Abstract:
A nozzle injection apparatus for use in internal combustion engines includes a fuel pump for intermittently pressurizing fuel, an injection conduit in fluid communication with the fuel pump, the injection conduit permitting the pressurized fuel to be communicated to a fuel injection nozzle a control valve in fluid communication with the nozzle, wherein the control valve dynamically and selectively controls a pressure of said pressurized fuel within the injection conduit.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/413,719, filed on Nov. 15, 2010, entitled “CONTROLLED NOZZLE INJECTION METHOD AND APPARATUS,” which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates in general to a controlled nozzle injection method and apparatus, and deals more particularly with a controlled nozzle injection method and apparatus which operates to reduce the amount of polluting contaminants emitted by an internal combustion engine. 
     BACKGROUND OF THE INVENTION 
     Internal combustion engines are well known power generating devices which may have any number of differing configurations in dependence upon the type of fuel utilized, their size and the particular environment in which they are designed to operate. 
     Although several electronic fuel delivery systems for internal combustion vehicles are known to provide adequate performance characteristics, these systems tend to be expensive and do not address those motorized vehicles which include non-electronic fuel delivery systems. In those systems which utilize standard mechanical pumps for this purpose, there exists several inherent inefficiencies which the present invention seeks to address. 
     As can be seen in  FIG. 1 , a known fuel delivery system  10  of a typical high pressure, diesel engine utilizes a mechanical pump  12  (also referred to as a jerk pump or a block pump), and an unillustrated arrangement of camshafts and plungers, to intermittently provide a predetermined amount of fuel from a fuel supply  14  to a fuel injector  16  via an injection line. The nozzle of the fuel injector  16  operates to atomize the fuel as it enters the high pressure air combustion chamber of the engine. 
     In operation, pressure within the fuel injector  16  continues to build as the pump  12  provides fuel to the fuel injector  16  at the onset of a given fuel delivery cycle. A spring biased injector valve  22 , typically a needle valve or the like of the fuel injector  16 , opens in response to the pressure building within the fuel injector  16 , thereby causing fuel to be dispensed through a series of passageways and into the vehicle&#39;s combustion chamber. 
       FIG. 2  is a graph illustrating the pressure at the nozzle portion of the fuel injector  16  during the fuel delivery cycle, wherein a slight drop in pressure can be seen to occur at the start of the injection process (in certain instances a slight change in the slope of the pressure curve may be seen, rather than an actual drop in pressure), although pressure continues to build at a desired rate after fuel injection has begun. Fuel will therefore continue to be delivered to the combustion chamber of the vehicle until the pressure within the fuel injector falls below the return spring biasing force of the injector valve  22 . In these known systems, residual fuel which is left in the nozzle portion of the fuel injector  16  after the injector valve  22  closes is typically vented from the nozzle portion via a nozzle leak-off valve, conduit or the like. In other systems, such as that of the present invention, the residual fuel is not vented and remains in the line until the next injection. 
     In such systems as described in conjunction with  FIGS. 1 and 2  above, the pressure of the fuel has a direct effect on how the fuel atomizes as it leaves the fuel injector  16  and enters the combustion chamber, and hence on how the fuel burns within the combustion chamber of the vehicle. Larger droplets of fuel are provided to the combustion chamber of the vehicle during those times when the pressure at the nozzle portion of the fuel injector  16  is comparatively low. These larger droplets tend to take longer to evaporate, mix and burn and therefore may not be able to completely combust within the combustion chamber before being exhausted therefrom. In addition, such large, low pressure and low velocity droplets may not make it to the distal side of the combustion chamber to mix with all the air. Such incomplete mixing and combustion aggravates pollution concerns, including the production of increased particulates, smoke, odor, hydrocarbons, carbon monoxide and the like. 
     It would therefore be advantageous to modify existing fuel delivery systems so as to reduce the generation of pollutants while increasing the efficiency of the fuel delivery system as a whole. Towards this end, the present invention seeks to raise the closing pressure of the injected fuel, while holding the starting pressure of the fuel injection at an elevated level. 
     It has been determined that by raising the closing pressure, the needle valve in the nozzles starts to close earlier as the pressure in the injection line begins to drop. The nozzle therefore tends to close completely before the line pressure goes to zero, thereby reducing the quantity of fuel injected at an undesirably low pressure. A problem exists in incorporating this pressure architecture with standard mechanical, or jerk, pumps because known mechanical pumps cannot reach the desired high opening and closing pressures to start at typical cranking speeds. 
     With the forgoing problems and concerns in mind, the present invention seeks to provide a controlled nozzle injection method and apparatus which operates in conjunction with known mechanical fuel pumps to reduce the amount of polluting contaminants emitted by an internal combustion engine. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a controlled nozzle injection device. 
     It is another object of the present invention to provide a controlled nozzle injection device which operates to reduce the amount of polluting contaminants emitted by an internal combustion engine. 
     It is another object of the present invention to provide a controlled nozzle injection device which elevates the pressure at the beginning of the fuel delivery cycle. 
