Patent Publication Number: US-2010108786-A1

Title: Fuel injector assembly

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention generally relates to a fuel injector and to an optimized geometry of a clevis, and, more particularly, to a clevis having an optimized geometry for substantially eliminating side loading effects on a plunger during operation of the fuel injector, thereby maintaining fuel injector performance integrity. 
     2. Background Description 
     There are many types of fuel injectors designed to inject fuel into a combustion chamber of an engine. For example, fuel injectors may be mechanically, electrically or hydraulically controlled in order to inject fuel into the combustion chamber of the engine. In the hydraulically actuated systems, a control valve body may be provided with two, three or four way valve systems, each having grooves or orifices which allow fluid communication between working ports, high pressure ports, and venting ports of the control valve body of the fuel injector and the inlet area. The working fluid is typically engine oil or another type of suitable hydraulic fluid capable of providing pressure within the fuel injector in order to begin the process of injecting fuel into the combustion chamber. 
     In current designs, a driver will deliver a current or voltage to the open side of an open coil solenoid. The magnetic force generated in the open coil solenoid will shift a spool into the open position so as to align grooves or orifices (hereinafter referred to as “grooves”) of the control valve body and the spool. The alignment of the grooves permits the working fluid to flow into an intensifier chamber from an inlet portion of the control valve body (via working ports). The high-pressure working fluid then acts on an intensifier piston which pushes the plunger to compress fuel located within a high pressure fuel chamber. As the pressure in the high pressure fuel chamber increases, the fuel pressure will begin to rise above the needle check valve opening pressure. At the prescribed fuel pressure level, the needle check valve will lift against the needle spring and open the injection holes in a nozzle tip. The fuel will then be injected into the combustion chamber of the engine. The above process describes an injection event. 
     After an injection event, the driver will deliver a current or voltage to a closed side of the coil solenoid. The magnetic force generated in the closed coil solenoid will then shift the spool into a closed position, so as to align the grooves or orifices of the control valve body and the spool with a reservoir. At this time, the intensifier spring will force the plunger and piston upwards toward the working port to evacuate the working oil within the intensifier chamber to the reservoir via the working ports and aligned grooves. As the plunger moves upward, fuel is provided to the high pressure fuel chamber. This cycle is referred to as the return or fill stroke. After the high pressure fuel chamber is completely filled and the piston and plunger are stopped, the parts remain in this state until the next injection event. This cycle is referred to as a dwell time between injection events. 
     In the related art, as represented in  FIG. 1 , the loading force generated from the spring force is transferred to the plunger head  112 A during the dwell time, return and injection event. This can cause side loading effects resulting in wear and scuffing of the plunger which, in turn, decreases the performance of the fuel injector. More specifically,  FIG. 1  shows a piston  102  positionable within an intensifier chamber  100  and movable between a first position and a second position as indicated by arrow  104 . A plunger head  112 A is positionable within a receiving portion  114  of a clevis  110 , and a spring  116  is positionable about the body portion  112 B of the plunger  112  and an outer circumference of the clevis  110 . The clevis  110  includes a shoulder  118  and a lip portion  120 . 
     In the related art, the plunger head  112 A is held tightly between the lip portion  120  of the clevis  110  and the piston  102 , with no clearance. In this manner, during operation the spring force will act on the shoulder  118  of the clevis  110  where such force will be transferred to the lip  120  of the clevis  110 . This spring force will then act on the plunger and create a side loading effect on the plunger  112  that results, over time, in removal or scuffing of a film on the plunger (e.g., 0 to 2 μm of film deterioration) and/or wear on the metal surfaces of both the plunger and wall of the intensifier chamber (e.g., up to 50 μm or more of wear). This is due to uneven spring forces generated on the shoulder  118  of the clevis  110 . In the related art scuffing and/or wearing is caused by interaction between the spring  116  and the clevis  110  and results in an increased clearance or gap between the plunger  112  and the intensifier chamber wall. This results in pressure loss within the intensifier chamber; mixing of the fuel with oil, since fuel will be able to leak into a spring cavity and eventually into the cylinder head; loss of sealing capabilities; and an overall loss of injector performance. This ultimately leads to degradation of injector performance. 
       FIG. 2  shows a graphical representation of the fuel leak rate (cc/S) versus plunger clearance (μm) in a related art system. The curve represents experimental data collected from a related art injector collected over a predetermined testing period. These actual or observed results are far worse than the theoretical results calculated by the following equation. That is, in the related art fuel injectors a much higher fuel leak rate should be expected than predicted theory. More specifically, the equation below predicts results below the experimental data curve as shown in  FIG. 2 . 
     
