Abstract:
Method and apparatus useful in simultaneously enhancing the fuel consumption efficiency of an ICE, with concomitant enhancement of the power delivered by the engine, and reduction of undesirable exhaust emissions. One embodiment of the method of this invention includes the steps of introducing a fuel/air mixture to the main combustion chamber of the ICE, providing a flame front pre-combustion system which enhances the timely delivery of multiple flame fronts to specific locations within the main combustion chamber for substantial spontaneity of ignition and combustion of the fuel/air mixture disposed within the combustion chamber when the crankshaft is within about 5 degrees nearer top dead center (TDC) than the timing established by a standard operation map for the ICE in question and which employs a conventional spark plug disposed within the combustion chamber. Such combustion continues over that time period during which the crankshaft travels at least past TDC and into its power stroke.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part application of co-pending U.S. patent application Ser. No. 11/689,852, filed Mar. 22, 2007, entitled: Ignition System for Internal Combustion Engine, which is a continuation-in-part of co-pending U.S. patent application Ser. No. 11/622,801, filed Jan. 12, 2007, entitled: Spark Ignition Modifier Module And Method, the whole of each of which is incorporated herein by reference and upon which priority is claimed. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       FIELD OF INVENTION 
       [0003]    This invention relates to internal combustion engines, such as are commonly used for propelling motor vehicles. 
       BACKGROUND OF INVENTION 
       [0004]    Internal combustion engines (ICE), in particular the well-known Otto-cycle or “four stroke” engine) are fueled with a combustible mixture of fuel (e.g. gasoline) and air. Perhaps two of the most undesirable characteristics of an ICE are the relatively low efficiency and relatively high contaminant emission exhibited by these engines. This inefficient utilization of the fuel, detracts from control of engine power output, and undesirable, and even harmful emissions. 
         [0005]    For purposes of the present disclosure, the four strokes of the engine comprise an intake stroke, a compression stroke, a power stroke and an exhaust stroke. The cycle begins when the piston of the engine is at top dead center (TDC). Herein, the four stroke cycle is deemed to commence when the rotational position of the crankshaft (which moves with the piston through its strokes) is such that the piston is at TDC. All references to rotational positions of the piston are based upon the degrees of rotation of the crankshaft from the starting TDC of the piston. For example, 10 degrees before TDC refers to the rotational position of the crankshaft being 10 degrees before the commencement of a power stroke of the engine cycle. 
         [0006]    Probably, the most common of the many attempts of prior art devices and methods for attacking the problems associated with ICEs is utilization of a flame front initiated outside the normal combustion chamber of an ICE and thereafter propagated into the main combustion chamber wherein such flame front ignites the usual charge of fuel/air mixture(herein at times F/A or F/A mixture) disposed within the combustion chamber. Whereas some of these attempts have achieved at least limited desired results, none of such attempts are known to have economically or otherwise effectively provided both the sought after increase in efficiency and simultaneous reduction of environmentally unfriendly exhaust emissions associated with ICEs. 
         [0007]    Currently, in the ICE industry, there are two aspects of the industry which in part tend to require different possible means for enhancement of the efficiency of the ICE plus minimization of the exhaust emissions from the engine. The first such aspect relates to the number of ICEs currently in use and which employ carburetor systems and the second aspect relates to the more recent and currently expanding market for ICEs employing engine control modules (ECM) (which control spark timing, fuel injection, etc). 
         [0008]    In the prior art the concept of employing flame front(s) initiated externally of the main combustion chamber and propagated into the main combustion chamber, for ignition of the fuel/air mixture within the main combustion chamber has been somewhat heavily pursued. This concept is more or less compatible with either carburetor or fuel injection systems, but its uses are expanding primarily into those engines employing fuel injection for introduction of a quantity of a fuel/air mixture into the engine combustion chamber once per cycle of the engine through its intake stroke, compression stroke, power stroke and exhaust stroke of the piston. 
         [0009]    In those ICEs which employ a carburetor for the introduction of an F/A mixture into the combustion chamber of the engine, the F/A mixture disposed within the combustion chamber is ignited by means of a spark plug which projects into the combustion chamber. It has been proposed in the prior art to employ a relatively lean F/A mixture as an aid toward reduction of undesirable emission products. Heretofore, mere incorporation of a flame front pre-combustion system in a carburetored ICE has failed to be economically, operationally or otherwise suitably beneficial. 
