Abstract:
An internal combustion engine having a combustion chamber incorporates a fuel conditioner and injector employs a vessel having a wall exposed within the combustion chamber to be heated by combusting fuel. The vessel encompasses an expansion chamber and has at least one open fuel injection passage through the wall into combustion chamber. An inlet conduit receives liquid fuel at a predetermined pressure from a fuel delivery system. A nozzle interconnects the inlet conduit and the expansion chamber. A pin operably seals the nozzle for timed injection of liquid fuel into the expansion chamber. An operator actuates the pin from a closed position sealing the nozzle to an open position placing the fuel injection volume in fluid communication with the expansion chamber. Liquid fuel injected into the expansion chamber at a predetermined time is simultaneously adiabatically heated, and pressurized to a state above a critical point using heat in the vessel wall and self-injects through the at least one open fuel injection passage into the combustion chamber of the engine.

Description:
BACKGROUND 
     Field of the Invention 
     The embodiments disclosed herein relate generally to fuel systems for an any internal combustion engines and more particularly to a fuel conditioning and injection system employing a volume in contact with combustion temperatures for adiabatic heating of fuel pumped into the chamber at a fuel rail pressure to high pressure and temperature and conversion of at least a portion of the fuel into more highly energized radical molecules for self-injection through open orifices into the combustion chamber of the engine. The open orifices allow partial oxidation of the fuel charge during adiabatic heating for formation of radicals improving combustion performance. 
     References to Related Art 
     Internal combustion engines, and more particularly compression-ignition engines, also known as a Diesel cycle engines, perform at maximum output and efficiency when the maximum combustion pressure occurs in a desired rotation range of the engine crank shaft somewhere between 20 and 30 degrees after top dead center (TDC) down in the working cycle. There is a measurable time lag between the point of fuel injection into the combustion chamber and combustion occurring, which is known as ignition delay. Fuel must be injected earlier to have time to ignite and combust developing maximum pressure at the desired rotation range. In most compression-ignition engines the fuel is injected into combustion chamber and starts raising pressure in the combustion chamber before the engine has completed the compression cycle, which is necessary to obtain the peak combustion pressure in the desired rotation range. This negatively affects life of the engine due to overloading and also produces noise known as “knock”. In these engines, if fuel was injected after the compression cycle to eliminate the knock, then maximum combustion pressure will develop at greater than the desired 20-30 degrees of working cycle of the crank shaft, wasting combustion energy through the exhaust cycle and resulting in output and efficiency losses. Alternatively, the engine can be switched to a different fuel quality or cetane number to reduce ignition delay. 
     It is known in the prior art that compression-ignition engines working on gasoline are far more efficient compared to gasoline powered Otto cycle engines. However, such engines produce a power output only about 75% of an Otto cycle engine of equal displacement. Prior art compression-ignition engines do not provide homogeneous mixture of fuel with oxidizing atmosphere prior to combustion, and the greater amount of fuel after a certain level being injected into the engine creates incomplete fuel burn, resulting in unacceptable emission levels. 
     It is also known that higher efficiency can be obtained by conditioning fuel to a high energy state prior to introduction into the combustion chamber of the engine, and more particularly preheating, pressurizing and partially oxidizing the fuel to a vapor and above a critical state with an optimal ratio of fuel molecules in radical formation. It has been well established that only molecules in radical formation ignite and combust and that ignition delay is the time interval between introduction of the fuel into an oxidizing atmosphere, fuel transformation in several states to form radicals and initial oxidation of the radicals that is combustion. Parameters affecting transformation of the fuel molecules to formation of the radicals are heating the fuel to the temperature exceeding 1000 F. with initial pressure applied, or heating the fuel molecules above critical temperature and critical pressure for particular type of fuel with partially oxidation. The ignition and following combustion occurring from oxidizing fuel radicals in high concentration of oxygen constituting the combustion event is independent from the temperature of the oxidizer. Somewhat different from pure compression-ignition engines, this type of engine operation is called injection-ignition. It has also been found that radicals have four times higher ability to mix with oxidizer, providing a more homogeneous mixture and providing ability to increase power density of an engine. 