       
         
           
             Q 
             = 
             
               
                 π 
                 12 
               
                
               
                 
                   D 
                   · 
                   
                     C 
                     3 
                   
                 
                 
                   L 
                   · 
                   ρ 
                   · 
                   v 
                 
               
                
               P 
             
           
         
       
     
     In this equation, D is diameter of the plunger, C is the radial clearance, L is the length of the plunger (flow path) in sealing region, ρ is the density of the fluid, ν is the kinematic viscosity of the fluid, and P is the pressure. Comparing the experimental results to the theoretical results, it can be determined that the experimental results are far worse than predicted. For example, at a plunger clearance of 30 μm the equation indicates a fuel leak rate of approximately a 0.5 cc/s, whereas experiments demonstrate an actual fuel leak rate of approximately 2.8 cc/s. Accordingly, there is a need for an improved injector that minimizes or eliminates the disadvantages of the related art. 
     The invention is directed towards overcoming one or more of the problems and disadvantages of the related art. 
     SUMMARY OF THE INVENTION 
     In an aspect of the invention an apparatus is provided that substantially eliminates side loading effects on a plunger. For example, a clevis is provided having a geometry which substantially eliminates side loading effects on a plunger during operation. In another aspect of the invention a device comprises a clevis having a geometry that substantially eliminates frictionally induced deterioration on a body portion of a plunger. 
     In a further aspect of the invention, an injector structure comprises a piston, a plunger including a first portion and a second portion, and a clevis. The clevis comprises a structure in communication with a first portion of the plunger, wherein the clevis structure substantially eliminates side loading effects generated from a spring force being transferred to the plunger during operation. 
     In another aspect of the invention, a fuel injector comprises a body control valve having an inlet port and working ports. At least one solenoid coil is positioned at an end or ends of the body control valve and an intensifier chamber. Alternatively, a solenoid and/or spring can provide the desired opposing forces. The intensifier chamber comprises a piston, a plunger having a first portion and a second portion, a spring positionable substantially about the second portion of the plunger, and a clevis having a receiving portion. Further, the receiving portion has a profile which allows the plunger to free float therein. A contacting portion moves the piston from a first position to a second position during a return time between injection events via a spring loading force exerted on the loading portion of the clevis. A high pressure fuel chamber is arranged below the second portion of the plunger and a needle chamber having a needle responsive to an increased fuel pressure created in the high pressure fuel chamber. 
     In yet another aspect of the invention, a device comprises a means for substantially eliminating side loading effects on a plunger during operation and a biasing means contacting the eliminating means. The biasing means moves a piston from a first position to a second position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a cross-sectional view of a portion of a fuel injector during a dwell time between injection events according to the related art; 
         FIG. 2  shows a graph illustrating data according to the related art; 
         FIG. 3A  shows a perspective view of a clevis according to an embodiment of the invention; 
         FIG. 3B  shows a cross-sectional view of  FIG. 3A  along line A to A′ with a plunger; 
         FIG. 3C  shows a top down view of  FIG. 3A  with a plunger; 
         FIG. 3D  shows a cross-sectional view of a clevis and plunger and piston assembly according to another embodiment of the invention; 
         FIG. 3E  shows a cross-sectional view of a clevis and plunger and piston assembly according to another embodiment of the invention; 
         FIG. 4A  shows a perspective view of a clevis according to another embodiment of the invention; 
         FIG. 4B  shows a cross-sectional view of  FIG. 4A  along line B-B′; 
         FIG. 5A  shows a perspective view of a clevis according to another embodiment of the invention; 
         FIG. 5B  shows a cross-sectional view of  FIG. 5A  along line B to B′ with a plunger and piston assembly; 
         FIG. 6  shows a cross-sectional view of a portion of a fuel injector during a dwell time between injection events according to the invention; 