     It is another object of the present invention to provide a controlled nozzle injection device which maintains higher pressures at the end of the fuel delivery cycle. 
     It is another object of the present invention to provide a controlled nozzle injection device that allows for the pressure at each nozzle to be independently, dynamically and selectively controlled. 
     According to one embodiment of the present invention, a nozzle injection apparatus for use in internal combustion engines includes a fuel pump for intermittently pressurizing fuel and an injection conduit in fluid communication with the fuel pump, the injection conduit permitting the pressurized fuel to be communicated to a fuel injection nozzle. A high pressure manifold in fluid communication with the fuel pump and the nozzle is also provided to accumulate the pressurized fuel which is residually left in the injection conduit between intermittent pressurizations of the fuel. 
     According to another embodiment of the present invention, a nozzle injection apparatus for use in internal combustion engines includes a fuel pump for intermittently pressurizing fuel, an injection conduit in fluid communication with the fuel pump, the injection conduit permitting the pressurized fuel to be communicated to a fuel injection nozzle a control valve in fluid communication with the nozzle, wherein the control valve dynamically and selectively controls a pressure of said pressurized fuel within the injection conduit. 
     These and other objectives of the present invention, and their preferred embodiments, shall become clear by consideration of the specification, claims and drawings taken as a whole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below: 
         FIG. 1  is a block diagram of a known fuel delivery system for internal combustion engines. 
         FIG. 2  is a graph illustrating the pressure at the nozzle portion of a fuel injector during the fuel delivery cycle according to the fuel delivery system of  FIG. 1 . 
         FIG. 3  illustrates a controlled nozzle injection apparatus according to one embodiment of the present invention. 
         FIG. 4  is an enlarged, partial cross-sectional view of a valve assembly utilized in the injection apparatus of  FIG. 3 . 
         FIG. 5  is a graph illustrating the pressure at the nozzle portion of a fuel injector during the fuel delivery cycle according to the nozzle injection apparatus of  FIG. 3 . 
         FIG. 6  illustrates a controlled nozzle injection apparatus according to another embodiment of the present invention. 
         FIG. 7  is an enlarged, partial cross-sectional view of a dual valve assembly utilized in the injection apparatus of  FIG. 6 . 
         FIG. 8  illustrates a controlled nozzle injection apparatus according to another embodiment of the present invention. 
         FIG. 9  is an enlarged, partial cross-sectional view of a dual valve assembly utilized in the injection apparatus of  FIG. 8 . 
         FIG. 10  is an enlarged view of area “A” of  FIG. 8  and depicts a control valve assembly utilized in the injection apparatus of  FIG. 8 . 
         FIG. 11  is partial cross-sectional view of a controlled nozzle injection apparatus according to one embodiment of the present invention. 
         FIG. 12  is a schematic view of a controlled nozzle injection system according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 3  illustrates a controlled nozzle injection apparatus  100  according to one embodiment of the present invention. As illustrated in  FIG. 3 , a fuel injection pump  112  is provided to intermittently supply the injection apparatus  100  with a pressurized stream of fuel, typically a hydrocarbon fuel comprising gasoline, diesel fuel or the like. The pump  112  operates to send streams of pressurized fuel through, in succession, a plurality of fuel transport conduits  114 , a high pressure manifold  116 , a plurality of fuel injection conduits  118  and, finally, to a plurality of fuel injector nozzles  120  which exhaust the fuel streams into an unillustrated combustion chamber of a vehicle. A fuel return conduit  122  is also provided for depressurizing the high pressure manifold  116 , as will be described in more detail later. 
     Each of the nozzles  120  typically include a known arrangement of needle valves or the like which, when subjected to a threshold pressure, will permit passage of the pressurized fuel into the combustion chamber. The nozzles  120  do not, however, include leak off valves, conduits or the like which are typically provided to known nozzle assemblies to evacuate residual fuel therefrom like (as discussed previously). The present embodiment utilizes such leakless nozzles in order to trap residual, pressurized fuel within the spring chamber of the needle valves for subsequent use, as will be described in more detail later. Moreover, although there are a discreet number of conduits and fuel injector nozzles shown in  FIG. 3 , it will be readily appreciated that the present invention contemplates the incorporation of any number of conduits or nozzles without departing from the broader aspects of the present invention. 
     Returning to  FIG. 3 , the high pressure manifold  116  is provided with a plurality of differing valve sets  125  which are utilized to control the flow and pressure of the fuel streams provided by the fuel pump  112 .  FIG. 4  is an enlarged, partial cross-sectional view of the valve sets  125  utilized to control the flow and pressure of the fuel streams in accordance with the present invention. 
     As shown in  FIG. 4 , a check valve assembly  126  works in concert with a spool valve assembly  128  and a pressure relief valve assembly  130  to bootstrap residual pressure left in the injection apparatus  100  at the conclusion of each fuel cycle back into the injection apparatus  100 . By doing so, the present invention seeks to maintain high fuel injection pressures at the end of the fuel delivery cycle, similar to the high injection pressures present at the beginning of the fuel delivery cycle. 