     It is therefore desirable to provide a conditioner and injector system for engines to have a negligible ignition delay where fuel can be injected after the compression cycle with combustion maximum pressure reached between 20 and 30 degrees after piston TDC down in the working cycle main operating shaft rotation with the engine performing at a maximum efficiency without knock. It is also desirable to provide a greater power density of the compression-ignition engines, for a particular engine displacement with any desired type of fuel and that engine displacement can be reduced with engine output requirements leading to reduce fuel consumption, reduced engine dimensions and weight thereby lowering manufacturing cost. It is also advantageous for the engine to have homogeneous mixture of fuel with oxidizing atmosphere prior combustion. It is still further advantageous for the conditioner and injector system to introduce fuel into the combustion chamber of the engine above critical state with an optimum level of radicals, instead of a liquid form at an engine environmental temperatures, thereby providing a greatly reduction ignition delay and increasing thermal efficiency of the combustion. 
     SUMMARY OF THE INVENTION 
     The embodiments disclosed herein provide a fuel conditioner and injector for an internal combustion engine having a combustion chamber. The fuel conditioner and injector employs a vessel having a wall exposed within the combustion chamber to be heated by combusting fuel. The vessel encompasses an expansion chamber and has at least one open fuel injection passage through the wall into the combustion chamber. An upper body having an inlet conduit receives liquid fuel at a predetermined pressure from a fuel delivery system. A nozzle interconnects the inlet conduit and the expansion chamber. A pin operably seals the nozzle for timed injection of liquid fuel into the expansion chamber. An operator actuates the pin from a closed position sealing the nozzle to an open position placing the fuel injection volume in fluid communication with the expansion chamber. Liquid fuel injected into the expansion chamber is adiabatically conditioned to above a critical point using heat in the vessel wall and self-injects through the at least one open fuel injection passage into the combustion chamber of the engine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a fragmentary side section view of a piston-reciprocating internal combustion engine with the piston position at a top dead center, showing an exemplary embodiment of the fuel conditioner and injector device; 
         FIG. 1B  is a partially sectioned pictorial view of an alternative embodiment as incorporated in an opposing piston engine; 
         FIG. 1C  is a partially sectioned pictorial view of an alternative embodiment incorporated in a rotary engine; 
         FIG. 2  is a simplified elevation view of an exterior of the fuel conditioner and injector device with a fragmentary sectional view of the injector valve and vessel with the expansion chamber for the embodiment of  FIG. 1A ; 
         FIG. 3  is an isometric view of the fuel conditioner and injector device; 
         FIG. 4  is an exploded isometric view of the fuel conditioner and injector device; 
         FIG. 5  is an enlarged side section view of the injector valve and vessel of the fuel conditioner and injector device shown in  FIG. 2 ; 
         FIG. 6  is a graph showing pressure in the cylinder of the engine and the expansion chamber of the fuel conditioner and injector device; and, 
         FIG. 7  is a block diagram of the controller and operator for the fuel injection pin. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments disclosed herein provide a fuel conditioner and injector device which uses combustion heat energy for adiabatically heating and pressurizing a liquid fuel to above a critical point from a lower temperature and pressure of a liquid fuel delivery system prior to fuel entry into a combustion chamber of the engine. This process is referred to herein generally as “conditioning” of the fuel. An inlet injector includes a body receiving fuel under pressure from the fuel delivery system. Fuel is injected from the body through at least one liquid fuel inlet passage into a vessel having an expansion chamber. The liquid fuel flow is controlled by a conventionally activated valve as known in the prior art. The vessel has an exterior surface which is exposed within the combustion chamber and has an expansion chamber with the ability to withstand high pressure and high temperature. The vessel absorbs combustion heat through