         FIG. 7  shows a graph illustrating data according to the invention; and 
         FIG. 8  shows a cross-sectional view of a fuel injector assembly according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
     The invention is directed to an oil-activated electronically, mechanically or hydraulically controlled fuel injector, including a clevis having an optimized geometry for maintaining the performance integrity of the fuel injector. This geometry substantially prevents or eliminates scuffing of a film on a plunger, as well as metal-to-metal (or alloy) wear on the plunger and intensifier chamber. The substantial prevention or elimination of scuffing and/or wearing reduces or prevents fuel leaking and maintains performance integrity of the fuel injector. This is accomplished by allowing the plunger to “free float” within the clevis; that is, an optimized geometry of the clevis of the invention substantially eliminates side loading effects on the plunger, thereby maintaining performance integrity of the fuel injector. 
     Embodiments of the Oil-Activated Fuel Injector of the Invention 
       FIG. 3A  shows a perspective view of a clevis according to an embodiment of the invention. Referring to  FIG. 3A , a clevis is generally depicted as reference numeral  300 . The clevis  300  includes a shoulder portion  302  having a contacting portion or surface  304  for contacting a piston (not shown) and a loading portion  306  for receiving spring forces. A receiving portion  308  is capable of receiving a portion of the plunger (not shown). The clevis  300  further includes an optional lip portion  310  including an upper surface  322  for contacting a portion of the plunger (not shown) during a low or no fuel condition. The clevis includes an optimized geometry, which is a profile or height measured by the distance between the upper surface  312  and the shoulder  304 , in embodiments. 
       FIG. 3B  shows a cross-sectional view of  FIG. 3A  along line A to A′. Referring to  FIG. 3B , the clevis  300  includes the shoulder  302  having a contacting portion  304  for contacting a piston portion (not shown) and a loading portion  306  for receiving a spring (not shown). The clevis has a height A measured from an inside surface of the clevis, an inner circumference C, and an outer circumference B. The height A is set to be greater than a height of the plunger head A′, thereby leaving a distance D in the receiving portion  308 . The distance D can range from about 0 mm or higher, for example, in a range from about 0.5 mm to 1.0 mm or higher. The distance is set to substantially eliminate side loading effects on the plunger during operation of the injection by preventing the spring force from acting on the plunger. In other words, the distance D allows for the plunger to be “free floating.” 
     Additionally, as shown in  FIG. 3B , the plunger  310  includes a body portion  312 , a neck portion  314 , and a head portion  316  (plunger head). The neck portion  314  may have a smaller diameter than the remainder of the plunger head  316  and the body portion  312 , thereby allowing the neck portion  314  to pass through the opening  318  or slit of the clevis, and more particularly, allowing the plunger head  316  to be arranged within the receiving portion  308  of the clevis  300 . Optionally, the plunger  310  may have a substantially uniform diameter if desired, depending on the geometry of an optional lip  320  portion of the clevis  300 . The lip portion includes an upper surface  322  or contact portion capable of supporting a lower portion of the plunger head  316  during low fuel or no fuel conditions. 
     The plunger head  316  is arranged between the sidewalls of the clevis  300 . For example, the plunger head  316  is arranged inside the inner circumference portion of the clevis  300 . A portion of the spring (not shown) is arranged along an outer circumference of the clevis and in contact with the loading portion  306  of the shoulder  302 . It should be understood that the clevis may take on any geometry in order to substantially eliminate side loading effects of a plunger assembly during operation and, in one aspect, a non-injection event. 
       FIG. 3C  shows a top down view of  FIG. 3B . As shown, the clevis  300  has a shoulder  302  with a contacting surface  322 | for contacting the plunger, a top portion of the plunger head  316 , and a receiving portion  308  for receiving the plunger head  316 . The opening  318  or slit allows the plunger neck  314  to be inserted into the receiving portion  308 , thereby the plunger head  316  can be arranged inside the receiving portion  308 . 