         [0010]    ICEs which are controlled by an ECM, for example, commonly utilize stoichiometric F/A mixtures for enhanced utilization of the fuel employed to operate the engine. These EMC controlled systems tend to generate excessive nitrogen-containing emission products. The well-known “three-way catalyst” system has been found effective to preclude such nitrogen-containing emission products from entering the atmosphere, however, this catalyst system is ineffective in combination with carburetored ICEs. 
         [0011]    Fuel/air mixture is one of the more important principles of internal combustion engine operation. For gasoline, the stoichiometric fuel/air ratio is 14.7:1. That is, 1 unit of fuel mass is consumed for every 14.7 units of air mass that are drawn into the engine. The stoichiometric is neither most fuel efficient nor delivers the most power, it is a compromise. 
         [0012]    The stoichiometric ratio usually is the least polluting, because the catalytic converter can most easily remove pollutants at such a ratio. The stoichmetric mode is most often used during cruising and light acceleration. 
         [0013]    For optimum power, a 12.7:1 (slightly fuel-rich) fuel/air ratio should be used. However, it is not very fuel efficient, it can foul spark plugs, and is polluting (the catalytic converter is outside its optimum range, and very polluting unburned hydrocarbons are released). Modern cars usually only use this mode (called fuel enrichment mode) under hard acceleration. 
         [0014]    For maximum fuel economy, a 16.1 (fuel-lean) fuel/air ration should be used. However, the lack of extra fuel to cool the engine results in hot, less dense intake air, reducing power. Also, the extra heat puts stress on engine parts, and increases octane requirement. Although less polluting than fuel-rich, fuel-lean produces large amounts of nitrogen oxides, as well as putting the catalytic converter out of its range. Lean mixtures are generally not used on modern, pollution-controlled vehicles. 
         [0015]    These factors have led to the practice of developing an Electronic Control Module for internal combustion engines wherein various operational factors of the engine are monitored and employed to provide to the IEC the most fuel efficient, minimum contaminating and otherwise desirable fuel/air ratio which provides the maximum torque at any one of a range of engine rpms which are representative of the anticipated operating conditions of the engine (e.g. low rpms at idle speeds to high rpms at higher or more torque-demanding operating conditions.) This concept “torque control” has led to the use of operation maps developed for a given engine. Such maps take into consideration the timing of the initiation of the spark ignition of the fuel/air mixture disposed within the combustion chamber of the engine (before TDC of the crankshaft) as will maximize the torque developed at any given combination of fuel/air intake at any given rpm of the engine. That is, these maps are based upon torque output values. Inasmuch as the torque values desired at different rpms of the engine, the timing of the ignition of the combustion of the fuel/air mixture varies considerably between idle speeds and higher rpm speeds. Such maps are developed for a given engine employing a very large number of test runs of the engine at each combination of rpms and air flow into the combustion chamber of the engine. These maps, therefore, are specific for a given engine. Most commonly the operational map for a given engine is available from the manufacturer of the engine. However, one skilled in the art can develop an operational map for a given engine by following the multiple testing procedure referred to above. These operational maps have generally become the “standard” for ICEs, particularly where the ICE is controlled by an ECM. 
         [0016]    The present inventor has found, however, that enhancement of the efficiency of multiple aspects of the operation of an ICE, whether controlled by an ECM or a carburetor, can be materially enhanced. In accordance with the present invention, such enhancement is accomplished through the use of a flame front type pre-combustion system which effects commencement of the ignition of the fuel/air mixture disposed within the combustion chamber of an ICE at a time which is about 5 degrees later than the ignition time dictated by a prior art operational map. This retardation of the timing of ignition of the fuel/air mixture has been found possible over substantially all anticipated combinations of engine speed and rate of air flow into the combustion chamber of the engine. In certain combinations of engine speed and the lower air flow rates, the retardation of the timing may exceed 5 degrees, thereby further enhancing the efficiency of operation of the engine at such lower speed and air flow rate combinations. 