the exterior surface with heat transfer to the vessel inner surface surrounding the expansion chamber. Injected liquid fuel introduced into expansion chamber absorbs heat energy from the inner surface and is transformed from a liquid phase into a high temperature and pressure phase above the critical point for the fuel inside the expansion chamber of the vessel. The vessel incorporates at least one open fuel injection passage from the expansion chamber into the combustion chamber and conditioned fuel under increasing pressure in the expansion chamber is automatically injected (“self-injected”) into the combustion chamber. The size of the open fuel injection passages or an orifice within the passages allows entry of oxygen rich charge air (and/or other supplemented oxidizer) from the compression cycle of the engine and constrains the exiting fuel flow for a desired flow time. During the adiabatic heating and pressurization process, injection of a compressed oxidizing atmosphere from the oxidizer charge being compressed in the engine into the expansion chamber from the combustion chamber through the open fuel injection passages results in partial oxidation of the fuel. The combination of heating of the fuel charge in the expansion chamber above the critical point by continuing absorption of heat from the vessel creates radicals in a portion of the fuel molecules with a higher energy state in the fuel charge. Partial oxidation of the fuel in creating the radicals in the fuel molecules releases internal energy in the heated fuel conditioned in the expansion chamber. In the exemplary embodiments sizing of the total area of the open fuel injection passages is predetermined for admitting sufficient oxidizer charge into the expansion chamber to induce formation of a small percentage of radicals without diluting the following combustion rate with up to 5% of the total fuel charge converted to radicals in the conditioned fuel for enhanced combustion in the exemplary embodiment. The conditioned fuel with the converted radicals is defined herein as a “hyper fuel state”. In alternative embodiments, injection through the fuel injection passage may be controlled by a secondary valve operating independently from the valve in the injector body to adjust timing of injection flow. The present invention is provides reduction in ignition delay and improves quality of the combustion process, which ultimately leads to increases in fuel efficiency and reduction of harmful emissions of the combustion engine. 
     Referring to the drawings,  FIG. 1A  illustrates as a first example an engine  10  employing an exemplary embodiment of the fuel conditioner and injector device. The engine  10  incorporates a cylinder  11  in which a piston  12  reciprocates on a piston pin  13  driving a connecting rod  14  conventionally attached to a crank shaft (not shown). A cylinder head  15  closes the cylinder  11  and provides a combustion chamber  16 . The fuel conditioner and injector device  100  is received in the cylinder head  15 . While shown as a separate integrated element portions of the conditioner and injector device  100  may be machined into or otherwise integrated with the cylinder head  15 . As also seen in  FIGS. 2-3 , the fuel conditioner and injector device  100  includes an upper portion  101  which incorporates actuating elements and connection to the liquid fuel delivery system as will be described in greater detail subsequently. A lower portion  102  has a vessel  105  having at least a portion of an exterior wall  104  as a heat absorbing surface exposed within the combustion chamber  16 . 
     As seen in  FIGS. 4 and 5 , an expansion chamber  103  in the vessel  105  is formed in an exemplary embodiment by a lower portion  107  and a cap  108  integrated in the conditioner and injector device. In alternative embodiments, the vessel  105  may be a separate element or may be machined into the cylinder head  15 . A pin  109  is constrained in a lower body  110  with an upper body  112 . Liquid fuel from the fuel delivery system flows through an inlet conduit formed in the exemplary embodiment by a fuel inlet passage  113   a  from a fuel gallery  113   b  into a fuel injection volume  113   c . The pin  109  operably seals a liquid fuel inlet nozzle  114  in the cap  108  which is in fluid communication between the fuel injection volume  113   c  and the expansion chamber  103 . A seat  115  in the fuel inlet nozzle allows a mating seal with the pin  109 . Open fuel injection passages  111  extend through the wall  104  from the expansion chamber  103  into the combustion chamber  16 . 
