Ignition apparatus and method for an internal combustion engine
BACKGROUND 
     1. Field of the Invention 
     This invention relates to a torch plug ignition apparatus and method for an internal combustion engine. 
     2. The Prior Art 
     The conventional internal combustion engine utilizes an electrical spark plug as an ignition source for the fuel/air mixture compressed in each cylinder of the engine. The relatively low ignition efficiency of a conventional spark plug requires a relatively rich fuel/air mixture in order to sustain ignition. Accordingly, it is customary to provide an excess of fuel or an approximate fuel-to-air ratio of about 1:8 (1 part vaporized fuel to 8 parts air). However, this fuel/air ratio is substantially in excess of an optimum fuel/air ratio for the appropriate combustion and expansion of the combustion products in the cylinder. It is currently believed that an optimum fuel/air ratio may be as low as 1:40-50. 
     In recognition of this feature, recent developments in internal combustion engines and, more particularly, the carburetion therefor, has led to the development of what is referred to in the art as the &#34;stratified charge&#34; system. The stratified charge system involves providing a layer or strata of richer fuel/air mixture in the vicinity of the spark plug with the fuel/air mixture becoming progressively leaner further away from the spark plug. Spark ignition is initiated in the adjacent, richer mixture where its ignition provides a flame as the basis for igniting the remaining leaner mixture in the cylinder. Accordingly, the stratified charge more efficiently ignites the remaining, lean fuel/air mixture. This technique provides certain economies in fuel consumption but requires that the carburetion system and the engine be specifically designed to produce a stratified charge and thereby does not readily lend itself to incorporation into existing internal combustion engines through either simple modification or retrofit procedures. 
     It would, therefore, be an improvement in the art to provide a torch ignition device which can be inserted into the existing spark plug opening. The torch ignition system should propel a torch of flame which will ignite a lean fuel/air mixture, the lean fuel/air mixture being substantially leaner than can be suitably ignited by a conventional spark plug. 
     An even still further advancement in the art would be to provide an ignition system for an internal combustion engine wherein certain physical laws in a preselected order are advantageously utilized to obviate the use of mechanical means for introducing fuel into the torch chamber of the ignition system. Such an invention is disclosed and claimed herein. 
     BRIEF SUMMARY AND OBJECTS OF THE INVENTION 
     The present invention relates to an apparatus and method for propelling a jet of burning fuel into the combustion chamber of a cylinder of an internal combustion engine. The jet of burning fuel is ignited by a spark in a torch chamber and propelled through a torch nozzle into the combustion chamber. The torch nozzle includes a constricted orifice or venturi section which shapes the flame from the torch chamber. A porous plug is interposed in the fuel supply line to the torch chamber to resist the immediate reverse flow action from combustion pressures and thereby create the appropriate unidirectional valving action for the fuel. The fuel is vaporized downstream of the porous plug and the pressure developed thereby used to force the fuel vapor into the torch chamber of the ignition apparatus. Cooling and shielding means are provided for the fuel supply apparatus to inhibit the premature vaporization of fuel. 
     It is, therefore, a primary object of this invention to provide improvements in ignition apparatus for an internal combustion engine. 
     Another object of this invention is to provide an improved method for igniting a lean fuel/air mixture in a cylinder of an internal combustion engine. 
     Another object of this invention is to provide an improved ignition system whereby an ignition flame is injected into the cylinder of an internal combustion engine to serve as the ignition source in place of the conventional spark plug. 
     Another object of this invention is to provide a unidirectional valving means for introducing fuel into a torch chamber of the ignition system whereby the valving action is achieved in the absence of mechanical valving structure. 
     An even still further object of this invention is to provide a cooling and shielding means for the fuel supply line to the ignition apparatus to inhibit the premature vaporization of the fuel. 
     These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompanying drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a perspective view of one presently preferred embodiment of the heat shield and torch chamber apparatus of this invention; 
     FIG. 2 is an exploded side elevation of the invention of FIG. 1 with portions broken away to reveal internal components; 
     FIG. 3 is an enlarged, cross section taken along lines 3--3 of FIG. 2; 
     FIG. 4 is an enlarged, partial plan view taken along lines 4--4 of FIG. 2; and 
     FIG. 5 is a cross section of a second preferred shielding and cooling embodiment for the fuel vaporization system of this invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention is best understood by reference to the figures wherein like parts are designated with like numerals throughout. 