       SUMMARY OF INVENTION 
       [0017]    In accordance with one aspect of the present invention, the inventor has discovered a method and apparatus useful in simultaneously enhancing the fuel consumption efficiency of an ICE, with concomitant enhancement of the power delivered by the engine and acceptable exhaust emissions. One embodiment of the method of this invention includes the steps of introducing a fuel/air mixture to the main combustion chamber of an ICE, providing a flame front pre-combustion system disposed externally of the combustion chamber and which enhances the timely delivery of multiple flame fronts to specific locations within the main combustion chamber for substantial spontaneity of ignition and combustion of different portions of the fuel/air mixture disposed within the combustion chamber when the crankshaft is within about 5 degrees nearer top dead center (TDC) than the timing established by a standard operation map for the ICE in question and which employs a conventional spark plug disposed within the combustion chamber of the ICE. Such combustion continues over that time period during which the piston associated with the crankshaft travels from about 5 degrees before TDC, past TDC and at least partly through the engine power stroke. In the present invention, the propagation of the ignited F/A mixture within the combustion chamber maximizes the rate of buildup of heat and pressure within the combustion chamber at a time when the rotational position of the crankshaft, hence the position of the piston within the engine cylinder, is substantially at TDC, thereby maximizing the timing of the application of energy to the piston, thence to the crankshaft, with concomitant advantages. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES  
         [0018]      FIG. 1  is a schematic representation of one embodiment of apparatus embodying various of the features of the present invention; 
           [0019]      FIG. 2  is a schematic representation of a further embodiment of apparatus embodying various of the features of the present invention; 
           [0020]      FIG. 3  is a schematic representation of one embodiment of the introduction of multiple flame fronts into a combustion chamber of an internal combustion engine employing the present invention; 
           [0021]      FIG. 4  is a side elevation view of one embodiment of a flame cone useful in the present invention; 
           [0022]      FIG. 5  is a top end view of the flame cone depicted in  FIG. 4 ; 
           [0023]      FIG. 6  is a side elevation view, in section of the flame cone depicted in  FIG. 4 ; 
           [0024]      FIG. 7  is a further side elevation view, section, of the flame cone depicted in  FIG. 4 ; 
           [0025]      FIG. 8  is still further side elevation view, in section, of the flame cone depicted in  FIG. 4 ; 
           [0026]      FIG. 9  is a still further side elevation view, in section, of the flame cone depicted in  FIG. 4 ; 
           [0027]      FIG. 10  is a schematic representation of a further embodiment of apparatus useful in the present invention without employing a flame cone; 
           [0028]      FIG. 11  is a schematic representation of a portion of a conventional ICE; 
           [0029]      FIG. 12  is an operation map of a typical ICE (without a flame front pre-combustion system) supplied by the manufacturer of the ICE; 
           [0030]      FIG. 13  is an operation map of the ICE of  FIG. 12 , and including a flame front system of the present invention; and, 
           [0031]      FIG. 14  is a tabular representation of the differences in timing of commencement of combustion between the operation maps of  FIGS. 12 and 13 . 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0032]    The present invention relates to an ICE. Referring to  FIGS. 1 and 12 , a conventional ICE  10  includes a piston  12  reciprocatably mounted within a cylinder  14 . A connecting rod connects the piston with a crankshaft whose rotation transfers power to the drive train of a motor vehicle. Referring to  FIG. 1 , the cylinder opens into a combustion chamber  20  within which a fuel/air mixture (at times “F/A”) is ignited by a spark plug  44  and burned to develop pressure and heat effective to drive the piston within its cylinder, hence effect rotation of the crankshaft. Within the combustion chamber there is included an intake valve  22  through which “fresh” F/A is admitted to the combustion chamber and an exhaust valve  24  through which unburned (if any) F/A and emission products from the combustion of the F/A are dispelled from the combustion chamber. 
         [0033]    One embodiment of apparatus for carrying out the method of the present invention with an ICE is depicted in  FIG. 1 . In the depicted embodiment, there is provided a pre-combustion system  26  including a pre-combustion chamber  28  disposed externally of the main combustion chamber  20  of the engine (hereinafter the “combustion chamber”). This system further includes a generally hollow tubular flame cone  30  which is removably insertable into a first threaded portion  32  of a throughbore  34  which extends through the wall  36  of the head  38  of the internal combustion engine and terminates within the combustion chamber. In this embodiment, the flame cone occupies that portion  32  of the throughbore which is nearest the combustion chamber. That end  40  of the flame cone which is most external of the combustion chamber (yet within the throughbore) threadably receives therein the electrode end  42  of a common spark plug  44 . The combination of the electrode end of the spark plug and a portion  46  of the inner wall of the flame cone define the pre-combustion chamber  28  at a location about midway between the opposite ends of the throughbore, but in any event, fully within the throughbore. 