     The lower portion  107  of the vessel  105  and the exterior wall  104  are shaped to provide desired amount of absorption of heat from the combustion chamber  16  during operation of the engine  10  and transfer of that heat for adiabatic pressurization of a fuel charge provided through the inlet nozzle  114 . The vessel  105  and exposed wall  104  are centrally located in the combustion chamber  16  for even distribution of conditioned fuel through the open fuel injection passages  111  into the combustion chamber. The vessel  105  as a whole or the lower portion  107  may be fabricated from titanium for high thermal efficiency and strength. For the embodiment shown lower portion  107  and exterior wall  104  constitute a rounded nipple extending into the combustion chamber  16 . In alternative embodiments a hemispherical shape or other geometric protrusion may be employed. The interior expansion chamber  103  of the vessel  105  is shaped with a torus in the cap  108  blending into substantially a cone shape in the lower portion  107  to enhance mixing of the fuel injected into the expansion chamber through inlet nozzle  114 . Fuel injected into the cone shape is reflected upwards into the torus shape which then recirculates the fuel charge creating mixing within the entire expansion chamber to facilitate conditioning of the fuel. 
     Alternative engine structures may also be employed with the conditioner and injector device  100 . As a second example an opposed piston engine  210  is shown in  FIG. 1  B. Opposing pistons  212   a  and  212   b  operate in mutual reciprocating motion in a cylinder  211 . Connecting rods and other elements of the engine are known in the art and are not shown in detail in the drawings. The conditioner and injector device  100  is carried in the structure surrounding the cylinder  211  to allow the exterior wall  104  of the vessel  105  to be exposed within the central portion of the cylinder which constitutes the combustion chamber. Operation of the conditioner and injector device is substantially identical as for the embodiment described with respect to  FIG. 1A . 
     Similarly, the conditioner injector device  100  may be employed in a rotary engine  310  as illustrated in  FIG. 1C . The conditioner and injector device  100  is carried in the structure surrounding the engine operating chamber  311  in which rotor  312  circulates to allow the exterior wall  104  of the vessel  105  to be exposed within a recess  316  for communication with that portion of the operating chamber which constitutes the combustion chamber during rotation of the rotor  312 . 
     Embodiments of the conditioner and injector device  100  may also be employed in dynamic cam, wobble plate or axial engine formats. For the operating disclosure herein the term cylinder head as applicable to a conventional piston engine is intended to include comparable structure surrounding the combustion chamber in alternative engine formats. Similarly, the crank shaft as applicable to a conventional piston engine is intended to include the main operating shaft or other similar main power transmission element receiving power from the operating elements such as the piston or rotor and references to rotational positions of the crank shaft are intended to represent comparative portion of the compression and combustion cycle in alternative engine forms. 
     An exemplary embodiment of an engine employing the fuel conditioner and injector device for the engine of  FIG. 1A  incorporates one cylinder with a swept volume of 600 cc having 96 mm bore and 82 mm stroke. Engine fuel type is 103 octane gasoline. During operation cylinder pressures for the exemplary embodiment reach a maximum of approximately 3.59 MPa (520 psi) during the compression cycle. Temperatures generated by the combusting fuel/air charge reach approximately 4,000° F. The engine has a maximum operating condition of 7,000 RPM employing a fuel charge of 3.0 cubic mm (10 −3  ml). Heating of the vessel  105  by the cylinder combustion to at least 1000° F. is desirable with approximately 2,500° F. being reached with the engine operating at maximum RPM with full fuel charge. Volume of the expansion chamber  103  in the vessel  105  is larger than the volume of injected liquid fuel and for the exemplary embodiment is 1766 cubic mm (1.766 cc) in the exemplary embodiment to accommodate the 3.0 cubic mm liquid fuel volume for injection and provide sufficient volume for adiabatic pressurization of the fuel charge for injection. The surface area of the wall  104  of the vessel  105  is 440 mm 2  to provide the necessary heat transfer from the combustion chamber to the expansion chamber  103  to achieve the adiabatic conditioning of the fuel beyond the critical point. The fuel delivery system providing liquid fuel to the fuel inlet passage  113   a  operates in the exemplary engine at 24.1 MPa (3500 psi) A minimum operating pressure of the fuel delivery system of at least 4 MPa (580 psi) (approximately 12% over maximum cylinder compression pressure) is desirable and exemplary systems may operate at between 4.13 MPa (600 psi) and the present example operating pressure of 24.1 MPa. The liquid fuel inlet nozzle  114  sealed by pin  109  has a diameter of 0.4 mm for the exemplary embodiment to achieve injection of the liquid fuel within the desire time delay. Operation of the pin  109  may be accomplished by electromechanical components in the upper portion  101  of the conditioner and injector device  100  such as a solenoid or piezo element operated by a microcomputer controller to achieve desired opening and closing of the liquid fuel inlet nozzle  114  by the pin  109 . Six open fuel injection passages  111  from the expansion chamber  103  in the vessel  105 , each with a diameter of 0.22 mm, are employed in the exemplary embodiment giving a total area of 0.23 mm 2 . This area is optimized for the exemplary embodiment to allow oxidizer charge admission into the expansion chamber  103  during the compression cycle for creating radicals in the fuel during conditioning to create a hyper fuel state and to allow injection of the conditioned fuel over the desired time period for combustion as described in detail below. 
