conventional exhaust manifold, and more preferably approaches a length typical of the exhaust passageway formed in a conventional cylinder head. The length of the second leg  30 . 2  and the length of the third leg  30 . 3  are substantially equal to the length of the exhaust runners formed in a convention exhaust manifold design. Thus, the length of the second leg  30 . 2  and the length of the third leg  30 . 3  are at least three times the length of the first leg  30 . 1 . Isolating the first leg  30 . 1  from the third leg  30 . 3  has the additional benefit of substantially simplifying the design of the exhaust manifold  28  by eliminating the cross-over configuration required to join the exhaust passageways for cylinder  20 . 1  and  20 . 4  in a convention bifurcated exhaust manifold. 
     The length of the first leg  30 . 1  may also be effectively “shortened” by substantially decreasing the delivery volume of the first leg  30 . 1  relative to the enclosed volume of the second leg  30 . 2  and the third leg  30 . 3 . The delivery volume is defined as the enclosed volume within a given leg between the exhaust port and the exit port circumscribed by the exhaust passageway formed therein. As presently preferred, the delivery volume of the first leg  30 . 1  is substantially smaller that the delivery volume of the second leg  30 . 2  and the delivery volume of the third leg  30 . 3 . More preferably the delivery volume of the second leg  30 . 2  and the delivery volume of the third leg  30 . 3  are at least three times the delivery volume of the first leg  30 . 2 . 
     The first leg  30 . 1  terminates at an end  34  opposite the body portion  18 . Flange  36  is formed on end  34  and has an exit port  32 . 1  formed therethrough. In one embodiment, an exhaust gas control valve  38  is coupled to the flange  36 . The shorter length of the first leg  30 . 1  allows for increased packaging room for any valving that is required to control the direction and destination of the exhaust flow from cylinder  14 . 1  through intake ports  20 . As noted above, the shorter length of the first leg  30 . 1  significantly reduces the volume of exhaust gas between the exhaust ports  22  of cylinder  14 . 1  and the control valve  38  (i.e., the EGR delivery volume), thereby substantially improving the response time for exhaust gas recirculation. 
     An inlet  40  of the control valve  38  is in fluid communication with the first leg  30 . 1 . One outlet  42  of the control valve  38  is in fluid communication with intake ports  22  via an EGR valve  39  and enables dedicated exhaust gas recirculation from the exhaust side of one cylinder  14 . 1  to the intake side of all cylinders  14 . Another outlet  44  of the control valve  38  joins is coupled to the exhaust system E upstream of a catalytic converter C. In operation, the control valve  38  selectively establishes fluid communication for the exit port  32 . 1  and the EGR valve  39  or the catalytic converter C therefor bypassing the inlet system. In practice, the control valve  38  may be used during an engine startup sequence for controlling exhaust gas recirculation and for decreasing catalytic converter warm-up time. 
     The second and third legs  30 . 2 ,  30 . 3  terminate at ends  46 ,  50  opposite the body portion  18 . Flange portions  48 ,  52  are formed at ends  46 ,  50  of second leg  30 . 2  and third leg  30 . 2  respectively. Exit ports  32 . 2 ,  32 . 3  are formed through flange portions  48 ,  52 . In the embodiment illustrated in  FIGS. 1-3 , flange portions  48 ,  52  form a common mounting surface. A turbocharger  54  may be coupled to the flange portions  48 ,  52  such that exhaust gases from cylinders  14 . 2 ,  14 . 3  and  14 . 4  drive the turbocharger  54 . In one embodiment, the turbocharger may be a single turbo such that both exit ports  32 . 2 ,  32 . 3  feed into a single scroll of the turbocharger  54 , whereas in the case of a dual turbo exit port  32 . 2  feeds a first scroll and exit port  32 . 3  feeds a second scroll of the turbocharger  54 . The outlet  56  from turbocharger  54  is coupled to a tailpipe which directs the exhaust gases to the catalytic convertor (not shown). 