         [0034]    Further, in the depicted embodiment, the flame cone is provided with a central first channel  48  which provides for fluid communication between the pre-combustion chamber and the combustion chamber. Proximate the inboard terminal end  50  of the flame cone, there is provided a plurality of, commonly at least one, lateral channel  52  which extends generally laterally from the central channel at a location about the outer periphery of the central channel and which is spaced apart from the central channel. This lateral channel functions to divide a portion of a flame front moving through the central channel into a laterally directed flame front entering the combustion chamber at a spaced apart location relative to the location of entry of the flame front exiting the central channel and entering the combustion chamber. 
         [0035]    In this embodiment, (see  FIGS. 1 and 2 ) the inboard terminal end of the flame cone extends into the combustion chamber to the limited extent that the exit end of the central channel and the exit port  56  of the at least one lateral channel  52  may directionally introduce respective flame fronts  58 ,  60  into the combustion chamber without material interference with the propagation of the flame fronts by the structure of the combustion chamber or other element disposed within the combustion chamber. Each of these flame fronts constitutes a source of ignition for preselected portions of a fuel/air mixture disposed at different locations within the combustion chamber. 
         [0036]    In a preferred embodiment, the central channel extends in direct, substantially unimpeded fluid flow communication between the pre-combustion chamber and the inboard terminal end of the flame cone. The depicted central channel preferably is of a hollow cylindrical geometry which preferably is substantially straight. 
         [0037]    Further, as depicted in  FIGS. 1 and 2 , the outboard end of the throughbore through the wall of the engine head is enlarged to receive therein a first body portion  62  of the flame cone. This enlargement of the throughbore and the outer wall  64  of the outboard end of the first body portion of the flame cone are spaced apart to define an annular void space  70  therebetween. This annular space is selected to permit the receipt therewithin of a tool for grasping and rotationally screwing the flame cone into the throughbore. 
         [0038]    Referring to  FIG. 2 , a stop in the form of an external circumferential slanted shoulder in the wall of the throughbore is provided for limiting location of the flame cone in the throughbore. The extent of insertion of the spark plug into the first body portion of the flame cone is similarly limited by means of a circumferential shoulder  74  defined internally of the flame cone. These stops may further serve to seal off selected interior areas of the apparatus from the environment external of the ICE. 
         [0039]    As noted, the pre-combustion chamber is fully disposed within the throughbore through the head wall, and preferably approximately midway between the opposite ends of the throughbore through the engine head wall. The present inventor has found that, as so positioned, the pre-combustion chamber and a substantial portion of the central channel thereof, are sufficiently proximate to the existing cooling channel or channels  76  of the ICE as to provide cooling of the pre-combustion chamber and/or other portions of the flame cone and thereby preclude inordinate buildup of heat and possible inadvertent pre-ignition of any fuel/air mixture entering or resident within the pre-combustion chamber and/or the central channel. 
         [0040]    The apparatus of the present invention is incorporated into the throughbore of an ICE from a position external of the combustion chamber of the ICE. No removal of the head of the ICE is required. After the present apparatus is in place, start up of the ICE and movement of the piston through its compression stroke, feeds fuel/air mixture primarily through the central channel into the pre-combustion chamber. Upon firing of the spark plug, ignition of the fuel/air mixture within the pre-combustion chamber is initiated, thereupon, a flame front which is of substantial size, promptly develops and propagates along the central channel. Referring to  FIG. 3 , proximate the inboard terminal end of the central channel, this flame front is divided into at least first and second, and preferentially third flame fronts  58 ,  60  and  61 , respectively. A first portion  58  of the flame front exits the larger diameter central channel, hence is directed toward the intake valve where “fresh” fuel/air mixture is most likely to accumulate. A second portion of the flame front moving through the central channel exits through the at least one lateral channel. In the depicted embodiment, the first flame front exiting the central channel is of a greater size, but of a lesser velocity, than the size and velocity of the second flame front which exits the terminal end of the central channel via the at least one lateral channel. This central channel is directionally aligned with the location of the intake valve disposed within the combustion chamber. Upon the flame front from the central channel reaching the fresh fuel/air mixture in the vicinity of the intake valve, such mixture is thereupon rapidly ignited, creating a relatively large flame front which rapidly spreads within the combustion chamber, building up pressure and heat. 
