Patent Publication Number: US-7900593-B2

Title: Thermal and acoustic valley shield for engine assembly

Description:
CLAIM OF PRIORITY 
     This application claims priority to U.S. Provisional Patent Application No. 60/956,029, filed on Aug. 15, 2007, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to internal combustion engines, and more particularly to thermal valley shields for V-type engine block assemblies having an interbank valley defined between the two engine cylinder banks. 
     BACKGROUND OF THE INVENTION 
     “V-type” internal combustion engine (ICE) assemblies are traditionally defined by an engine block having a pair of outwardly angled cylinder banks with inside walls that define an interbank valley therebetween. Each cylinder bank of a typical V-type over-head valve ICE defines a cylinder bore having a piston reciprocally movable therein. The piston and cylinder bore cooperate with a portion of a cylinder head to form a variable volume combustion chamber. The cylinder head defines intake ports through which air, provided by an intake manifold, is selectively introduced into the combustion chamber. Additionally, the cylinder head defines exhaust ports through which exhaust gases or products of combustion are selectively evacuated from the combustion chamber. Normally, an exhaust manifold is affixed to the cylinder head, by bolting or other fastening means, such that the exhaust manifold communicates with each exhaust port to carry the exhaust gases from the ICE to a vehicular exhaust aftertreatment system for subsequent release to the atmosphere. 
     In-cylinder emissions reduction devices, such as exhaust gas recirculation (EGR) systems, are also included in many current engine assemblies in order to curtail the amount of NOx and other pollutants from the exhaust gas released into the atmosphere. EGR works by recirculating a portion of an engine&#39;s exhaust gas back to the engine cylinders. Recirculation affects the engine&#39;s combustion process in three primary ways. First, there is a dilution effect caused by the reduction in the concentration of oxygen in intake air. Second, there is a thermal effect caused by increasing the specific heat capacity of each charge. Third, there is a chemical effect which results from the dissociation of CO2 and water vapor during combustion. EGR can be achieved by either recirculating some of the exhaust leaving the engine back into the engine, which is known as external EGR, or by retaining a fraction of the exhaust gas—i.e., gas never leaves the engine, which is known as internal EGR. Major exhaust gas constituents that are “recirculated” include N2, CO2, water vapor, and partially burned hydrocarbons. 
     Some modern ICEs employ a mechanical supercharging device such as a turbocharger, which is short for turbine driven, forced induction supercharger. Most turbochargers include a turbine portion and a compressor portion. The turbine portion has a turbine housing that is in fluid communication at an inlet end with the engine exhaust manifold. The turbine housing receives exhaust gases from the exhaust manifold, and redirects the exhaust stream to spin a turbine blade. The turbine blade is rigidly mounted to a compressor blade for unitary rotation therewith. As the compressor blade spins, ambient air is compressed within a compressor housing; the compressed air is subsequently introduced to the intake manifold to increase the volumetric efficiency of the ICE. 
     To maximize the performance of the turbocharger, the turbine housing is typically located as close to the exhaust port as possible so that heat energy from the flowing exhaust stream that might otherwise be used to spin the turbine blade is not wasted through radiation to the atmosphere. Consequently, when a turbocharger is attached to a V-type ICE, the turbocharger is often mounted immediately adjacent to the valley, between the two cylinder banks of the engine block, to minimize the distance of travel of the exhaust stream, and to maximize use of the space between the banks. In this type of arrangement, the turbocharger is often surrounded by a protective jacket (commonly referred to as a valley shield or acoustic pad) in order to minimize undesirable radiation of heat and noise generated by engine components, such as, for example, the exhaust manifold, and also to maintain the energy content of the exhaust gases. 
     SUMMARY OF THE INVENTION 
     The valley shields of the present invention are operable to act as a noise, fluid, and heat barrier between an internal combustion engine assembly and engine components positioned on an opposing side of the valley shield. The valley shields of the present design offer, among other things, improved acoustic damping performance, increased thermal resiliency and protective capacity, and improved vibration attenuation. In addition, the present design also offers enhanced fluid drainage characteristics with minimal fluid absorption, while allowing for more efficient packaging and ease of installation of the valley shield during engine assembly. 
