Patent Publication Number: US-6213074-B1

Title: Internal combustion engine with wedge-shaped cylinder head and integral intake manifold and rocker cover therefor

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is generally directed toward internal combustion engines and, more specifically, to an internal combustion engine having a V-shaped engine block, wedge-shaped cylinder head and a single, integrated intake manifold and rocker cover. 
     2. Description of the Related Art 
     Internal combustion engines known in the related art may include, among other basic components, a cast engine block having a pair of cylinder banks arranged in a V-shaped configuration, a pair of cylinder heads associated with each cylinder bank mounted to the engine block and a pair of valve covers fastened to each cylinder head. Each bank of cylinders is usually serviced by a dedicated intake manifold mounted to each cylinder head. A plurality of pistons are reciprocated in cylinders formed in each cylinder bank of the engine block. Similarly, a plurality of valves supported in each cylinder head are opened and closed via rocker arms, cams or some other mechanism to provide fluid communication between the cylinders and intake and exhaust manifolds. Fuel is combusted within the cylinders to reciprocate the pistons which, in turn, act on a crankshaft from which power may be translated to drive an automotive vehicle or any number of other devices. 
     In the case of compression ignition or diesel engines, the fuel/air mixture is delivered at relatively high pressures via fuel injector assemblies. Presently, conventional injectors are delivering this mixture at pressures as high as 32,000 psi. These are fairly high pressures and have required considerable engineering attention to a number of engine components to ensure the structural integrity, good sealing properties and the effective atomization of the fuel within the combustion chamber. 
     In addition, modern, high speed, direct injection diesel engines often employ cylinder heads having four valves per cylinder to meet challenging performance, noise and emission targets. However, four-valve configurations typically present difficult packaging challenges for small bore, direct injection, diesel engines. As higher engine efficiencies are targeted, engine designers are pushing engines to achieve higher peak firing pressures, necessitating higher head bolt clamp loads. This requirement further complicates the cylinder head and intake port packaging approach. 
     Many diesel engines adapted for automotive applications in North America will require lower valve train costs to compete effectively with gasoline engines. This factor, among other things, has resulted in the use of an overhead valve (OHV) configuration in the cylinder head, rather than the more generally accepted single overhead camshaft (SOHC) or dual overhead cam shaft (DOHC) design. Especially when employed in connection with V-block engines, overhead valve configurations achieve the necessary automotive diesel-rated speeds with sufficient valve train stiffness, while at the same time resulting in lower overall costs. Further, overhead valve configurations reduce total friction when compared with single or double overhead cam configurations. However, engines which employ overhead valve configurations also require push rods to actuate the valve rocker. Push rods present an additional space claim in the already crowded cylinder head envelope. 
     In essence, then, the modem diesel engine must provide a substantial fuel economy advantage while meeting evermore stringent emission regulations which are imposed on smaller, more compact diesel engines. However, increasing demands for greater fuel economy, cleaner burning, fewer emissions, NO x  and noise control in addition to better component packaging, have placed, and will continue to place, even higher demands on the engine. Thus, there is an ongoing need in the art for better control over these various parameters in a cost-effective manner. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes these disadvantages in the related art in an internal combustion engine including an engine block having a pair of cylinder banks arranged in a V-shaped configuration. Each of the pair of cylinder banks presents a top wall disposed at an acute angle relative to the horizontal and plurality of cylinders disposed spaced from one another and longitudinally aligned within each cylinder bank. A pair of cylinder heads are associated with each pair of cylinder banks. Each of the cylinder heads includes upper and lower walls disposed at an angle relative to each other such that each cylinder head is substantially wedge-shaped in cross-section. The cylinder heads are mounted to the engine block such that the lower wall of each cylinder head seals the opposing top wall of the associated cylinder bank and closes the open ends of the cylinders and such that the upper wall of each cylinder head is substantially parallel to the horizontal. A pair of exhaust manifolds are mounted to each of the pair of cylinder heads. A single, integrated intake manifold and rocker cover is mounted to the horizontal upper walls of the cylinder heads. The integrated manifold and rocker cover provides intake air to the cylinders in each of the cylinder banks through the cylinder heads and recirculates exhaust gas from the exhaust manifold to each of the cylinders in the cylinder banks. 