         [0041]    In this depicted embodiment, the at least one lateral channel which also exits the inboard terminal end of the flame cone into the combustion chamber, is directionally aligned with the location of the exhaust valve in the combustion chamber. As depicted in  FIG. 3 , the internal diameter of this at least one lateral channel is less than the internal diameter of the central channel, hence the flame front exiting this lateral channel exhibits a size less than the size of the flame front exiting the central channel, and a velocity which is greater than the velocity of the flame front exiting the central channel. 
         [0042]    The inventors have found that, by reason of the proximity of the inboard terminal end of the central channel to the intake valve and the larger internal diameter of the central channel, relative to the radially lateral channel, a quantity of the incoming “fresh” fuel/air mixture within the combustion chamber during the compression stroke of the engine is preferentially conveyed from the combustion chamber into the pre-combustion chamber via the central channel. By this means, the quantity of fuel/air mixture drawn into the pre-combustion chamber in the course of the compression stroke of the engine includes relatively little, if any, residual unburned gas(es) from a preceding cycle of the engine which may not have been exhausted during such preceding engine cycle. 
         [0043]    The second flame front  60  exiting the central channel simultaneously exits via the exit port  56  of the lateral channel which is directionally aligned with the exhaust valve in the combustion chamber. In an ICE, the hottest location within the combustion chamber aside from the spark plug electrode is proximate the exhaust valve. This factor is important in that the flame front developed proximate the intake valve by the present invention rapidly spreads within the combustion chamber including toward the exhaust valve. This fast combustion of the fuel/air mixture within the combustion chamber quickly develops large pressures and large quantities of heat which tend to promote detonation of the fuel/air mixture proximate the hot exhaust valve. Such rapid buildup of pressure and heat is desirable in that they enhance conversion of the combustion process to energy useful for driving the piston through its power stroke, ie. conversion of the energy associated with the high pressure and heat into work (driving the piston). It will be recognized that the buildup of pressure and heat and the concomitant energy associated with the pressure and heat, within the combustion chamber is anti-productive if such buildup takes place before the piston has passed TDC. Specifically, if the energy available due to the high pressure and heat buildup within the combustion chamber is imparted to the piston before the piston reaches TDC, such energy applied to the piston is transferred to the bearings which connect the piston rod to the crank shaft and resultant buildup of friction within such bearing (and potentially other elements of the drive train of the vehicle). Aside from the damage associated with such friction, the value of the energy is lost, commonly as heat to the radiator or other component of the vehicle. This loss of energy can materially reduce the overall efficiency of the combustion of the fuel/air mixture within the combustion chamber of the engine. 
         [0044]    Additionally, as noted above, it has been found that the rapid propagation of the flame front emanating from the area of the intake valve and the concomitant buildup of pressure and heat near the exhaust valve tends to promote detonation at the hot exhaust valve. In accordance with one embodiment of the present invention, such detonation is avoided by forming the lateral channel which exits the inboard end of the central channel, of a smaller internal diameter than the internal diameter of the central channel and directing such flame front emanating from the lateral channel toward the exhaust valve of the ICE. The lateral channel, being of smaller internal diameter than the internal diameter of the central channel, projects a relatively fast forward moving flame front toward the exhaust valve, thereby ensuring that such flame front reaches the vicinity of the exhaust valve and initiates combustion of that fuel/air mixture disposed proximate the exhaust valve before the buildup of pressure and heat from the overall combustion of fuel/air mixture within the combustion chamber delivers its associated high pressure and heat to the vicinity of the exhaust valve and before molecular structure has time to cause detonation. This timing of arrival of the flame front issuing from the lateral channel of the flame core precedes or substantially coincides with the arrival of that flame front propagating outwardly from the vicinity of the intake valve. The forward propagation of the second flame front thus reaches and initiates combustion of the fuel air mixture proximate the exhaust valve before such fuel/air mixture can be detonated by the hot exhaust valve. 