     The embodiment illustrated in  FIGS. 1-3  show a four-cylinder engine  10  with the partially integrated exhaust manifold  28 . The first exhaust leg  30 . 1  has a pair of ducts  58 . 1 ,  58 . 2  that are manifolded into a single exhaust passageway  60  for cylinder  14 . 1  that terminates at exit port  32 . 1 . The second exhaust leg  30 . 2  has a pair of ducts  62 . 1 ,  62 . 2  that are manifolded into a single exhaust passageway  64  for cylinder  14 . 2  and a pair of ducts  66 . 1 ,  66 . 2  that are manifolded into a single exhaust passageway  68  for cylinder  14 . 3 . Exhaust passageways  64  and  68  are manifolded together at exit port  32 . 2 . The third exhaust leg  30 . 3  has a pair of ducts  70 . 1 ,  70 . 2  that are manifolded into a single exhaust passageway  72  for cylinder  14 . 4  that terminates at exit port  32 . 3 . 
     The embodiment illustrated in  FIG. 4  shows a three-cylinder configuration  110  with the partially integrated exhaust manifold  128 . The first exhaust leg  130 . 1  has a pair of ducts  158 . 1 ,  158 . 2  that are manifolded into a single exhaust passageway  160  for cylinder  114 . 1  that terminates at exit port  132 . 1 . An inlet  140  of the control valve  138  is in fluid communication with the first leg  130 . 1 . One outlet  142  of the control valve  138  is in fluid communication with intake ports  122  via the EGR valve  139  and enables dedicated exhaust gas recirculation from the exhaust side of one cylinder  114 . 1  to the intake side of all four cylinders  114 . 1 - 114 . 4 . Another outlet  144  of the control valve  138  is coupled to the exhaust system upstream of a catalytic converter (not shown). 
     The second exhaust leg  130 . 2  has a pair of ducts  162 . 1 ,  162 . 2  that are manifolded into a single exhaust passageway  164  for cylinder  114 . 2  and a pair of ducts  166 . 1 ,  166 . 2  that are manifolded into a single exhaust passageway  168  for cylinder  114 . 3 . Exhaust passageways  164  and  168  are manifolded together at exit port  132 . 2 . The partially integrated manifold  128  illustrated in  FIG. 4  could be used for an inline three-cylinder engine or alternately for each bank of cylinders in a V-6 engine configuration. 
     The embodiment illustrated in  FIG. 5  show an inline six-cylinder engine  210  with the partially integrated exhaust manifold  228 . The first exhaust leg  230 . 1  has a pair of ducts  258 . 1 ,  258 . 2  that are manifolded into a single exhaust passageway  260  for cylinder  214 . 1  that terminates at exit port  232 . 1 . The second exhaust leg  230 . 2  has a pair of ducts  266 . 1 ,  266 . 2  that are manifolded into a single exhaust passageway  268  for cylinder  114 . 2  and a pair of ducts  270 . 1 ,  270 . 2  that are manifolded into a single exhaust passageway  272  for cylinder  214 . 3 . Exhaust passageways  268  and  272  are manifolded together at exit port  232 . 2 . The third exhaust leg  230 . 3  has a pair of ducts  270 . 1 ,  270 . 2  that are manifolded into a single exhaust passageway  272  for cylinder  214 . 4 , and a pair of ducts  274 . 1 ,  274 . 2  that are manifolded into a single exhaust passageway  276  for cylinder  214 . 5 . Exhaust passageways  272  and  276  are manifolded together at exit port  232 . 3 . A fourth exhaust leg  230 . 4  has a pair of ducts  278 . 1 ,  278 . 2  that are manifolded into a single exhaust passageway  280  for cylinder  114 . 6 . Exhaust passageway  280  is manifolded into exhaust passageway  260 . An inlet  240  of the control valve  238  is in fluid communication with the exhaust passageway  260 . One outlet  242  of the control valve  238  is in fluid communication with intake ports  222  via the EGR valve  239  and enables dedicated exhaust gas recirculation from the exhaust side of two cylinders  214 . 1 ,  214 . 6  to the intake side of all six cylinders  214 . 1 - 214 . 6 . Another outlet  244  of the control valve  238  is coupled to the exhaust system upstream of a catalytic converter (not shown). 
     The foregoing description of embodiments has been provided for purposes of illustration and to aid in an understanding of this disclosure. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described in that manner. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.