     General 
     The present invention includes a torch nozzle which is adapted to be screwed at one end into a conventional spark plug opening in an engine block of an internal combustion engine. The other end of the torch nozzle is adapted to receive a spark plug and thereby form a torch chamber about the electrodes or spark gap of the spark plug. Means are included for introducing air and vaporized fuel into the torch chamber where they are mixed and the fuel/air mixture ignited by a spark at the spark gap. The pressures resulting from the ignition of the fuel/air in the torch chamber causes the burning fuel to be propelled from the torch chamber as a jet of flame into the cylinder of the internal combustion engine. The flame provides suitable ignition in the cylinder of a second fuel/air mixture having a significantly reduced fuel content thereby adapting the internal combustion engine for a surpisingly reduced fuel consumption. 
     Fuel for the torch chamber is supplied through a separate fuel line and is forced through a porous plug interposed in the fuel line. The porous plug acts as a solid state, one-way valve mechanism to assure unidirectional fuel flow toward the torch chamber. The porous plug allows liquid fuel to seep therethrough at a rate generally proportional to the pressure exerted on the fuel. The porous plug resists cyclic reverse flow of fuel and fuel vapor under the elevated back pressures from the combustion sequence. The minute capillary-like passages in the porous plug through which the fuel seeps thereby impose a damping effect on the cyclic elevated fuel vapor back pressures without significantly interfering with the flow of fuel therethrough. 
     Since the torch ignition apparatus of this invention operates in a high temperature environment resulting from the combustion of fuel in both the torch chamber and the internal combustion engine, various shielding and cooling modifications are included in the apparatus to inhibit vapor lock from premature vaporization of the fuel upstream of the porous plug. Once the fuel has passed through the porous plug, means are included for conducting a portion of the resultant heat into the fuel and vaporizing the same. The pressure developed by the vaporized fuel diffuses the fuel vapor into the torch chamber where it is mixed with air and subjected to cyclic ignition from the spark plug. 
     Referring now more particularly to FIGS. 1 and 2, one presently preferred embodiment of the apparatus of this invention is shown as a torch nozzle 14 which is adapted to receive at threads 44 the threads 24 of a suitably modified spark plug 20 and thereby enclose a spark gap 22 of spark plug 20 in a torch chamber 28. Torch nozzle 14 is specifically configurated with threads 34 to be screwed into a conventional spark plug opening in the engine block (not shown) of an internal combustion engine (not shown). Facets 15 permit a wrench (not shown) to be applied to torch nozzle 14 for tightening or loosening and removing the same. 
     Torch nozzle 14 includes a constricted passageway orifice or throat 40 between a convergent conical surface 32 which forms the forward end of torch chamber 28 and a divergent conical surface 42 which forms the entrance to the cylinder combustion chamber (not shown). The venturi thus formed is believed to suitably shape the flame propelled from the torch chamber 28. 
     Spark plug 20 and, more particularly, torch chamber 28 is modified with an air inlet 26. Air from a blower (not shown) is forced into air tube 46 as indicated at 47 and, thereafter, into torch chamber 28 through air inlet 26. Advantageously, a vortex mixing action of fuel with air in torch chamber 28 can be readily achieved by forming air inlet 26 as a tangential entry. Alternatively, inlet 26 can be formed into a side of torch nozzle 14 so as to penetrate convergent surface 32 and thereby suitably supply air to torch chamber 28. 
     Vaporized fuel is supplied to torch chamber 28 by a fuel vaporizer apparatus 60. The vaporized fuel is introduced into torch chamber 28 through fuel inlet 30. The fuel/air mixture in torch chamber 28 is ignited by a spark across spark gap 22. Electrical energy for the spark is supplied through an electrical lead 48, the supply of electrical energy and subsequent spark-initiated ignition in torch chamber 28 being suitably timed according to conventional techniques. 
     Fuel for the fuel vaporizer apparatus 60 is supplied as indicated at arrow 51 through a fuel line 50 connected to a nipple 62. Nipple 62 has a throughbore 63 and screws into a coupling 64. Coupling 64 serves as an enlarged housing for a porous plug 66 which is interposed in the fuel flow path through coupling 64. Porous plug 66 is fabricated from a substance such as carbon and has sufficient capillary-like passageways therethrough so as to permit the seepage of fuel at a rate generally proportional to the pressure imposed on fuel 51. 