     Operation of the injection apparatus  100  will now be described in conjunction with  FIGS. 3 and 4 . At the beginning of an initial fuel delivery cycle, the fuel pump  112  pressurizes a predetermined amount of fuel from an unillustrated fuel supply. As best seen in  FIG. 4 , the pressurized fuel travels through the transport conduit  114  and pools in a spring chamber  124  of a check valve assembly  126 . Once the pressure within the spring chamber  124  overcomes the reverse biasing force of a check spring  132 , a check ball valve  134  will be displaced, thereby allowing the pressurized stream of fuel to pass through the injection conduit  118  on the way to the nozzles  120  where a needle valve, or the like, opens and releases an atomized fuel stream into the combustion chamber of a motorized vehicle. 
     As pressure within the spring chamber  124  lessens at the end of the initial fuel delivery cycle, the check ball valve  134  will reassume its blocking position leaving a measured amount of residual fuel, and therefore pressure, trapped in the injection conduits  118 . While known systems remove this residual pressure, the present invention redirects the remaining pressurized fuel to the high pressure manifold  116  for later use. Returning to  FIG. 4 , the residual pressurized fuel in the injection conduits  118  forces the spool valve assembly  128  to shift against the biasing force of a return spring  136  housed within the spring chamber  124 . A passageway is thereby created which allows the pressurized fuel to be redirected to the high pressure manifold  116  for later use, the spool valve assembly  128  subsequently reassuming its original position. At this point, the needle valves of the nozzles  120  are also exposed to the residual fuel pressure in the injection conduits  118  and, therefore, a small amount of pressurized fuel will leak into an unillustrated spring chamber of the nozzles  120 , and so the opening and closing pressures of the nozzles  120  will be somewhat higher for subsequent fuel deliver cycles. 
     As subsequent fuel delivery cycles are performed, the residual pressurized fuel will continue to be ‘boot-strapped’ into the high pressure manifold  116 , as described above, until the injection conduits  118  and the high pressure manifold  116  have reached and stabilized at a predetermined elevated pressure. In one particular design embodiment, the pressure of the injection lines  118  and the high pressure manifold  116  are designed to stabilize at approximately 4000 psi, whereby detrimentally higher pressures are guarded against through the action of the pressure relief valve assembly  130  which shunts excessive pressure back to the fuel pump  112  for later use via the fuel return line  122 . 
     As will now be appreciated, once a state has been reached in which the injection conduits  118  and the fuel manifold  116  have stabilized at a predetermined elevated pressure, each subsequent fuel delivery cycle will begin and end at a scaled pressure which is substantially higher than normal and higher than the predetermined elevated pressure. A graph illustrating the forgoing pressure architecture during operation of the injection apparatus  100  is shown in  FIG. 5 . As can be seen from  FIG. 5 , subsequent to the pressure within the injection conduits  118  and the fuel manifold  116  having stabilized, the pressure curve  150  has similar characteristics to the pressure curve of known fuel delivery systems, as illustrated previously in  FIG. 2 . In the present invention, however,  FIG. 5  illustrates how the pressure of the injected fuel remains high even during the later stages of each fuel delivery cycle, owing to the elevated pressure maintained in the high pressure manifold  116  and the injection conduits  118  as a result of the bootstrapping of pressurized fuel. 
     In particular, when comparing the pressure curve  50  of  FIG. 2  to the pressure curve  150  of  FIG. 5 , it will be apparent that the pressure at the nozzle at the onset of fuel injection may be represented by X that is, the dynamic pressure provided by the fuel pump which is sufficient to open the needle valve of the nozzle. In  FIG. 5 , owing to the bootstrapping of pressure and the use of leakless nozzles  120  (as described previously), the pressure at the nozzles  120  is represented by the residual pressure in the system, 4000 psi in  FIG. 5 , plus the dynamic pressure X provided by the fuel pump  112 . In this manner, the present invention ensures that high opening and closing pressures may be maintained at the nozzles  120  during operation of the vehicle, resulting in a more complete combustion of injected fuel and a corresponding reduction in the pollutants exhausted therefrom. 
     It is therefore an important aspect of the present invention that the fuel streams provided to the combustion chamber of a motorized vehicle are maintained at an elevated pressure, especially at the nozzles  120 , thereby ensuring a more complete combustion of these fuel streams and an associated reduction in exhausted polluting contaminants. 
     It is another aspect of the present invention that the injection apparatus  100  illustrated in  FIGS. 3 and 4  may be incorporated onto existing motorized vehicles without incurring significant expenses. In order to accommodate the present invention into existing fuel delivery systems, an electrically actuated valve  140 , typically a solenoid or the like, is provided to the pressure relief valve assembly  130 . The solenoid valve  140  is actuated to vacate pressure within the high pressure manifold  116  during the initial cranking of the motorized vehicle&#39;s engine, to be in conformance with the motorized vehicle&#39;s original pressure design parameters. Once the vehicle has started, the solenoid valve would again be actuated to enable the fuel delivery routine as described above. While the primary function of the solenoid valve  140  is to reduce the build-up of pressure during a starting operation, the present invention also contemplates actuating the solenoid valve  140  in order to lower the opening and closing pressures of the nozzles  120  during low idle to reduce idling noise and the like. 