       FIG. 3D  shows a cross-sectional view of the clevis according to another embodiment of the invention. In this embodiment, the clevis  300  includes a shoulder  302  having a top contacting surface  304  which contacts a portion of the piston  350 . The clevis further includes a loading portion  306  for receiving a spring. The clevis has a height A″ measured from an inside surface|  322  of the clevis to the top contacting surface  304 . In this embodiment, the height A″ is less than a height of the plunger head A′″; however, due to the offset space  355  of the plunger a distance D′ remains between an upper surface of the piston  350  and an upper surface of the plunger head  316 . The distance D′ may range from about 0 mm or higher, for example, in a range from about 0.5 mm to 1.0 mm or more, and is set to substantially eliminate side loading effects on the plunger during operation of the injection. This is accomplished by preventing the spring force from acting on the plunger itself (e.g., the distance D′ allows for the plunger to be “free floating”). The offset space may be designed in any geometry to allow the plunger to be “free floating.” 
       FIG. 3E  shows a cross-sectional view of clevis according to another embodiment. In this embodiment, a protruding portion “P” of the piston is designed to sit within a portion of the clevis. The clevis  300  includes a shoulder  302  having the top contacting surface  304  that contacts the piston portion and a loading portion  306  for receiving a spring. In this embodiment, the clevis has a height A′″ measured from an inside surface of the clevis  300  to the top contacting surface  304 . The height A′″ is set to be greater than a height of the plunger head A″″, thereby leaving a distance D″ in the receiving portion  308 . The distance D″ can range from about 0 mm or higher, for example, in a range from about 0.5 mm to 1.0 mm or more and is set to a length that substantially eliminates side loading effects on the plunger during operation of the injection. This is accomplished by preventing the spring force from acting on the plunger itself. However, in this embodiment the height A′″ will be greater than the combination of the protruding portion and the plunger head to provide the amount offset space to allow the plunger to be “free floating.” 
       FIG. 4A  shows a perspective view of a clevis according to another embodiment of the invention. Referring to  FIG. 4A , the clevis of this embodiment is generally depicted as reference numeral  400 . The clevis  400  includes a shoulder portion  402  having a contacting portion  404  for contacting a piston and a loading portion  406  for receiving spring forces. A receiving portion  408  is formed in an inner portion of the clevis  400  and receives a portion of the plunger (not shown). 
       FIG. 4B  shows a cross-sectional view of  FIG. 4A  along line B to B′ according to another embodiment of the invention. In this view it is seen that the shoulder portion  402  includes the contacting portion  404  for contacting a piston (not shown) and the loading portion  406  for accepting the spring force of a spring. The clevis has a height H measured from an inside surface of the clevis to an upper surface, an inner circumference F, and an outer circumference G. The height H is set to be greater than the plunger head  410  when the plunger  412  is arranged inside the receiving portion  408  of the clevis  400 , thereby leaving a distance E measured from a top portion of the plunger head  410  to a top surface of a contacting portion  404  of clevis  400 . The distance E may be in a range from about 0 mm or higher, for example, in a range from about 0.5 mm to 1.0 mm or higher. The distance is set to substantially eliminate side loading effects of a plunger assembly during operation of the fuel injector. It should be understood that the clevis may take on any geometry in order to substantially eliminate side loading effects of a plunger assembly during operation and, in one aspect, a non-injection event. 
     In this configuration there is no slit or opening as in the previous embodiments. As a result, the plunger  408  may have a substantially uniform diameter throughout. The plunger head  410  is arranged in the receiving portion  408  of the clevis  400  by inserting the plunger through the receiving portion  408 . Accordingly, the plunger is configured to have a smaller diameter than the inner circumference F of the clevis  400  to allow for movement of the plunger. Optionally, the diameter of the plunger does not have to be substantially uniform. For example, the plunger  408  may have a neck portion as previously described in foregoing embodiments. 
       FIG. 5A  shows a perspective view of a clevis according to an embodiment of the invention. Referring to  FIG. 5A , the clevis is generally depicted as reference numeral  500  and includes a shoulder portion  502  having a contacting surface  504  for contacting a piston (not shown), and a loading portion  506  for receiving spring forces. In this embodiment, the clevis  500  has a ring shape with a slit or opening  518 . A receiving portion  508  is designed to receive a portion of the plunger. The opening or slit  518  allows the plunger neck  514  to be inserted therethrough into the receiving portion  508 . The contacting surface  504  may contact a portion of the plunger (not shown) in low or no fuel conditions. Optionally, a portion of the inner circumference of the ring may be beveled. 