         [0045]    In addition to the elimination of “knocking” due to detonation of the fuel/air mixture in the vicinity of the exhaust valve, the “timed” delivery of separate flame fronts to selected regions within the combustion chamber aids in maximizing the conversion of the pressure and heat within the combustion chamber into work, namely, driving of the piston of the engine into and through its power stroke. 
         [0046]    Timing (degrees before TDC of initiation of combustion within the combustion chamber of the engine) of the ignition of the F/A mixture within the combustion chamber of an ICE is related to the quantity of F/A mixture entering the engine over the entire spectrum of anticipated engine rotations per minute (rpm). An operational map of a given ICE is available from the manufacturer of the engine.  FIG. 12  shows an operational map for a GM 5.3 liter engine, as an example of a “standard” (factory supplied ignition control system) (no flame front) engine controlled by an ECM. From  FIG. 12 , it will be seen that ignition of the F/A mixture within the combustion chamber of the engine is commenced at 18 degrees before TDC when the engine is idling at 400 rpm and with an infeed of 0.08 grams per cylinder of air flow into the combustion chamber. When the air flow into this same idling engine is increased to 0.64 grams per cylinder, the EOM commences the ignition of the F/A mixture at 8.5 degrees before TDC. 
         [0047]      FIG. 13  shows the relationship of engine speed and air flow into the combustion chamber of the same engine equipped with a flame front pre-combustion system of the present invention. In this figure, it will be noted that when the engine employing the present invention is operating at 400 rpm with an air flow of 0.08 gram per minute, the commencement of the ignition of the F/A mixture within the combustion chamber is commenced at 13.0 degrees before TDC. This retardation of the commencement of the ignition of the F/A mixture by 5 degrees closer to TDC by means of the present invention has been found to enhance the efficiency of utilization of the F/A mixture by as much as 7% over the efficiency of utilization of the F/A mixture when employing a “standard” engine. The table presented in  FIG. 14  depicts the ability of the present invention to retard the ignition of the F/A mixture within the combustion chamber by 5 or fewer degrees before TDC over about 300 of the 360 depicted possible combinations of grams per cylinder air flow for engine speeds ranging from idling to 4000 rpm. As noted, this factor provides for both enhanced efficiency of utilization of the F/A mixture at all engine speeds and an extended range of F/A infeeds to the combustion chamber of an ICE and concomitant elimination of most environmentally undesirable emissions (with the exception of nitrogen-bearing gasses which are readily extracted and rendered harmless by a conventional three-way catalyst). 
         [0048]    In accordance with another aspect of the present invention, enhancement of the conversion of pressure and heat within the combustion chamber to work, i.e. driving the piston of the engine into and through its power stroke, is enhanced by selection of the timing of the commencement and scheme of propagation of the flame fronts from the pre-combustion chamber into and within the combustion chamber. 
         [0049]    More specifically, in the preferred embodiment of the present invention, the activation of the spark plug for igniting the fuel/air mixture within the pre-combustion chamber is selected to occur approximately 5 degrees of crankshaft rotation later than the activation point used for standard spark plug systems wherein the electrode-bearing end of the spark plug is positioned internally of the combustion chamber. This retardation action moves the ignition commencement point approximately 5 degrees prior to TDC of the crankshaft (piston). This timing of the pre-combustion so near the TDC position of the crankshaft provides sufficient time for the spark plug to ignite the fuel/air mixture in the pre-combustion chamber, for the development of a flame front within the pre-combustion chamber, propagation of such flame front into and through the central channel and outwardly therefrom in divided individual flame fronts toward the intake valve and the exhaust valve before the crankshaft reaches TDC. The present invention thus provides concomitant optimum buildup of pressure and heat within the combustion chamber as near to, but not materially prior to, TDC as reasonably achievable without detonation. By this means, conversion of pressure and heat within the combustion chamber to energy for commencing movement of the piston of the engine into and through the engine power stroke is timed to retard material generation of pressure and heat buildup within the combustion chamber before the crankshaft rotation achieves TDC but with maximization of the rate of buildup of pressure and heat within the combustion chamber once the crankshaft has achieved TDC and the piston is ready to be driven into and through its power stroke. Such control over the propagation of the flame fronts toward the intake valve and the exhaust valve of the ICE maximizes the efficiency of operation of the ICE, i.e., maximization of combustion of the fuel/air mixture injected into the combustion chamber, hence enhanced correlation of the burning of the fuel/air mixture within the combustion chamber and the timely conversion of such burning action into energy for driving the ICE, as opposed to the conversion of pressure and heat within the combustion chamber to energy at a time prior to the piston reaching TCD. As noted, in the situation where the maximization of the pressure and heat (energy available for work) within the combustion chamber occurs at a time when the piston nears the completion of its compression stroke and is not yet positioned at TDC, the application of work against the piston is more than wasted. More specifically, such energy acts to counter the movement of the piston toward its TDC position between its compression and power strokes with concomitant friction between the piston rod and the crankshaft (and other components of the engine) and/or dissipation of the such energy to the cooling system of the engine and/or various components of the engine. 