     According to one embodiment of the present invention, a valley shield is provided for use with an engine assembly. The engine assembly includes an engine block with first and second cylinder banks that define an interbank valley therebetween. The engine assembly also includes first and second cylinder heads respectively secured adjacent the first and second cylinder banks. The valley shield includes a unitary body with a base portion having first and second laterally spaced side portions extending angularly outward therefrom. The base portion of the valley shield is oriented proximate to the interbank valley, and is preferably contoured to define an air pocket therebetween. The unitary body is configured to pressably fit into place proximate to the interbank valley between the first and second cylinder banks. As such, the unitary body may be characterized by an absence of structure that is configured to receive a bolt, a fastener, a screw, or other means for attaching the unitary body to the engine block. 
     According to one aspect of the present invention, the two laterally spaced side portions extend from the base portion at a first angle, whereas the first and second cylinder banks extend from the engine block at a second angle that is less than the first angle, thereby providing the abovementioned press fit when the valley shield is properly mated with the engine block. In this instance, the unitary body is preferably locked into place adjacent the interbank valley by one or both of the first and second cylinder heads and the engine block sealing flange. Ideally, the valley shield is nestably positioned immediately adjacent to the interbank valley—i.e., there being no structure between the interbank valley and the valley shield. 
     According to another aspect of the present invention, the first and second laterally spaced side portions respectively include first and second flange portions extending laterally outward therefrom. The first and second flange portions are configured to directly engage with or abut against the outer perimeter of the interbank valley, and thereby provide an acoustic seal therebetween. For example, each of the flange portions has a laterally oriented outer edge with a substantially identical contour as that segment of the interbank valley perimeter respectively engaged by that particular outer edge. In addition, the first and second laterally spaced side portions preferably each consist of first, second and third wall members coplanar to and longitudinally displaced from one another. In this instance, the entire perimeter of the unitary body is preferably contoured to match the geometric configuration of the interbank valley and first and second cylinder banks. 
     According to yet another aspect of the present invention, the body of the valley shield includes a first layer made of a heat resistant material that is operable to reflect radiant heat, such as, but not limited to, aluminum or steel foil. In addition, the valley shield also includes a second layer made of an acoustic absorbing material having a first density, such as, but not limited to, compressed particle board. Also included is a third layer made of a fluid resistant material having a second density, such as, but not limited to, a melamine foam and powder composite. 
     According to yet another aspect of the present invention, the base portion includes one or more, preferably longitudinally displaced trough portions each defining one or more drain holes therethrough. Desirably, the diameter of each of the first and second drain holes is sufficiently sized to prevent surface tension from hindering fluid flow. In addition, each trough portion extends downwardly from the base portion to allow for gravitational evacuation of fluid therefrom. For example, the various trough drains holes are preferably positioned as the vertically lowest portion of the unitary body relative to the interbank valley. It is further preferred that each trough portion be configured to direct fluid away from the base portion, through the drain holes, towards a fluid drainage port provided in the interbank valley. 
     According to another embodiment of the present invention, a valley shield is provided for use with an internal combustion engine assembly. The engine assembly includes an engine block having first and second cylinder banks outwardly oriented with respect to one another such that they form an angle of less than 180 degrees, and thereby define a generally V-shaped interbank valley therebetween. The ICE assembly also includes first and second cylinder heads respectively secured adjacent the first and second cylinder banks. 
     The valley shield has a unitary body including a base portion with first and second laterally spaced side portions extending angularly outward therefrom. The unitary body is configured to pressably fit into place immediately adjacent the interbank valley between the first and second cylinder banks, and at least partially secure therein by one or more of the cylinder heads. Each laterally spaced side portion includes a respective flange portion that extends laterally outward therefrom. Each flange portion is configured to directly engage with a perimeter of the interbank valley to provide an acoustic seal therebetween. The base portion includes first and second longitudinally displaced trough portions each defining one or more drain holes therethrough. The trough portions are configured to allow for gravitational evacuation of fluid therefrom. 