     Coupling 64 terminates in an antechamber 65 which is in fluid communication with a diametrally reduced, cylindrical tube 69. Tube 69 connects coupling 64 to a block 80 and includes a throughbore 67 which provides fluid communication between antechamber 65 and a vapor channel 74 in block 80. The entrance to tube 69 is embedded in heat exchange relationship with a coolant channel 68 while the remainder of tube 69 projects from coolant channel 68 as narrow neck 71. Narrow neck 71 assists in at least partially thermally isolating coolant channel 68 from thermal energy transmitted by block 80. In particular, narrow neck 71 presents a relatively small cross section for heat conductance from block 80 while, simultaneously, fuel in throughbore 67 serves to absorb heat energy from the walls of narrow neck 71. 
     Referring now more particularly to FIGS. 3 and 4, a first preferred cooling embodiment for inhibiting the premature vaporization of fuel in vaporization apparatus 60 is illustrated. Water is the preferred cooling medium and flows through an inlet 52 into coolant channel 68 as indicated at 53 and departs from coolant channel 68 as indicated at 55 through water outlet 54. coolant channel 68 is formed as an elongated channel which surrounds the entrance to tube 69 thereby isolating fuel in coupling 64 from thermal energy emanating from block 80. 
     Block 80 is configurated as a solid block of metal and acts as a heat sink to thereby assure that the fuel passing therethrough is maintained in the vapor phase. Block 80 includes a neck 82 which is adapted to be threaded into mating threads in a raised boss 31 protruding from spark plug 20 to accommodate mounting fuel vaporizer apparatus 60 on spark plug 20. Neck 82 has a gasket 84 around its base which forms a seal between boss 31 and block 80. 
     Neck 82 surrounds and supports a ceramic plug 78 in a spaced relationship to form therebetween a narrow annular space, annulus 76. Ceramic plug 78 is formed from a ceramic material or other high refractory material to withstand the high temperatures from torch chamber 28 which pass through fuel inlet 30. Vaporized fuel from vapor channel 74 passes through annulus 76 and, thereafter, through inlet 30 into torch chamber 28. Additional vaporized fuel passages are provided by channels 77 (see FIG. 4) surrounding ceramic plug 78. Ceramic plug 78 thereby serves as a diffuser for diffusing vaporized fuel to inlet 30 through annulus 76 and channels 77 (FIG. 4). 
     Vaporization of fuel in throughbore 67 is attained by a vaporizer pin 70 which is inserted into throughbore 67 from block 80 to conduct thermal energy from block 80. Vaporizer pin 70 is diametrally reduced from the internal walls of throughbore 67 so as to provide an annular space through which the vaporized fuel passes to vapor channel 74. As the fuel is vaporized, it expands considerably and forces vaporized fuel through the vaporizer apparatus 60 into torch chamber 28. 
     Vaporizer pin 70 passes through a reduced opening in block 80 which forms a seat against which an enlarged head 73 of vaporizer pin 70 which is compressed so as to seal the end of throughbore 67 and provide good thermal contact between block 80 and vaporizer pin 70. A set screw 72 is used to compress head 73 against the seat in block 80. 
     Referring again to FIGS. 1 and 2, one embodiment for a heat shielding and cooling apparatus is shown in the form of a heat shield 16 and a cooling jacket 12. Heat shield 16 is fabricated from a high thermal conductivity metal such as copper, brass or the like and is formed with a cup-like shape having a rim 36 and an aperture 17 in the center of the base thereof. Threaded section 24 of spark plug 20 is passed through aperture 17 and screwed into threads 44 of torch nozzle 14 thereby clamping heat shield 16 between spark plug 20 and torch nozzle 14. By being clamped securely between spark plug 20 and torch nozzle 14, heat shield 16 is in good thermal contact with the same to conduct heat energy therefrom outwardly to rim 36. From rim 36 the heat is transmitted to a skirt 38 of cooling jacket 12. 
     Cooling jacket 12 and, more particularly, the circumferentially extending skirt 38 is configurated so as to telescopically receive rim 36 in snug press-fit relationship to (1) support cooling jacket 12 on heat shield 16 and (2) provide good thermal contact between rim 36 and skirt 38. Cooling jacket 12 includes a coolant channel 18 formed as a cylindrical annulus through which cooling water from an inlet tube 56 is introduced as indicated at arrow 57. A baffle 19 (shown in broken lines, FIG. 2) directs the cooling water downwardly adjacent skirt 38 as indicated at arrow 61 (shown in broken lines, FIG. 2) so as to increase the turbulence and the rate of heat absorption from skirt 38. The warm water departs from annular cooling channel 18 through an outlet 58 as indicated at 59. Water for cooling the various components in the ignition apparatus of this invention may be supplied from a cooling coil (not shown) inserted in the air conditioning system (not shown) or from any other suitable cooling source. 