     Operation of the engine is best described in terms of timing based on rotation of the crank shaft. Operating at 7,000 RPM, the crank shaft transits 1° of angular rotation in 23.8 microseconds. For maximum efficiency, combustion of the fuel charge occurs over a desired range between 20° and approximately 50° after TDC. This results in a desired combustion time of 714 microseconds. Fuel introduced into the expansion chamber  103  must have sufficient time to expand and pressurize with resulting injection through the fuel injection passages and timing must accommodate ignition delay. Projected combustion maximum pressures occur at approximately 30° after TDC. Adiabatic pressurization of the fuel charge in the expansion volume provides a peak injection pressure which then decays during injection of the conditioned fuel into the cylinder. The volume of the expansion chamber is designed to be much greater then volume of the injected fuel. The pressure in the expansion chamber from adiabatic expansion of injected fuel absorbing heat and partially oxidizing (as will be described subsequently) depends also on the expansion chamber volume. A smaller volume of the expansion chamber and higher temperature creates higher peak pressure in the expansion chamber and also will reduce the time of the fuel injection into combustion chamber, which will reduce combustion time. Sizing of the expansion chamber  103  is determined to create the desired pressure and temperature above the critical point for the fuel with the projected combustion rate. 
     Based on the structure described for the exemplary embodiment, the injection time of the liquid fuel injection into expansion chamber  103  calculated based on operating pressure of the fuel supply system, the amount of maximum fuel volume of 3 cubic mm, size of the liquid fuel inlet nozzle  114  and fuel environmental temperature is approximately 119 microseconds, which equals around 5° rotation of the crankshaft at 7,000 RPM. It should be noted that the injection time into expansion chamber (119 microseconds) must be less than a delay time of the increasing pressure in the expansion chamber to the equal the pressure supply system for preventing back flow of the fuel and sizing of the fuel inlet nozzle is determined to allow completion of the liquid fuel injection within that constraint. The injector nozzle pin  109  must be closed to seal the liquid fuel inlet nozzle  114  before of the pressure in the expansion chamber exceeds the fuel supply delivery pressure. In the exemplary embodiment expansion of the fuel charge takes approximately 345 microseconds to increase to 3.59 MPa (520 psi). The 119 microseconds of the injection time for the liquid fuel into expansion chamber therefore avoids any backflow of fuel from the expansion chamber into the fuel supply system. Within the 345 microseconds, the fuel charge is conditioned above the critical point and creation of radicals to provide the hyper fuel state occurs within approximately the last 60 microseconds (2.5° of crank rotation) 
     When the pressure in the expansion chamber exceeds the 3.59 MPa (520 psi) threshold equal to compression pressure of the oxidizer charge in the engine, “self-injection” of conditioned fuel automatically commences through the open fuel injection passages  111  from the expansion chamber  103  into the combustion chamber  16 . To accommodate the delay time, 345 microseconds, for the fuel charge to expand and pressurize in the expansion chamber for initiating injection, opening of the injection nozzle pin  109  must occur 15° prior to the desired commencement of combustion starting point at 20° after TDC. Additionally, a combustion delay of approximately 12 microseconds or approximately 0.5° of crankshaft rotation must be accommodated. Liquid fuel injection into the expansion chamber is previously noted as 119 microseconds or 5° of rotation which occurs within the 14.5° required for the fuel charge pressurization to 3.59 MPa (520 psi). Therefore, in the exemplary embodiment, initiation of the liquid fuel injection by opening of the injection nozzle pin  109  must occur at approximately 5° after TDC.  FIG. 6  demonstrates the pressures in the engine cylinder, trace  602  and expansion chamber, trace  604  over the operating cycle of the piston as described above. Area of the open fuel injection passages is determined to create a combustion rate providing the desired fuel combustion cycle between 20° and 50° of crankshaft rotation in the example engine. 