     According to yet another embodiment of the present invention, an internal combustion engine assembly is provided. The engine assembly includes an engine block having first and second cylinder banks outwardly oriented with respect to one another such that they form an angle of less than 180 degrees, and thereby define a generally V-shaped interbank valley therebetween. First and second cylinder heads are respectively secured adjacent the first and second cylinder banks. In addition, an exhaust manifold is integrally formed with one of the cylinder heads, and oriented adjacent to the interbank valley. A turbocharger, operable to receive exhaust gases from the exhaust manifold, is positioned proximate to the interbank valley. An exhaust gas recirculation system, including a flow control valve and a cooler unit with at least one coolant intake hose and least one coolant output hose, is at least partially nested within the interbank valley. 
     The internal combustion engine assembly also includes a valley shield interspersed between the interbank valley and the turbocharger or the exhaust gas recirculation system. The valley shield is contoured to define an air pocket between the interbank valley and the turbocharger or the exhaust gas recirculation system. The valley shield has a unitary body including a base portion with first and second laterally spaced side portions extending angularly outward therefrom. The unitary body is configured to pressably fit into place immediately adjacent the interbank valley between the first and second cylinder banks, and be at least partially secured therein by one or both of the cylinder heads. The first and second laterally spaced side portions respectively include first and second flange portions extending laterally outward therefrom. Each flange portion is configured to directly engage with the perimeter of the interbank valley to thereby provide an acoustic seal therebetween. The base portion includes one or more trough portions, each defining at least one drain hole therethrough. Each trough portion extends downwardly from the base portion to allow for gravitational evacuation of fluid therefrom. 
     The above features and advantages, and other features and advantages of the present invention will be readily apparent from the following detailed description of the preferred embodiments and best modes for carrying out the present invention when taken in connection with the accompanying drawings and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective illustration of a portion of an exemplary internal combustion engine assembly having nested therein a valley shield in accordance with a preferred embodiment of the present invention; 
         FIG. 2  is a perspective illustration of the valley shield of  FIG. 1 ; 
         FIG. 2A  is a cross-sectional view of a portion of the valley shield taken along line  2 - 2  of  FIG. 2 ; 
         FIG. 3A  is a front cross-sectional view of the internal combustion engine assembly taken along line  1 - 1  of  FIG. 1 ; and 
         FIG. 3B  is a plan perspective illustration of the internal combustion engine assembly of  FIG. 1  with certain components removed to more clearly illustrate the perimeter sealing, nest fit between the valley shield and engine block. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the Figures, wherein like reference numbers refer to the same or similar components throughout the several views, there is shown in  FIG. 1  an internal combustion engine assembly, presented herein in an exemplary embodiment as a four-stroke cycle, turbocharged and intercooled diesel engine, indicated generally at  10 . The engine assembly  10  includes a turbocharger device  20  and exhaust gas recirculation (EGR) system  30  in operative communication therewith. Notably, the engine  10 , turbocharger  20 , and EGR system  30  shown in  FIG. 1  have been greatly simplified, it being understood that further information regarding such systems may be found in the prior art. Furthermore, it should be readily understood that  FIG. 1  is merely a representative application by which the present invention may be practiced. As such, the present invention is by no means limited to the particular engine configuration of  FIG. 1 . Finally, the drawings presented herein, i.e.,  FIGS. 1 through 3B , are not to scale and are provided purely for instructional purposes. Thus, the particular dimensions of the drawings presented herein are not to be considered limiting. 