     The present invention facilitates efficient engine component packing objectives by combining a single intake manifold for servicing both cylinder banks with a single rocker cover. Accordingly, the present invention eliminates the need for separate intake manifolds, gaskets, exhaust gas recirculation (EGR) cooler housings and certain on-board plumbing associated with externally mounted EGR valves. Further, the use of a wedge-shaped cylinder head design for a V-block engine provides a substantially horizontal mounting face for the single, integrated intake manifold and rocker cover. With this design, the intake manifold supplies intake air to the cylinders from above. Further, the wedge-shaped cylinder head provides vertical access into the intake port of the cylinder. 
     Accordingly, one advantage of the present invention is that it eliminates a number of components as well as plumbing, gaskets, brackets and fasteners associated with separate intake manifolds for each cylinder head, separate rocker covers and EGR cooling apparatuses. 
     Another advantage of the present invention is that the wedge-shaped cylinder heads present a substantially horizontal mounting surface for the intake manifold. This feature reduces stack up variability and avoids side loads on the cylinder head and block. 
     Still another advantage of the present invention is that the wedge-shaped cylinder heads provide added flexibility to optimize intake port geometry with a low loss top entry intake port. Further, vertical intake air entry into the cylinder head may be used to achieve additional tumble within the combustion chamber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
     FIG. 1 is a top view of the V-block internal combustion engine of the present invention. 
     FIG. 2 is a cross-sectional side view of a V-block internal combustion engine including wedge-shaped cylinder heads and a single, integrated intake manifold and rocker cover taken substantially along lines  2 — 2  of FIG.  1 . 
     FIG. 3 is a cross-sectional side view of a V-block internal combustion engine including wedge-shaped cylinder heads and a single, integrated intake manifold and rocker cover taken substantially along lines  3 — 3  of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     Referring now to FIGS. 1 and 2, an internal combustion engine is generally indicated at  10 . In the preferred embodiment, the engine  10  is a compression ignition, or diesel engine, but those having ordinary skill in the art will appreciate that the engine  10  may also be a spark ignition engine. The engine  10  includes a cast engine block  12  having a pair of cylinder banks  14 ,  16  arranged in a V-shaped configuration so as to define a valley or plenum  18  therebetween. Because of this V shape, each of the cylinder banks  14 ,  16  present a top wall or “fire deck”  20 ,  22 , respectively, which is disposed at an acute angle relative to a horizontal plane when viewed in cross-section as shown in FIGS. 2 and 3. Further, each cylinder bank  14 ,  16  includes a plurality of open-ended cylinders  24  disposed spaced from one another and longitudinally aligned within each cylinder bank  14 ,  16 . 
     A piston  26  is reciprocally supported in each of the cylinders  24 . Each piston  26  is connected by a connecting rod  28  to a crankshaft (not shown) journaled in a conventional fashion in the lower portion of the cylinder block  12 . Fuel is combusted within the cylinders  24  which reciprocates the pistons  26  which, in turn, act on the crankshaft from which power may be translated to drive an automotive vehicle, or any number of other devices. An oil pan  30  is secured below the engine block  12  and provides a sump for oil used in lubricating the various parts of the engine. An oil filter  32  is mounted to the engine block  12  to filter contaminants which are picked up by the oil during lubrication. 
     As best shown in FIGS. 2 and 3, a pair of cylinder heads, generally indicated at  34  and  36 , are associated with the pair of cylinder banks  14 ,  16 , respectively. Each of the cylinder heads  34 ,  36  include upper and lower walls  38 ,  40 . The upper and lower walls  38 ,  40  are disposed at angles relative to each other such that each cylinder head  34 ,  36  is substantially wedge-shaped in cross-section. Furthermore, each cylinder head  34 ,  36  includes inner and outer side walls  42 ,  44 , respectively, and front and rear walls (not indicated by reference numerals) which extend between the inner and outer side walls  42 ,  44 . The inner and outer walls  42 ,  44 , as well as the front and rear walls all extend between the upper and lower walls  38 ,  40 . 
     The cylinder heads  34 ,  36  are mounted to the engine block  12  such that the lower wall  40  of each of the cylinder heads  34 ,  36  seals the opposing top wall  20 ,  22  of the associated cylinder bank  14 ,  16  so as to close the open end of the cylinders  24 . Furthermore, the cylinder heads  34 ,  36  are mounted to the engine block  12  such that the upper wall  38  of each of the cylinder heads  34 ,  36  is substantially parallel to a horizontal lane when viewed in cross-section as shown in FIGS. 2 and 3. 