         [0050]    In a preferred embodiment of the present invention, continued burn of the fuel/air mixture within the combustion chamber and the accompanying generation of energy within the combustion chamber provide energy needed to move the piston through its power stroke. In the present invention, this continued burn is in part contributed to by a further (second) lateral channel  53  leading from the central channel into the combustion chamber via an exit port  93 . This further lateral channel emits a flame front  61  thereform into the combustion chamber in a direction which is generally tangential to the inner circumferential wall of the combustion chamber. This flame front, being directed to those regions within the combustion chamber where fuel/air mixture may accumulate or reside along the outer borders of the flame fronts associated with the ignition occasioned by the flame fronts of the central channel and that lateral channel which is directed toward the exhaust valve, enhances maximization of the combustion of the fuel/air mixture entering the combustion chamber through the intake valve during a given cycle of the engine, including unburned fuel/air mixture which may be accumulated about the circumferential inner wall of the combustion chamber. This additional contribution to the overall burning of the fuel/air mixture within the combustion chamber adds to the overall total pressure and heat buildup within the combustion chamber during a given cycle of the engine, and especially enhancement of potential energy available for work in the form of movement of the piston through its power stroke. 
         [0051]    For example, in the embodiment depicted in  FIGS. 4-10 , the further (third) portion of the flame front  61  exits the central channel via a further lateral channel  53  which is directionally aligned along a path which does not intersect nor interfere with the propagation of the flame fronts aimed toward the intake and exhaust valves. Commonly, this third flame front may be directed generally along a tangent to the inner circumferential wall of the combustion chamber to reduce the wall impingement effect (where incoming fuel/air mixture is swept by centrifugal forces onto the circumferential inner wall of the combustion chamber) and/or to “sweep” fuel air mixture from such areas into the remainder of the combusting fuel/air mixture. It is not known for certain to what extent this “wall sweeping” action enhances the efficiency of combustion of the fuel/air mixture disposed within the combustion chamber, but experience has demonstrated that, as described herein, the combination of three exits ports from the central channel leading from the pre-combustion channel into the combustion chamber, may afford material enhancement of the efficiency of operation of the ICE by as much as 10% and a material reduction in many of the undesirable environmentally detrimental gases heretofore known to be produced in the exhaust emissions of ICEs. Whereas nitrogen-containing gases (NOx) have been observed in the exhaust emissions of ICEs equipped with the present invention, such gases are readily extracted from the exhaust emissions employing well known catalytic measures. 
         [0052]    Accordingly, one embodiment of the method of the present invention includes the steps of 
         [0053]    (a) providing a fuel/air mixture useful for combustion within the combustion chamber of an ICE which includes a cylinder, a piston reciprocatably mounted within said cylinder, and a crankshaft operatively associated with the piston, 
         [0054]    (b) externally of the combustion chamber, providing a pre-combustion chamber having a first channel of a first internal diameter in fluid flow communication between the pre-combustion chamber and the combustion chamber and aligned with the location of an intake valve within the combustion chamber, and at least one channel extending from the central channel into the combustion chamber and aligned with the location of an exhaust valve within the combustion chamber, 
         [0055]    (c) introducing a quantity of the fuel/air mixture into the combustion chamber, 
         [0056]    (d) transferring a quantity of fuel/air mixture from the combustion chamber into the pre-combustion chamber, 
         [0057]    (e) igniting the quantity of fuel/air mixture within the pre-combustion chamber to develop a flame front which propagates along the central channel toward the combustion chamber, 
         [0058]    (f) dividing the flame front within the central channel into at least two separate flame fronts, one of which exits the central channel and enters the combustion chamber in the direction of the intake valve in the combustion chamber, 
         [0059]    (g) directing another of the separate flame fronts from the central channel into the combustion chamber in the direction of the exhaust valve in the combustion chamber, and 
         [0060]    (h) timing the initiation of combustion of said quantity of fuel/air mixture within the pre-combustion chamber to commence when the crankshaft associated with the piston is operatively within about 5 degrees before TDC. 