     The engine assembly  10  includes an engine block  12  with a generally “V-type” configuration. In a V-type configuration, the engine block  12  includes a left and a right bank of cylinder bores, referred to hereinafter as first and second cylinder banks  14 A and  14 B, respectively, outwardly oriented with respect to one another at an included angle (such as second angle  72  of  FIG. 3A ) of less than 180 degrees to define an interbank valley  60  therebetween. Each of the first and second cylinder banks  14 A,  14 B defines one or more piston cylinder bores, identified throughout the FIGS. by reference numeral  16 . To this regard, the internal combustion engine  10  may operate, for example, in a compression ignited or spark ignited combustion mode. 
     The turbocharger, which is depicted schematically herein at  20 , is in fluid communication with both the engine block  12  and the EGR system  30 . The turbocharger  20  includes a turbine portion (not shown) with a turbine housing in fluid communication with the engine exhaust manifold (not shown). The turbine housing receives exhaust gases from the exhaust manifold, and redirects the exhaust stream to a compressor housing (not shown) for condensing ambient air therein. The compressed air is subsequently introduced to the intake manifold to increase the volumetric efficiency of the engine assembly  10 . The engine assembly  10  may incorporate a single turbocharger device (as discussed herein), twin turbochargers, or staged turbochargers, without departing from the intended scope of the present invention. 
     The EGR system  30  is partially depicted in  FIG. 1  by an EGR cooler  32  and EGR flow control valve  34 . The EGR flow control valve  34  is upstream of the EGR cooler  32 , and adapted to control the amount of exhaust gas that is recycled through the engine assembly  10 . The EGR cooler  32  is operable to receive coolant (not shown) from a coolant intake hose  36  to cool exhaust gas circulating proximal thereto (e.g., through convective heat transfer). The coolant is thereafter evacuated from the EGR cooler  32  through a coolant output hose  38  to a heat sink (not shown) in order to be recycled through the engine assembly  10 . The EGR system  30  is operable to selectively recirculate a predetermined volume of the exhaust gas produced by the engine assembly  10  back to the piston cylinder bores  16 . 
     Looking now to  FIG. 3A , first and second cylinder heads  18 A and  18 B, respectively, are mounted to a respective one of the first and second cylinder banks  14 A,  14 B. A piston  22  is reciprocally positioned within each piston cylinder bore  16 . A variable volume combustion chamber  24  is defined between the pistons  22  and cylinder heads  18 A,  18 B. Each of the first and second cylinder heads  18 A,  18 B define a plurality of exhaust ports  26 A,  26 B, respectively, through which exhaust gases or products of combustion (e.g., nitrogen oxide, nitrogen dioxide, etc.) are selectively evacuated from the respective cylinder bore  16 . The exhaust ports  26 A,  26 B communicate exhaust gases to a respective integral exhaust manifold (not shown), also defined within the first and second cylinder heads  18 A,  18 B. Intake manifolds (not shown) distribute air to one of a plurality of intake runners (not shown), each of which is in fluid communication with a respective one of a plurality of intake ports, such as first and second intake ports  28 A and  28 B, respectively, defined by the first and second cylinder heads  18 A,  18 B. The intake ports  28 A,  28 B are adapted to selectively introduce air into one of the plurality of piston cylinder bores  16  where it, along with a fuel charge, is subsequently combusted in a known fashion. 
     As shown in  FIG. 3A , the V-shaped interbank valley  60  includes first and second laterally opposed bank portions  62  and  64 , respectively, and an intermediate, bottom portion  66  therebetween. The first and second integral exhaust ports  26 A,  26 B are positioned with respect to the cylinder block  12  such that they discharge exhaust gases in an inboard configuration. Specifically, the first and second integral exhaust ports  26 A,  26 B are substantially adjacent to an inboard region of the engine assembly  10 , proximal to the generally interbank valley  60 . The inboard discharge configuration is beneficial in that the packaging requirement of the engine  10  may be reduced. However, the first and second exhaust ports  26 A,  26 B and first and second intake ports  28 A,  28 B may operate in any orientation within the general area defined by the cavity  60  without departing from the scope of the present invention. 
