Abstract:
Passageways are provided within the combustion chamber of a fuel injected internal combustion engine to convey injected fuel to desired positions within the combustion chamber. The fuel-conveying passageways may be either open-sided or closed, and are positioned within the combustion chamber in substantial alignment with a respective spray jet of fuel, enabling optimum distribution of the fuel through the combustion chamber for enhanced mixing with air prior to combustion.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    This invention relates generally to fuel injected internal combustion engines and more particularly to structures within the combustion chamber of such engines through which fuel injected is transported to respective desired locations within the combustion chamber. 
         [0003]    2. Background Art 
         [0004]    Widespread concern for protection of the environment has led to increasingly stringent limitations on harmful emissions from internal combustion engines. Carefully timed and precisely metered injection of fuel directly into the combustion chambers of internal combustion engines has proven to be one method of reducing undesirable combustion product emissions. Traditional efforts have been directed to improving the mixing of fuel and air within the combustion chamber prior to combustion. For example, various shapes, such as wedge, hemispherical, elliptical, or toroidal, depressions in the piston crown, and pre-chamber, scroll, and other cylinder structures have been proposed to increase the homogeneity and dispersion of the fuel/air mixtures within the combustion chamber prior to combustion. 
         [0005]    Heretofore, fuel/air mixing improvements have been directed to increased mixing and flow control of the mixture. For example, U.S. Pat. No. 2,269,084 granted on Jan. 6, 1942 to J. J. McCarthy for an Internal Combustion Engine describes the use of arcuate ribs and baffles on the piston crown that cooperate to direct intake air drawn into the combustion chamber during the intake stroke into a vortex that is formed into a rapidly whirling air column that achieves its greatest turbulence just before fuel is injected into the combustion chamber. In a similar manner, U.S. Pat. No. 4,617,888 granted Oct. 21, 1986 to John C. Dent for a Piston for Internal Combustion Engines, proposes the use of arcuate ribs extending above the piston crown to provide turbulence in the fuel/air mixture prior to combustion and prevent the combustion flame front from spreading straight across the top of the piston without being deflected by one of the ribs. More recently, U.S. Patent Publication No. US2007/0044755A1 published Mar. 1, 2007 for a Device and Method to Increase Fuel Burn Efficiency in Internal Combustion Engines by Harry V. Lehmann proposes the use of vanes extending outwardly from the top of the piston to induce vortexes in the fuel/air mixture prior to combustion. 
         [0006]    Notwithstanding all previous attempts to improve combustion fuel/air mixing, further improvements are needed to achieve lower engine emissions and better fuel economy. None of the aforementioned proposals are directed to better placement and distribution of the injected fuel within the combustion chamber prior to mixing with the intake air charge. The present invention is directed to overcoming the problem of less than ideal distribution of fuel in the combustion chamber prior to mixing with air and subsequent combustion. In accordance with the present invention, improved placement and distribution of fuel within the combustion chamber is achieved by transporting portions of the fuel, after discharge from a fuel injector, to optimally preferred areas of the combustion chamber before being introduced into, and mixed with, intake air. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with one aspect of the present invention, a combustion chamber for fuel injected internal combustion engine has at least one flume positioned within the combustion chamber. The word “flume,” as used herein, means a structure that provides a channel or conduit for conveying, or transporting, fuel after discharge from a fuel injector to a desired location within the combustion chamber. More specifically, in accordance with the present invention a flume has at least one passageway extending through the flume in substantial alignment with a predefined direction of flow of the injected fuel. At least a portion of the injected fuel is conveyed through the passageway and subsequently conducted to a predetermined portion of the combustion chamber. 
         [0008]    Other features of the combustion chamber embodying the present invention include a nozzle of the fuel injector having a plurality of ports through which the fuel is injected into the combustion chamber in separately directed spray jets, and the combustion chamber having a plurality of flumes each of which is aligned with a respective one of the spray jets. 
         [0009]    Still another feature of the combustion chamber embodying the present invention includes the fuel injector being centrally located within the combustion chamber, with each of the spray jets of fuel discharged from the injector nozzle being directed in a respective separate radial direction from the nozzle, and the plurality of flumes are disposed circumferentially around the combustion chamber in radially spaced relationship from the nozzle. 
         [0010]    Yet another feature of the combustion chamber embodying the present invention includes the flumes being disposed on the crown of the piston. 