     The walls  38 - 44  and front and rear walls enclose a coolant jacket adapted to receive liquid coolant for cooling the various parts of each cylinder head  34 ,  36 . For each cylinder location, the cylinder heads  34 ,  36  carry a number of components including, for example, an injector, intake and exhaust valves associated with the intake ports  50  and exhaust ports  52  (FIG. 1) as well as rocker arms used to move the intake and exhaust valves to open the intake ports  50  and exhaust ports  52 . The rocker arms are actuated by push rods connected with spring-biased followers which engage cams on cam shafts driven via other related components by the crankshaft, all of which are conventional and not shown here. Further, the engine  10  also includes a number of other conventional components which are commonly known in the art and will not be described in detail here. 
     The internal combustion engine  10  also includes a pair of exhaust manifolds  54 ,  56  mounted to the outer side walls  44  of each of the pair of cylinder heads  34 ,  36 . A single, integrated intake manifold and rocker cover, generally indicated at  58 , is mounted to the horizontal upper walls  38  of the pair of cylinder heads  34 ,  36  and spans the plenum  18  defined by the V-shaped pair of cylinder banks  14 ,  16 . The integrated manifold and rocker cover  58  provides intake air to the cylinders  24  in each of the pair of cylinder banks  14 ,  16  through the pair of cylinder heads  34 ,  36 . Furthermore, the integrated manifold and rocker cover  58  also recirculates exhaust gas from the pair of exhaust manifolds  54 ,  56  to each of the cylinders  24  in the cylinder banks  14 ,  16 . To this end, the integrated manifold and rocker cover  58  includes an exhaust gas recirculating (EGR) cooler core, generally indicated at  60 , which is removably mounted centrally therein and in fluid communication with the exhaust manifolds  54 ,  56  via delivery passages  59  located at the upper end of the top view of FIG. 1, for cooling the exhaust gas before it is delivered to the cylinders  24 . The EGR cooler core  60  may also include EGR valves, schematically represented at  61  in FIG. 2, and possibly other related components which are not shown. As best shown in FIG. 1, the cylinder heads  34 ,  36  also include coolant connections  62  interconnecting the coolant jacket (not shown) in the cylinder heads with the EGR cooler core  60 . Similarly, the integrated manifold and rocker cover  58  includes coolant passages  64  which communicate between the coolant connections  62  and the EGR cooler core  60 . The coolant connections  62  and coolant passages  64  may be located opposite the delivery passages  59 , as viewed in FIG.  1 . 
     The integrated manifold and rocker cover  58  also includes a plurality of EGR introduction passages  66  spaced relative to one another and on either side of the EGR cooler core  60 . The introduction passages  66  provide fluid communication between the EGR cooler core  60  and a pair of rail manifolds  67  formed in the integrated manifold rocker cover  58  on either side of the EGR cooler core  60 . The rail manifolds  67  provide fluid communication between ambient intake air, the EGR cooler core  60  and the intake ports  50  formed in the cylinder heads  34 ,  36  via intake passages  70 . Exhaust passages  72  (FIG. 1) provide fluid communication between the exhaust port  52  and the exhaust manifolds  54 ,  56 . 
     As illustrated in FIGS. 2 and 3, the integrated intake manifold and rocker cover  58  may also include cooling fins  74  formed on the outer surface thereof to assist in cooling the exhaust gas flowing through channels  76  formed in the manifold (FIG.  2 ). Further, the coolant connections  62 , coolant passages  64 , as well as the EGR introduction passages  66  act to minimize noise transmission from the engine to the environment. 
     The present invention facilitates efficient engine component packaging objectives by combining a single intake manifold  58  for servicing both cylinder banks  14 ,  16 , with a single rocker cover. Accordingly, the present invention eliminates the need for separate intake manifolds, gaskets, EGR cooler housing and certain on-board plumbing associated with externally mounted EGR valves. Further, use of wedge-shaped cylinder heads  34 ,  36  for a V-block engine provide a substantially horizontal mounting face for the single, integrated intake manifold and rocker cover  58 . This structure facilitates the supply of intake air through the intake manifold  58  from above. Further, the wedge-shaped cylinder heads  34 ,  36  provide vertical access to the intake ports  50  of each cylinder  24 . Finally, the integrated intake manifold and rocker cover may be manufactured from a number of materials including aluminum, cast-iron, and even thermoplastics. 
     Thus, the present invention eliminates a number of components as well as plumbing, gaskets, brackets and fasteners associated with separate intake manifolds for each cylinder head, separate rocker covers and EGR cooling apparatuses. Further, the wedge-shaped cylinder heads  34 ,  36  also provide added flexibility to optimize intake port geometry with a low loss, top entry intake port  50 . Vertical intake air entry into the cylinder heads  34 ,  36  may be used to achieve additional tumble within the combustion chamber. 
     The invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. 
     Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.