     Referring now more particularly to FIG. 5, a second preferred embodiment for a fuel vaporizer apparatus of this invention including a heat shielding and cooling means is shown. In particular, a fuel vaporizer apparatus 100 includes a fuel line coupling 104 which serves as a housing for a porous plug 106 through which the fuel seeps into an antechamber 105. The fuel then passes into a cylindrical throughbore 107 passing through a tube 109. Porous plug 106 is similar to porous plug 66 (FIGS. 2 and 3) while cylindrical throughbore 107 and tube 109 are similar to throughbore 67 and tube 69, respectively (FIGS. 2-4). 
     Fuel vaporizer apparatus 100 is partially inserted into an air stream tube 86. Air stream tube 86 receives a continuous flow of air from a conventional blower (not shown) and includes a venturi 88 in the vicinity of antechamber 105. Air stream tube 86 is configurated as a coaxial tube about coupling 104 and accommodates a stream of cooling air, indicated as arrows 92, therethrough. The air stream is accelerated through venturi 88 and expands upon exiting therefrom so as to be cooled and thereby serve to absorb thermal energy from coupling 104, porous plug 106 and the fuel therein. Additionally, venturi 88 forces the air stream into a constricted stream of air which is also accelerated over the surface of coupling 104 so as to more rapidly remove thermal energy from the surface of coupling 104. The warm air exiting from air blast tube 86 is directed from a nozzle 90 away from spark splug apparatus 20 (FIG. 2) as a stream of warm air as indicated at 94. Air stream tube 86 acts as a heat shield about fuel line 50 by being formed as a coaxial tube about fuel inlet line 50 (FIGS. 1 and 2). It is, therefore, believed unnecessary to provide the vaporizer apparatus 100 with heat shield 16 and cooling jacket 12 thereby greatly simplifying the structure. 
     The remainder of vaporizer apparatus 100 including vaporizer pin 70, block 80, vapor channel 74, and set screw 72 and vaporizer pin head 73 are similar to that set forth with respect to the embodiment of FIGS. 2-4 and, accordingly, the same numbering designation is used for illustrating the various parts of the structure. It is, therefore, specifically understood that vaporizer apparatus 100 is attached to spark plug 20 by the same type of structure set forth in FIGS. 2-4. 
     The Method 
     In practicing the method of this invention, a spark plug 20 is modified by enclosing spark gap 22 in a torch chamber 28 into which an air inlet 26 and a vaporized fuel inlet 30 are provided. Spark gap 22 is enclosed by a torch nozzle 14 which is, in turn, secured by threads 44 in the conventional spark plug opening (not shown) in the internal combustion engine (not shown). 
     Where appropriate, vaporizer apparatus 60 or 100 and, more particularly, the liquid fuel entering therein, is suitably shielded and/or cooled so as to inhibit the premature vaporization of fuel. As the fuel passes into the appropriate vaporizer apparatus 60 or 100 downstream of porous plug 66 or 106, respectively, it is suitably vaporized by heat from vaporizer pin 70. The vaporized fuel is then diffused through fuel inlet 30 where it is combined with air from air inlet 26 to provide a richer, combustible fuel/air mixture in torch chamber 28. This fuel/air mixture in torch chamber 28 is periodically ignited by a spark across spark gap 22. The resulting rapid combustion of the fuel/air mixture creates an explosion which propels a jet of burning fuel through orifice 40 where it is dispersed throughout the lean fuel/air mixture in the combustion chamber (not shown) in the internal combustion engine (not shown). The relatively lean fuel/air mixture in the combustion chamber is obtained by suitably readjusting the carburetion system (not shown) and may also be augmented by injecting an additional volume of air directly into the combustion chamber. 
     The ignition in torch chamber 28 tends to be selfextinguishing against continued burning when there is no spark at spark gap 22. The momentary back pressure at both air inlet 26 and fuel inlet 30 momentarily stops the inflow of air and fuel thereby acting as a check valve to both components. Release of the back pressure allows the fuel and air to again enter and mix within torch chamber 28 through fuel inlet 30 and air inlet 26, respectively. 
     The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.