     The open fuel injection passages  111  provide an additional benefit in that during the compression cycle of the oxidizer charge, compressed oxidizer is forced through the passages into the expansion chamber  103  to provide oxygen for creation of radicals in the fuel charge as the fuel is injected into the expansion chamber and is adiabatically pressurized and conditioned to a state above the critical point for the fuel. The oxidizer charge in a conventional engine may be pressurized air but may include injected nitrous oxide or other additive for enhanced performance. The total opening of the passages which communicate between the expansion chamber and the combustion chamber is determined such that a desired amount of compressed oxidizer is introduced from cylinder during the compression cycle. Partial oxidation of the fuel injected into expansion chamber will energize the fuel by creating molecules in radical formation therein without diluting fuel energy, which would lower the combustion efficiency. This operation allows the exemplary embodiment of the engine to operate as an injection ignition engine wherein the ignition and following combustion occurs from oxidizing of heated fuel to a state above a critical point in high concentration of oxygen, and that combustion event is independent of temperature of the oxidizer. This method of operation also greatly reduces or completely illuminates carbon coke formation of the fuel which has been conditioned to hyper fuel with molecules in radical formation, which may cause clogging injector nozzles and fuel passages. The introduction of fuel radicals into oxidizer present in the combustion chamber occurs substantially immediately upon fuel activation and transformation into the radical state, which prevents carbon coke formation. 
     For engine operation at the medium and lower RPM, all fuel injection requirements described above are adjusted automatically for normal operation of the engine. Because the engine operates from regulated amount of the injected fuel, a lower fuel volume results in less combustion temperature, a lower volume of oxidizer injected into expansion chamber, less heat transfer to the fuel and less pressure in the expansion chamber, lower engine RPM with more combustion time at approximately the same desire range between 20° and 50° of crankshaft rotation for the combustion process to maintain the combustion maximum pressure at 30°. 
     For the exemplary embodiment, cold start conditions of the engine may be accommodated by a cold start fuel injector  17  and glow plug  18  as seen in  FIG. 1  to allow temperature stabilization of the engine for conditioning of the vessel  105  to provide appropriate temperatures for heating and expanding fuel in the expansion chamber  103 . Alternatively electrical coils (not shown) may be placed inside the expansion chamber  103  to augment the heating capability of the vessel  105 . 
     As seen in  FIG. 7 , an engine controller  702  provides timing control for the injection of fuel into the expansion chamber  103  by the pin  109 . The engine controller is operable connected to an electromechanical operator  704  such as a solenoid or piezo actuator in the upper portion  101  of the fuel conditioner and injector  100 . Upon powering of the operator  704 , pin  109  is displaced from the seat  115  to open the nozzle  114  allowing liquid fuel from the pressurized liquid fuel supply system  706  connected through the gallery  113   b  through fuel passage  113   a  to be injected from the injection volume  113   c  into the expansion chamber  103  (as previously described with respect to  FIG. 5 ). While described herein as an electromechanical operator, a purely mechanical actuation system may be employed. 
     Having now described various embodiments of the disclosure in detail as required by the patent statutes, those skilled in the art will recognize modifications and substitutions to the specific embodiments disclosed herein. Such modifications are within the scope and intent of the present disclosure as defined in the following claims.