     Moreover, it should be noted that any additional expense incurred as a result of the incorporation of the more intricate valve assemblies of the present invention, as shown in  FIG. 4 , may be substantially offset by a reduction in other fuel delivery system components. In particular, as no ‘leak-off’ capability must be directly attributed to the nozzles  120 , as is standard in known fuel delivery systems, there is no need to drill leak-off holes in the nozzles  120  and the associated tubing and hoses for such are correspondingly eliminated. The present invention is therefore less expensive to produce and install than existing systems, as well as being more efficient. 
     In certain circumstances, it may be necessary to adjust the tubing or conduit sizes, as well as the size of the nozzles  120  themselves, in order to make the injection apparatus  100  work as designed at all engine operating speeds and for all fuel delivery demands, and the present invention contemplates such modifications without departing from the broader aspects of the present invention. In particular, the present invention may require that the injection conduits have as much as a 40% larger diameter than is typically present in those systems which utilize hydraulic mechanical fuel pumps. This may be required to ensure that the total pressure at the fuel pump does not get too high. In operation, the pressure at the pump end of the injection conduits is approximately equal to the residual pressure within the conduits plus the dynamic pressure required to propagate the fuel wave down the conduits. The dynamic pressure therefore needs to be reduced, and since the dynamic pressure is approximately inversely proportional to the injection conduits&#39; internal area, the internal area of the injection conduits may need to be made larger, as mentioned above. 
     It is therefore another important aspect of the present invention that by increasing the internal area of the injection conduits, enhanced performance may be readily obtained at the nozzle end of the injection conduits as well. In practice, the pressure available to inject the pressurized fuel into the combustion chamber is again the sum of the residual pressure within the injection conduits and the dynamic pressures. A larger internal area of the injection conduits will therefore allow more pressurized fuel to be available to maintain pressure on the nozzle as the needle closes the nozzle at the end of a fuel delivery cycle. Larger injection conduits also reduce the frictional losses associated with the system. 
       FIG. 6  illustrates a controlled hydraulic nozzle injection apparatus  200  according to another embodiment of the present invention. As illustrated in  FIG. 6 , a fuel injection pump  212  is provided to intermittently supply the injection apparatus  200  with a pressurized stream of fuel, typically a hydrocarbon fuel comprising gasoline, diesel fuel or the like. The pump  212  operates to send streams of pressurized fuel through, in succession, a plurality of dual valve assemblies  226 , a plurality of fuel injection conduits  218  and, finally, to a plurality of fuel injector nozzles  220  which exhaust the fuel streams into an unillustrated combustion chamber of a vehicle. 
     Each of the nozzles  220  typically include a known arrangement of needle valves or the like which, when subjected to a threshold pressure, will permit passage of the pressurized fuel into the combustion chamber. Moreover, although there are a discreet number of conduits and fuel injector nozzles shown in  FIG. 6 , it will be readily appreciated that the present invention contemplates the incorporation of any number of conduits or nozzles without departing from the broader aspects of the present invention. 
     Returning to  FIG. 6 , a high pressure manifold  216  is provided and is connected to each of the leak-off conduits  222  of the nozzles  220  in order to assist in boot-strapping residual pressurized fuel, as will be described in more detail later. The high pressure manifold  216  is further connected to the fuel pump  212  via an electrically actuated valve, typically a solenoid or the like, and serves to vacate pressurized fuel from the high pressure manifold  216 , back to the fuel pump  212 , when necessary. 
     As more clearly illustrated in  FIG. 7 , the dual valve assembly  226  includes a check valve assembly  228  and a pressure relief valve assembly  230  which bootstraps residual pressure left in the injection apparatus  200  at the conclusion of each fuel cycle back into the injection apparatus  200 . By doing so, the present invention seeks to maintain high fuel injection pressures at the end of the fuel delivery cycle, similar to the high injection pressures present at the beginning of the fuel delivery cycle. 
     Operation of the injection apparatus  200  will now be described in conjunction with  FIGS. 6 and 7 . At the beginning of an initial fuel delivery cycle, the fuel pump  212  pressurizes a predetermined amount of fuel from an unillustrated fuel supply. As best seen in  FIG. 7 , once the pressurized fuel overcomes the biasing force of a check spring  232 , a check ball valve  234  will be displaced, thereby allowing the pressurized stream of fuel to pass through the injection conduits  218  on the way to the nozzles  220  where a needle valve, or the like, opens and releases an atomized fuel stream into the combustion chamber of a motorized vehicle. 