         [0011]    In yet another embodiment of the combustion chamber embodying the present invention, the flumes are positioned on the cylinder head. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A more complete understanding of the combustion chamber or fuel injected internal combustion engine can be had by reference to the following detailed description when taken in conjunction with the accompanying drawings, wherein: 
           [0013]      FIG. 1  is a plan view of a piston embodying the present invention, having a plurality of fuel-directing flumes circumferentially arranged around the periphery of the piston; 
           [0014]      FIG. 2 . is a cross-sectional view of the piston and associated combustion chamber embodying the present invention, taken along the line of  2 - 2  of  FIG. 1 ; 
           [0015]      FIG. 3  is a cross-sectional view of the piston and associated combustion chamber embodying the present invention, taken along the line  3 - 3  of  FIG. 1 ; 
           [0016]      FIG. 4  is a plan view of a piston having a plurality of fuel-directing fumes circumferentially arranged in the combustion chamber in close proximity to the fuel injector, in accordance with the present invention; 
           [0017]      FIG. 5  is a cross-sectional view of the piston and associated combustion chamber embodying the present invention, taken along the line  5 - 5  of  FIG. 4 ; 
           [0018]      FIG. 6  is a cross-sectional view of another embodiment of the present invention in which the fuel-directing flumes are positioned on a cylinder head surface in the combustion chamber. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    A preferred embodiment of a combustion chamber, generally indicated by the reference numeral  10 , for a fuel injected internal combustion engine is illustrated in  FIGS. 1-3 . The combustion chamber  10  is defined by a cylindrical circumferential wall, or bore,  12 , a cylinder head  14 , and the crown  16  of a piston  18 . The piston  18  is reciprocatably moveable, i.e., capable of alternating up and down or back and forth movement, within the bore  12 . The combustion chamber also has one or more intake and exhaust valves, not shown for the sake of better illustrating the salient features of the present invention. 
         [0020]    In this embodiment of the present invention, a fuel injector  20  is mounted in the cylinder head  14  and has a nozzle  22  extending into the combustion chamber  10 . The nozzle  22  is centrally located within the combustion chamber  10  and has a plurality of holes, or ports, through which fuel is injected into the combustion chamber in separately directed spray jets  24 . As illustrated in this embodiment, the nozzle  22  has 8 ports through which fuel is injected into the combustion chamber in 8 discrete conically-shaped spray jets  24 , each having a predefined included angle δ, in separate predefined radial directions. Accordingly, the combustion chamber  10  has a plurality of flumes, each generally indicated by the reference numeral  26 , circumferentially spaced around the periphery of the combustion chamber. Each of the flumes  26  is in alignment with a respective one of the spray jets  24 . 
         [0021]    In this embodiment, each of the flumes  26  is a structure comprising of plurality of radially spaced apart barrier walls  28 ,  30 ,  32 ,  34 , each having a respective passageway  36 ,  38 ,  40 ,  42  in coaxial alignment with a respective one of the spray jets  24 . The passageways  36 ,  38 ,  40 ,  42  have progressively decreasing cross-sectional areas so that the spray jet  24  is divided into roughly equal proportions as it passes through the flume structure  26  and the momentum of the fuel is desirably maintained throughout passage through the flume. The fifth barrier wall  44  is positioned at the radially outer end of the flume  26  and provides a solid barrier prohibiting further radial conveyance of the fuel contained in the spray jet  24 . The barrier walls  28 ,  30 ,  32 ,  34  of each flume  26  are disposed in respective recesses  46  provided in the periphery of the crown  16  of the piston  18 . 
         [0022]    In operation, each of the separately defined conically expanding fuel spray jets  24  discharged from the nozzle  32  of the fuel injector  20  impinge on a respectively aligned one of the flumes  26 . The outer boundary of the circular cross-sectional area of the fuel spray jet  24  impinging on the first barrier wall  28  of the flume  26  is indicated by dash lines  48  in  FIG. 3 . 
         [0023]    The flume structure  26  separates a fuel spray jet  24  into substantially equal portions and directs the separated portions upwardly and circumferentially into the peripheral area of the combustion chamber  10 . For example, as illustrated in this first embodiment, the flume  26  has 5 barrier walls  28 ,  30 ,  32 ,  34  and  44  with coaxially aligned passageways  36 ,  38 ,  40  and  42  respectively provided through the first 4 barrier walls through which portions of the spray jet  24  are conveyed. In the course of passing through the aligned passageways  36 ,  38 ,  40  and  42  the fuel spray jet  24  is divided into five substantially equal portions each comprising about twenty percent of the total fuel discharged in the discrete spray jet  24 . Thus, the passageway  36  through the first barrier wall  28  has a cross-sectional area that allows about four-fifths, or eighty percent, of the fuel directed to the first barrier wall to pass through to the second barrier wall  30 . The remaining one-fifth, or twenty percent, of the spray jet  24  not passing through the passageway  36  in the first barrier wall  28  is deflected upwardly and laterally outwardly into the combustion chamber  10 . Similarly, three-fourths, or seventy-five percent, of the fuel that passes the first barrier wall  28  is passed through the passageway  38  in the second barrier wall  30 . The one-fourth, or twenty-five percent, presenting twenty percent of the total initial fuel contained in the spray jet  24 , not passed through the passageway  38  is deflected upwardly and circumferentially outwardly through the channel formed between the first barrier wall  28  and the second barrier wall  30  and into the periphery of the combustion chamber  10  whereat it is then advantageously mixed with intake air prior to combustion. 
         [0024]    In a similar manner, two-thirds, or about sixty-seven percent, of the fuel spray jet  24  that passes through the second barrier wall  30  is passed through the passageway  40  in the third barrier wall  32 . The remaining one-third, or about thirty-three percent, again comprising twenty percent of the initial fuel jet spray  24 , not passed through the passageway  40  is deflected upwardly and circumferentially outwardly into the periphery of the combustion chamber  10  and subsequently mixed with air prior to combustion. 