     According to the embodiment of  FIG. 1 , a valley shield  40 , also referred to herein as a valley barrier or acoustic pad, is shown nestably positioned substantially inside the interbank valley  60 . As best seen in  FIGS. 2 and 3B , the valley shield  40  includes a unitary body  42 , elongated in a longitudinal direction of the engine assembly  10 . Ideally, the unitary body  42  is a one-piece member. However, it is also within the scope of the claimed invention that the unitary body  42  be fabricated as multiple segments. 
     Referring to  FIG. 2 , the unitary body  42  includes a base portion  44  with a recessed stratum  46 . First and second laterally spaced side portions  50 A and  50 B, respectively, extend angularly outward from the base portion  44  in a generally obtuse oblique manner. The first laterally spaced side portion  50 A includes first, second and third wall members  54 A,  56 A and  58 A, respectively, which are coplanar with and longitudinally displaced from one another. Similarly, the second laterally spaced side portion  50 B includes first, second and third wall members  54 B,  56 B and  58 B, respectively, which are coplanar with and longitudinally displaced from one another. The base portion  44  of the valley shield  40  is oriented immediately adjacent to the bottom portion  66  of the interbank valley  60 —i.e., there being no structure between the valley shield  40  and the interbank valley  60 , and is contoured to define an air pocket  61  therebetween. 
     The first and second laterally spaced side portions  50 A,  50 B include first and second flange portions  52 A and  52 B, respectively, extending laterally outward therefrom. As best seen in  FIGS. 3A and 3B , the first and second flange portions  52 A,  52 B are configured to directly engage (e.g., come into hard contact) with an outer perimeter  68  of the interbank valley  60  to provide an acoustic seal therebetween. More specifically, each of the first and second flange portions  52 A,  52 B has an outer edge with substantially the same contour (i.e., geometrically coextensive) as that portion of the perimeter  68  of the interbank valley  60  respectively engaged by that flange, as best seen in  FIG. 3B . Ideally, the perimeter  43  of the entire unitary body  42  is contoured or shaped to match the geometric configuration of the interbank valley  60  and first and second cylinder banks  18 A,  18 B. 
     Looking now to  FIG. 2A , a cross-sectional view of a portion of the valley shield  40  is provided, taken along line  2 - 2  of  FIG. 2 . The valley shield  40  is a multi-layered composite or laminate structure, including first, second, and third layers  80 ,  82  and  84 , respectively, and a fluid resistant (e.g., non-absorbent) scrim jacket  86 A-B. As shown in  FIG. 2A , the first layer  80  is intended as the top most layer of the unitary body  42  (i.e., most distal layer relative to the engine block  12 ). The first layer  80  is a fluid resistant, reflective material, such as, but not limited to, aluminum or steel foil, operable to deflect radiant heat produced by the EGR cooler  32  and, through the addition of optional micro-perforations (not shown), for enhanced acoustic absorption. The first layer  80  is secured, adhered, or attached, e.g., via an adhesive (not shown), to an upper portion of the fluid resistant scrim jacket  86 A-B, referred to hereinafter as the first scrim layer  86 A. The second and third layers  82 ,  84  are encased by or sandwiched within the fluid resistant scrim jacket  86 A-B. In other words, the second and third layers  82 ,  84  are disposed between the first scrim layer  86 A, and a lower portion of the fluid resistant scrim jacket  86 A-B, referred to hereinafter as the second scrim layer  86 B, which is intended as the bottom most, engine-side layer. The second layer  82  is made of a first material having a first density, whereas the third layer  84  is made of a second material having a second density. More specifically, the second layer  82  is intended to be a high density, acoustic barrier, fabricated from, for example, but not limited to, compressed particle board. Contrastingly, the third layer  84  is intended to be a lower density, fluid resistant layer, fabricated from, for example, but not limited to, a melamine foam impregnated with a talcum based powder. Recognizably,  FIG. 2A  is an illustration provided herein for explanation and clarification purposes and is in no way intended as limiting. 