     At the end of the initial fuel delivery cycle, the check ball valve  234  will reassume its blocking position leaving a measured amount of residual fuel, and therefore pressure, trapped in the injection conduits  218 . While known systems remove this residual pressure, typically by the retraction volume in the delivery valves, the present invention arrests the remaining pressurized fuel by virtue of the pressure relief valve assembly  230 . Owing to this trapped, residual pressurized fuel in the injection conduits  218 , a small amount of the pressurized fuel will be shunted through the leak-off conduits  222  and into the high pressure manifold  216  for later use. The leakage of pressurized fuel into the high pressure manifold  216  affects subsequent movement of the needle valve in the nozzles  220 , and so the opening and closing pressures of the nozzles  220  will be somewhat higher for subsequent fuel deliver cycles. 
     As subsequent fuel delivery cycles are performed, the residual pressurized fuel will continue to be ‘boot-strapped’ into the high pressure manifold  216 , as described above, until the injection conduits  218  and the high pressure manifold  216  have reached and stabilized at a predetermined elevated pressure. In one particular design embodiment, the pressure of the injection lines  218  and the high pressure manifold  216  stabilize at approximately 4000 psi, whereby detrimentally higher pressures are guarded against through the action of the pressure relief valve assembly  230  which shunts excessive pressure back to the fuel pump  212  for later use via a fuel return path  223 . 
     As will now be appreciated, once a state has been reached in which the injection conduits  218  and the fuel manifold  216  have stabilized at a predetermined elevated pressure (approximately 4000 psi, in the example above), each subsequent fuel delivery cycle will begin and end at a scaled pressure which is substantially higher than normal and higher than the predetermined elevated pressure. A graph illustrating the forgoing pressure architecture during operation of the injection apparatus  200  can be seen in previously discussed  FIG. 5 . As can be seen from  FIG. 5 , although the pressure curve  150  has similar characteristics to the pressure curve  50  of known fuel delivery systems as illustrated previously in  FIGS. 1 and 2 , the pressure of the injected fuel remains high even during the later stages of each fuel delivery cycle, owing to the elevated pressure maintained in the high pressure manifold  216  and the injection conduits  218  as a result of the bootstrapping of pressurized fuel. 
     Similar to the operation of the injection apparatus  100  of  FIGS. 3 and 4 , the injection apparatus  200  ensures that the fuel streams provided to the combustion chamber of a motorized vehicle are maintained at an elevated pressure, especially at the nozzles  220 , thereby ensuring a more complete combustion of these fuel streams and an associated reduction in exhausted polluting contaminants. 
     Moreover, the injection apparatus  200  illustrated in  FIGS. 6 and 7  may be incorporated onto existing motorized vehicles without incurring significant expenses. In order to accommodate the injection apparatus  200  into existing fuel delivery systems, an electrically actuated valve  240 , typically a solenoid or the like, is provided between the high pressure manifold  216  and the fuel pump  212 . The solenoid valve  240  is actuated to vacate pressure within the high pressure manifold  216  during the initial cranking of the motorized vehicle&#39;s engine, to be in conformance with the motorized vehicle&#39;s original pressure design parameters. Once the vehicle has started, the solenoid valve  240  would again be actuated to enable the fuel delivery routine as described above. While the primary function of the solenoid valve  240  is to reduce the build-up of pressure during a starting operation, the present invention also contemplates actuating the solenoid valve  240  in order to lower the opening and closing pressures of the nozzles  220  during low idle to reduce idling noise and the like. 
     As best seen in  FIG. 6 , the injection apparatus  200  utilizes the leak-off conduits  222 , which are typically present in standard fuel delivery systems, to assist in the bootstrapping of pressurized fuel. The present invention may therefore be easily adapted to existing systems, as well as being more efficient. In certain circumstances, it may be necessary to adjust the tubing or conduit sizes, as well as the size of the nozzles  220  themselves, in order to make the injection apparatus  200  work as designed at all engine operating speeds and for all fuel delivery demands, and the present invention contemplates such modifications without departing from the broader aspects of the present invention, as discussed previously. 
     As can be seen from the foregoing disclosure and figures in combination, a controlled nozzle injection apparatus according to the present invention is advantageously provided with a plurality of beneficial operating attributes, including, but not limited to: enabling high starting pressure at the beginning of a fuel delivery cycle, maintaining higher end pressures at the conclusion of a fuel delivery cycle, reducing the exhaust of polluting contaminants and recycling excess pressurized fuel for later use. All of these attributes contribute to the efficient operation of an internal combustion engine and are especially beneficial in those situations where the retro-fitting of existing internal combustion engines are necessary in order to address ever increasingly stringent environmental concerns and regulations. 
       FIG. 8  illustrates a controlled hydraulic nozzle injection apparatus  300  according to yet another embodiment of the present invention. As shown therein, the injection apparatus  300  is similar to the apparatus  200  of  FIG. 6  in many respects. As with the injection apparatus of  FIG. 6 , a fuel injection pump  312  is provided to intermittently supply the injection apparatus  300  with a pressurized stream of fuel, typically a hydrocarbon fuel comprising gasoline, diesel fuel or the like. The pump  312  operates to send streams of pressurized fuel through, in succession, a plurality of dual valve assemblies  326 , a plurality of fuel injection conduits  318  and, finally, to a plurality of fuel injector nozzles  320  which exhaust the fuel streams into an unillustrated combustion chamber of a vehicle. 