         [0025]    Continuing in the same manner, one-half, or fifty percent, of the fuel conducted through the passageway  40  in the third barrier wall  32  is passed through the passageway  42  in the fourth barrier wall  34 . The remaining one-half, or fifty percent, again comprising twenty percent of the initial fuel jet spray  26  is deflected through the channel formed between the third and fourth barrier walls  32  and  34  and thence upwardly and circumferentially outwardly into the periphery of the combustion chamber  10 . 
         [0026]    The fuel passing through the passage way  42  represents the remaining twenty percent of the initial fuel carried in the spray jet  24 . The remaining twenty percent portion of the fuel spray jet  24  impinges on the fifth barrier wall  44  and is deflected through the channel formed between the fourth barrier wall  34  and the fifth barrier wall and is directed upwardly and circumferentially outwardly into the periphery of the combustion chamber  10  and mixed with intake air prior to combustion. 
         [0027]    The above-described preferred embodiment of the present invention is presented for illustrative purposes. For example, each of the flume structures may consist of more or fewer than five barrier walls and the passageways through the barrier walls may not all be sized to equally divide the spray jet. Also, the passageways may have a differently shaped cross section, such as rectangular, instead of the circular shapes shown. Furthermore, the flume may be positioned at other positions within the combustion chamber and have a different structure, such as the flume described in the following embodiments. 
         [0028]    In a first alternative embodiment, a flume structure  52  is illustrated in  FIGS. 4 and 5 . In this example, the flume  52  is positioned on the crown  16  of a piston  50  in close radial proximity to a fuel injector  54  having a four-hole nozzle  56  through which fuel is injected into the combustion chamber, generally indicated by the reference numeral  58 . Through this arrangement, fuel is injected into the combustion chamber  58  in four conically-shaped discrete spray jets  60 . Each directed in a separate, predefined radial direction and having a predefined included angle δ. 
         [0029]    In this first alternative embodiment, the flumes  52  are unitary structures having a plurality of slots, or rectangular passageways,  62  extending through each structure. Each of the passageways  62  have an entrance port  64 , a rear exist port  66  and two side exit ports  68 . Each of the flumes  52  are aligned with a respective fuel spray jet  60 . The passageways  62  are positioned to be in substantial alignment with a respective one of the fuel spray jets  60  when the piston is at a desired predetermined position, e.g., within about ten degrees TDC, so that at least a portion of the fuel in the spray jet is transported through the passageway  62  and subsequently conducted to a predetermined position within the combustion chamber  58 . 
         [0030]    More specifically, the passageways  62  are preferably tapered front to back as best shown in  FIG. 5 , i.e., the entrance ports  64  of the passageways  62  have a larger cross-sectional area than that of the rear exit ports  66 . It is desirable that the collective total cross-sectional areal of the rear and side exit ports  66  and  68  not be less than the cross-sectional area of an associated entrance port so that fuel momentum is maintained during flow through the flume  52 . Desirably, the rear and side exit ports  66  and  68  have a small chamfer at the respective port opening to increase the dispersion angle the fuel exiting the ports. 
         [0031]    In a second alternate embodiment illustrated in  FIG. 6 , a combustion chamber  70  has the flume  52 , described in the previous embodiment, mounted on the cylinder head  72 . This arrangement, enables fuel to be injected into the combustion chamber over a wider range of piston positions and injection timing, because the position of the piston  74  is not as critical as it is in the earlier described embodiments. 
         [0032]    It should be understood that the flumes may have different structures and locations than those shown, the principal requirement being that the flume convey fuel injected into the combustion chamber to a desired position within the chamber for optimal mixing with air prior to combustion. To that end, the flume must provide passageways through which fuel is conveyed to the desired location within the combustion chamber. 
         [0033]    The above-described flume designs are intended to maximize the interaction between the piston bowl/combustion chamber configuration and the diesel fuel/gaseous fuel jets to achieve low emissions and particulate matter formation. Passageways provided within each of the flume structures convey fuel to desired portions of the combustion chamber to enhance the mixing of fuel and air. The passageway take advantage of the fuel jets high momentum by separating and redirecting discrete fuel jet into preferred portions of the combustion chamber so that better fuel and air mixing can be achieved. A series of channels may be stacked in the radial direction, as described in the preferred illustrative embodiment, to provide maximum dispersion on top of the piston squish/quench zone. Alternatively, similar channels may be oriented to improve dispersion in the circumferential and radial direction as well. The first and second alternative embodiments of the present invention, describe a flume structure that provides an impingement target containing channels through which separated portions of a fuel spray jet are conveyed to desired locations within the combustion chamber. To that end, the impingement targets and associated passageways may be positioned on either the piston or the cylinder head, depending on a preferred application. 
         [0034]    Thus, although the present invention is described in terms of preferred exemplary embodiments, those skilled in the art will recognize that the construction and position of the flumes may be modified as discussed above. Such arraignments of flumes embodying the present invention are intended to fall within the scope of the following claims. 
         [0035]    Other aspect, features, and advantages of the present invention may be obtained from a study of this disclosure and the drawings, along with the appended claims.