         [0061]    In one embodiment of the present invention, as depicted in  FIG. 11 , there is defined (such as by casting, machining or other forming means) a throughbore  34  through the wall  36  of the head  38 , such throughbore extending from the outer wall  68  of the head to a terminal location proximate the combustion chamber  20  of the ICE. At this terminal location  98 , the inner wall of the head is provided with a plurality of exit ports  52 ,  53  and  54  including a plurality of lateral channels which extend generally radially from a central channel  48 , to provide for division and distribution of a flame front moving through the central channel toward the combustion chamber into a plurality of spaced apart flame fronts as described hereinabove. No flame cone is employed in this embodiment. 
         [0062]    In the embodiment depicted in  FIG. 11 , that end of the throughbore adjacent the outer wall of the head is internally threaded to receive therein the threaded end of a conventional spark plug  44 . The extent of insertion of the spark plug is limited by a circumferential shoulder  100  in the throughbore such that the electrode of the spark plug is disposed approximately midway between the inner and outer walls of the head and fully within the throughbore. At a location intermediate the inboard and outboard ends of the throughbore, the internal diameter of the throughbore is reduced, thereby defining a pre-combustion chamber  28  proximate the midpoint of the length dimension of the throughbore. Again, this positioning of the pre-combustion chamber is sufficiently proximate to the existing cooling channel  76  or channels of the ICE as to preclude inordinate buildup of heat and possible pre-ignition of any fuel/air mixture entering or resident within the pre-combustion chamber and/or the central channel. 
         [0063]    In a still further embodiment of the present invention, the flame cone and the spark plug may be either manufactured as a unitary module or may be permanently joined to one another in the area of their respective adjacent ends. Among other things, this embodiment may permit use of the existing hex-sided body portion of the conventional spark plug as the location for application of a tool for rotationally inserting the unitary module within the throughbore. It will be recognized by one skilled in the art that the formation of the throughbore and the ignition chamber, and at least a portion or potentially all of the channels associated with the transfer of the initial flame front from the pre-combustion chamber to the combustion chamber, also may be by means of a casting of the engine head. 
         [0064]    As noted, in the embodiment depicted in  FIG. 11 , there is no flame cone involved, per se. Rather, the throughbore is cast or machined as an integral part of the head, including variations in diameters of different portions of the throughbore and/or internal threads for that end of the throughbore which receives a spark plug therein. 
         [0065]    Whereas there is described herein one embodiment of an ICE combustion chamber of a given geometry, it will be recognized that the present invention is not limited to a particular geometry of the combustion chamber. In some ICEs, the intake valve is located at a location within the combustion chamber whereby the flame front exiting the central channel will need to be angled toward the intake valve as opposed to the flame front exiting the central channel along a straight path coincident with the longitudinal centerline of the central channel. Likewise, the location of the exhaust valve may be altered from that shown in figures. In any event, the path of the flame front exiting the central channel is to be aligned such that the flame front assumes a direct path from its exit port from the central channel to its intended operative destination. In other embodiments of a combustion chamber, the distances between the intake valve and the exhaust valve may vary. In such embodiments, consideration must be take of the need for propagation of the combustion within the combustion chamber to follow the pattern set forth herein in order to achieve maximization of the buildup of heat and pressure within the combustion chamber at the herein described timing with respect to the rotational position of the crankshaft, for achieving the described advantages of energy conversion to work for driving the piston within its cylinder. 
         [0066]    Similarly, whereas that channel in the flame cone leading directly from the pre-combustion chamber to the combustion chamber is referred to herein as a “central” or “first central” channel, it will be recognized that this first central channel need not be “central” of the flame cone (i.e., its longitudinal centerline may be offset from the longitudinal centerline of the flame cone).