     Each of the nozzles  320  typically include a known arrangement of needle valves or the like which, when subjected to a threshold pressure, will permit passage of the pressurized fuel into the combustion chamber. Moreover, as with the apparatus  200  of  FIG. 6 , although there are a discreet number of conduits  318  and fuel injector nozzles  320  shown in  FIG. 8 , it will be readily appreciated that the present invention contemplates the incorporation of any number of conduits or nozzles without departing from the broader aspects of the present invention. 
     A manifold  316  is provided and is connected to each of the leak-off conduits  322  of the nozzles  320  in order to assist in boot-strapping the residual pressurized fuel. The high pressure manifold  216  is further connected to the fuel pump  312  and serves to vacate pressurized fuel from the manifold  316 , back to the fuel pump  312 . 
     As will be readily appreciated, however, the apparatus  200  of  FIG. 6  may not necessarily be pressure balanced, i.e., the pressures in each of the nozzles  220  and injection conduits  218  may not necessarily be uniform. As shown in  FIG. 8 , in order to address any non-uniform pressures that may be present, each nozzle  320  is further configured with an electronic control valve and pressure sensor  323  upstream of the manifold  316 . In particular, the electronic control valves and pressure sensors  223  are located along the leak-off conduits  322 , between the nozzles  320  and manifold  316 . As discussed in detail below, the presence of the electronic control valve and pressure sensor  323  allows the pressure in each line  318  to be dynamically and selectively controlled and set for any desired stabilization pressure values, including values in excess or different than 4000 psi. In particular, it allows the pressure at each nozzle  320  to be controlled independently with respect to the pressures at the other nozzles  320 . 
     The control valve and pressure sensor assembly  323  is best shown in  FIG. 10 . The control valve may be any type of control valve or pressure relief valve known in the art, such as a solenoid and the like, and serves to vacate pressurized fuel from each nozzle  320  to the manifold  316 , when necessary. As shown therein, each control valve assembly  323  is in electrical communication with an engine control unit  325 , which is, in turn, in electrical communication with the engine and receives input from the engine. As will be readily appreciated, the engine control unit determines the amount of fuel, ignition timing and other parameters of the internal combustion engine needed to keep the engine running smoothly. It does this by reading and interpreting input values from the engine, e.g., engine speed, calculated from signals coming from sensor devices monitoring the engine. These input values from the sensor devices in the engine are fed to the engine control unit  325 , which then analyzes this information. The pressure sensors of the control valve assemblies  323  also feed information, in the form of the pressure detected at each nozzle  320 , to the engine control unit  325  for reading and processing. 
     In operation, the engine control unit  325  sends a signal to one or more of the control valve assemblies  323  to open or close the control valves in dependence upon the particular operating parameters of the engine, as detected by the sensor devices, and in dependence upon the pressure readings obtained by the pressure sensors of the control valve assemblies  323 . In this respect, the control valve assemblies  323 , in combination with the engine control unit  225 , are capable of dynamically and selectively controlling the pressures within each of the nozzles  320 . 
     As will be readily appreciated, the control valve assemblies  323  allow for the reduction of build-up of pressure in each nozzle  320 , e.g., during a starting operation, and can also be selectively actuated in order to lower the opening and closing pressure of each nozzle during low idle to reduce idling noise and the like, or at other times as necessary and in dependence upon readings from the sensor devices. In addition, the control valve assemblies  323  also allow for the build-up of pressure in each nozzle, by maintaining the control valve assemblies  323  in a closed condition, if necessary. 
     Importantly, the addition of a control valve assembly  323  to each nozzle  320  along each leak-off conduit  322  allows the pressure at each nozzle  320  and injection conduit  318  to be more precisely controlled, further reducing emissions. In particular, the injection apparatus  300  ensures that each individual fuel stream provided to the combustion chamber is maintained at a precise elevated pressure, especially at the nozzles  320 , thereby ensuring a more complete combustion of these fuel streams and an associated reduction in exhausted polluting contaminants. In addition, the pressure range and duration at each nozzle  320  may also be controlled with the addition of the control valve assembly/pressure sensor device  323 . 
     While  FIG. 8  illustrates a control valve and pressure sensor  323  for each leak-off conduit  322 , it is contemplated that any number, for example less than all, of the leak-off conduits  322  can be configured with a control valve and pressure sensor, without departing from the broader aspects of the present invention. Indeed, the controlled hydraulic nozzle injection apparatus  300  includes as many as one control valve  323  for each leak-off conduit  322 , and the exact number of such devices may be determined by the starting requirements of a particular engine. 
     In operation of the injection apparatus  300 , the fuel pump pressurizes a predetermined amount of fuel from an unillustrated fuel supply. As best shown in  FIG. 9 , once the pressurized fuel overcomes the biasing force of a check spring  232 , a check ball valve will be displaced, thereby allowing the pressurized stream of fuel to pass through the injection conduits  318  on the way to the nozzles  320  where a needle valve, or the like, opens and releases an atomized fuel stream into the combustion chamber of a motorized vehicle. 