     Looking now at  FIG. 3A , the unitary body  42  is nestably positioned proximate to the interbank valley  60 , adjacent to bank portions  62  and  64  and bottom portion  66 , between the first and second cylinder banks  14 A,  14 B and the first and second cylinder heads  18 A,  18 B. The unitary body  42  is operatively configured to pressably fit or “snap” into place adjacent the interbank valley  60  between the first and second cylinder banks  14 A,  14 B, and be securably locked therein by the first and second cylinder heads  18 A,  18 B and the engine block sealing flange  48 . For example, the first and second laterally spaced side portions  50 A,  50 B extend from the base portion  44  of the unitary body  42  at a first angle  70  ( FIG. 2 ), whereas the first and second cylinder banks  14 A,  14 B extend from the engine block  12  at a second angle  72  ( FIG. 3A ). The first angle  70  is greater than the second angle  72  such that the valley shield  40  is slightly wider than the interbank valley  60 . Once pressed into the interbank valley  60 , the extra width and elastic nature of the unitary body  42  will tend to push the valley shield  40  upward against the first and second cylinder heads  18 A,  18 B and the engine block sealing flange  48 , thus retaining the valley shield in its nested position therebetween. Accordingly, the unitary body  42  may be characterized by an absence of structure configured to receive any means solely intended to fasten the valley shield  40  to the engine block  12 , such as, by way of example, bolts, bosses, fasteners, and screws (none of which are depicted herein). Additional benefits of this particular configuration is that upwardly biasing motion created by the extra width and elastic nature of the unitary body  42  is to enlarge the size (i.e., volume) of the air pocket  61 , providing for better acoustic absorption, and minimizing hard contact area with the engine block  12 , thereby reducing or eliminating conductive heat transfer therebetween. Of paramount importance, a valley shield  40  of the present design may be readily installed early in the engine build process with minimal labor and effort, as the present configuration will allow the valley shield  40  to be retained during any subsequent engine build operations. 
     Turning back to  FIG. 2 , the recessed stratum  46  of the body base portion  44  defines one or more advanced “drainback” features, defined herein by first and second longitudinally displaced trough portions  74  and  76 , respectively. The first trough portion  74  includes a first stepped surface  71  connected to the recessed stratum  46  via first peripheral trough wall  73  and first inclined surface  75 . Similarly, the second trough portion  76  includes a second stepped surface  77  connected to the recessed stratum  46  via second peripheral trough wall  78  and second inclined surface  79 . The one or more advanced “drainback” features, i.e., trough portions  74 ,  76 , each respectively defines one or more drainage holes, such as first and second drain holes  92 ,  94  of  FIG. 2 . The number of drainage holes, and diameter of each drainage hole, such as first and second drain holes  92 ,  94 , should be properly configured to maintain proper acoustic sealing. Contrastingly, the diameter of each drainage hole, such as first and second drain holes  92 ,  94 , is sufficiently sized to prevent surface tension from hindering fluid flow during evacuation. 
     Pooling of fluid (not shown) in the valley shield  40  due to the “tub” shape of the unitary body  42  is minimized or eliminated through the present design. Specifically, an oil drainage port or hole  90  is formed in the engine block  12 , preferably at a rearward end of the interbank valley  60 , through the bottom portion  66 , such that any oil collected in the interbank valley  60  can be evacuated therefrom. The first and second trough portions  74 ,  76  are each geometrically configured, e.g., via the peripheral trough wall  73 ,  78  and inclined surface  75 ,  79 , to direct fluid away from the recessed stratum  46  towards the fluid drainage port  90 . The first and second trough portions  74 ,  76  are also configured to allow for gravitational evacuation of fluid therefrom. For example, the first and second trough portions  74 ,  76  extend downward from the base portion  44  of the unitary body  40  such that of the first and second drains holes  92 ,  94  are positioned as the vertically lowest portion of the unitary body  42  relative to the interbank valley  60 . 
     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.