     At the end of the initial fuel delivery cycle, the check ball valve  234  will resume its blocking position leaving a measured amount of residual fuel, and therefore pressure, trapped in the injection conduits  318 . As with the apparatus  200  of  FIG. 6 , while known systems remove this residual pressure, the present invention arrests the remaining pressurized fuel by virtue of the pressure relief valve assembly  230 . Further operation of the apparatus  300 , in some embodiments, follows the operation of the apparatus  200  described above in connection with  FIG. 6 . In any event, however, the addition of a pressure control valve  323  for each fuel injection nozzle  322  and each injection conduit  318  allows the pressure of fuel within each conduit  318  and at each nozzle  322  to be precisely controlled at almost any point in the fuel delivery process. In particular, the pressure within each conduit and at each nozzle  322  can be dynamically and selectively controlled, and can be controlled independent of the other nozzles  322  and conduits  318 , in dependence upon readings from the associated pressure sensor and input information from the engine regarding engine operating parameters and conditions. As will be readily appreciated, this added level of control further reduces undesirable emissions and provides for more complete combustion of atomized fuel. 
     As discussed above,  FIG. 3  shows the injection lines of a conventional fuel injection pump  112  connected to a manifold having a plurality of valve sets  125  which are utilized to control the flow and pressure of the fuel streams provided by the fuel pump  112 .  FIG. 4  is an enlarged, partial cross-sectional view of the valve sets  125  utilized to control the flow and pressure of the fuel streams in accordance with the present invention. Referring now to  FIG. 11 , a controlled nozzle injection apparatus  400  according to another embodiment of the present invention is shown, in which piston and ball valves are utilized to control the flow of fuel, as discussed hereinafter. 
     As shown in  FIG. 11 , a fuel injection pump  402  having a pumping plunger  404  is provided to intermittently supply the injection apparatus  400  with a pressurized stream of fuel. As discussed above, the fuel is typically a hydrocarbon fuel comprising gasoline, diesel fuel or the like. The pump  402  operations to send streams of pressurized fuel through, in succession, a valve assembly  406 , a fuel injection conduit  408  or conduits and, finally, to a fuel injector nozzle  410 , or a plurality thereof, which exhaust the fuel streams into an unillustrated combustion chamber of a vehicle. A fuel return conduit  412  is also provided for depressurizing the high pressure injection conduit  408 . 
     As with the embodiments discussed above, each of the nozzles  410  typically include a known arrangement of needle valves or the like which, when subjected to a threshold pressure, will permit passage of the pressurized fuel into the combustion chamber. The nozzles  410  do not, however, include leak off valves, conduits or the like which are typically provided to known nozzle assemblies to evacuate residual fuel therefrom (as discussed previously). The present embodiment utilizes such leakless nozzles in order to trap residual, pressurized fuel within an unillustrated spring chamber of the needle valves for subsequent use. Moreover, although there are a discreet number of conduits and fuel injector nozzles shown in  FIG. 11 , it will be readily appreciated that the present invention contemplates the incorporation of any number of conduits or nozzles without departing from the broader aspects of the present invention. 
     As further shown in  FIG. 11 , the valve assembly  406  is provided with a plurality of differing valve sets which are utilized to control the flow and pressure of the fuel streams provided by the fuel pump  402 .  FIG. 11  is an enlarged, partial cross-sectional view of the valve assembly utilized to control the flow and pressure of the fuel streams in accordance with the present invention. 
     As shown in  FIG. 11 , a spring-biased ball  414  works in concert with a piston  416  and ball  418  to bootstrap residual pressure left in the injection apparatus  400  at the conclusion of each fuel cycle. By doing so, the present invention maintains high fuel injection pressures at the end of the fuel delivery cycle, similar to the high injection pressures present at the beginning of the fuel delivery cycle. 
     Operation of the injection apparatus  400  will now be described in conjunction with  FIG. 11 . By way of example, if a 3000 psi residual pressure is desired, then fuel is supplied by the pump  402  and the residual pressure control valve  401  would be set for 3000 psi. If operation is picked up during injection, the pressure in the injection line  408  is approximately 12,000-15,000 psi and the nozzle is open and flowing fuel. Some fuel may leak past the nozzle valve of the nozzle  410  and into the nozzle spring chamber. The spring chamber of the nozzle(s)  410  is sealed (leakless nozzle) so that leakage will increase the spring chamber pressure. In between injections, the residual line pressure is 3000 psi and some fuel will leak out of the spring chamber into the nozzle end of the injection line  408 . As a result, the spring chamber pressure will be equal to the average line pressure, typically 90% of the residual pressure plus 10% of the peak line pressure, in this example 3500 psi. In an embodiment, for starting, the residual pressure control valve  401  may be set for zero pressure in which case the nozzle opening pressure will be static nozzle opening pressure produced by the nozzle valve spring. 
     In between injections, spring biased ball  414  is pressed against its seat  420  by its spring  422  and by the 3000 residual pressure in the line. Similarly, piston  416  is pressed against its minimum travel stop  424 . At the start of the next pumping event, piston  416  will be forced upward, holding ball  418  tightly against its seat  426  and preventing any backflow into the residual pressure circuit, i.e., return conduit  412 . Ball  414  will be lifted off its seat  420 , against the spring bias, and fuel will flow towards the nozzle  410 . Pressure will build up in the nozzle  410  until it gets high enough to lift the nozzle valve. The nozzle valve is held closed by the spring force and by the spring chamber pressure acting on the nozzle valve. The pressure required to overcome the spring force is the static nozzle opening pressure (in this case somewhere around 2500 psi). The pressure required to overcome the spring chamber pressure depends on the nozzle geometry, however, it is typically 1.5 times the spring chamber pressure (in this case, approximately 5250 psi). This makes the net nozzle opening pressure 7750 psi, which cannot be easily obtained by spring force alone. 
     As will be readily appreciated, this high operating pressure is particularly advantageous when the nozzle valve is to be closed. In a conventional nozzle, it takes approximately 2500 psi acting on the net area (A 1 -A 2 ) to develop enough force to overcome the spring force and begin to open the valve. As soon as the nozzle lifts off its seat, fuel flows into the nozzle sac (area A 2 ). With pressure acting over the full area A 1  (as opposed to the net area (A 1 -A 2 ), the nozzle valve snaps open. At closing, the pressure must drop well below the static opening pressure before the net force (i.e. the pressure acting over the full area A 1 ) drops below the spring force. Dynamically, in a conventional nozzle, the nozzle pressure must drop much further, perhaps below 1500 psi, before there is enough force imbalance to accelerate the nozzle valve in the closing direction. At such time, the engine cylinder pressure is high and the net pressure drop across the nozzle orifices will be small. As a result, fuel may dribble out of the nozzle at the end of injection, and there is even a danger that combustion gases could be forced through the nozzle holes into the nozzle. 
     With the apparatus  400  of the present invention, however, the spring chamber pressure plus the spring force combine to force the nozzle valve closed. The nozzle valve acts as a pump and forces the last bit of fuel out of the nozzle  410  and maintaining good atomization right until the very end of injection. 
     With further reference to  FIG. 11 , to complete the cycle, the pumping plunger spill ports (not shown) are opened, thus dropping the pumping chamber pressure. Ball  414  is forced against its seat  420  by its spring  422  and by the pressure in the injection line  408 . Importantly, ball  414  acts very much like a zero retraction delivery valve, trapping excess fuel in the line  408 . Low pressure in the pumping chamber also allows piston  416  to move downward into contact with its minimum travel stop  424  such that ball  418  is no longer forced against it seat  426 . A passageway is thereby created such that excess pressure in the line  408  can then flow past ball  418 , bringing the line pressure down to the level of the residual pressure gallery  428 . During every injection, a small quantity of fuel enters the residual pressure gallery  418 , so a simple control valve may be utilized to bleed off the excess to maintain the desired residual gallery pressure (in this case approximately 3000 psi). 
     For example, as shown in  FIG. 4 , a simple spring loaded ball to control the residual pressure and a solenoid operated shuttle valve to turn the residual pressure control on and off may be utilized. Moreover, any number of mechanical and/or electrical systems can be utilized to control the residual pressure with whatever degree of sophistication is required. 
     In the embodiment shown in  FIG. 11 , valves  414  and  418  are shown as balls acting on a conical seat, however, conical valves acting against conical seats may be utilized without departing from the broader aspects of the present invention to achieve even more reliable operation (i.e., conical valves may be more durable and reliable). 
     As discussed above, the controlled hydraulic nozzle injection system  400  of the present invention allows a user to change nozzle opening and closing pressure while the engine is running. As also discussed above, there are two main parts to the system  400 . The first part are control valves which may be installed in the injection lines between the pump and the nozzles, as shown in  FIG. 12 , or they may be built into the fuel injection pump, as discussed above in connection with  FIG. 11 . The second part of the system is a set of leakless nozzles. In an embodiment, the leakless nozzles may be conventional nozzles with the leakoff line sealed. 
     As shown in  FIG. 12 , in an embodiment where the control valves are installed in the injection lines, the assembly shown in box A may be grafted to the top of the pumping chamber. As shown therein, the components shown therein are substantially similar in arrangement to the valve assembly  406  shown in  FIG. 11 . In particular, the assembly in box A includes an injection line fitting  450  from the pumping chamber and an injection line fitting  452  to the nozzle inlet. The assembly includes a residual pressure valve  454  for controlling the pressure from a control pressure manifold via conduit  456  and a forward check valve  458  similar to ball valve  414 . 
     While the invention had been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various obvious changes may be made, and equivalents may be substituted for elements thereof, without departing from the essential scope of the present invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention includes all embodiments falling within the scope of the appended claims.