       FIG. 5B  shows a cross-sectional view of  FIG. 5A  along line B to B′ with a plunger and piston assembly. The top contacting surface  504  of the clevis contacts a portion  550  of the piston. The loading portion  506  receives the spring, and the opening  518  allows the plunger neck  514  to be inserted therethrough into the receiving portion  508 . The piston  525  is designed to have an offset portion  555  over at least a portion of the plunger head  516 . In this embodiment, the plunger head  516  is arranged inside the offset portion  555  of the piston  525 |. The offset portion  555  is set to a distance that is larger than the height of the plunger head  516 . Also, the offset portion  555  is designed to allow for the plunger to be “free floating” by having the spring force applied only to the surface  506 . 
       FIG. 6  shows a cross-sectional view of a portion of a fuel injector during a dwell time between injection events in accordance with the invention. In  FIG. 6 , the intensifier chamber is generally depicted as reference  600 . A piston  602  is positionable within the intensifier chamber  600  and is movable between a first position and a second position as indicated by arrow  604 . As represented in  FIG. 6 , immediately prior to an injection event the piston  602  is positioned proximate to a control valve assembly  606 . 
     Still referring to  FIG. 6 , the intensifier chamber  600  further houses the clevis of the invention and a plunger  612 . The plunger  612  includes a plunger head  612 A, a plunger body  612 B, and a plunger neck  612 C. The plunger head  612 A is positionable within a receiving portion  614  of the clevis  603 |. A spring  616  is provided within the intensifier chamber  600 , and, more particularly, is positionable about the body portion  612 B of the plunger  612  and an outer circumference of the clevis  603 . In one aspect of the invention, the spring  616  is positioned within an inner bore of the piston  602 . 
     The clevis  603  may include a shoulder portion  602  with loading portion  606  for receiving spring forces and a contact portion  605  for contacting a piston  602 . A receiving portion  614  is capable of receiving a portion of the plunger head  612 A. The clevis  603  further includes an optional lip portion  610  including an upper surface  612  for contacting a portion of a plunger during a low or no fuel condition. The clevis  603  includes an optimized geometry having a profile or height measured by the distance between the upper surface  612  and the upper surface of the contact portion  605 . 
     In implementation, the profile of the clevis (e.g., the substantially vertical wall between the shoulder and lip portion) is greater than a head portion  612 A of the plunger  612 . In this manner, the plunger  612  is free floating within the intensifier chamber  600 , and more particularly, within the receiving portion  614  of the clevis. As discussed in detail, the profile of the clevis in relation to the head portion  612 A of the plunger  612  substantially eliminates or prevents wear and/or scuffing of the plunger body  612 B, as well as wear and/or scuffing on the wall of the intensifier chamber during a dwell time between injection events and during an injection event. 
     Optionally, as discussed, the clevis  603  may have an opening or slit portion  609  for receiving a head portion  612 A of the plunger, and a neck portion  612 C of the plunger  612 . In this configuration, the neck portion  612 C has a smaller diameter than the rest the plunger  612  and the opening  609 . The neck portion  612 C is inserted into the opening or slit portion  609  allowing the plunger head  612 A to be arranged within the receiving portion  614  of the clevis  603 . 
     Alternatively, the head portion  612 A, neck portion  612 C, and body portion  612 B of the plunger  612  may have substantially the same diameter, as described with reference to  FIGS. 4A-4C . The diameter of the plunger may depend on whether a lip is utilized. For example, if no lip is provided the plunger may have a substantially uniform diameter allowing the head portion  612 A to be positionable within the clevis. It should be understood that the geometry and the piston as described in any of the embodiments may be mixed and matched to form the fuel injector assembly. For example, the piston with the offset portion may be utilized with any of the clevis geometries described herein. 
     Additionally, the invention may be a replacement kit for a fuel injector assembly. For example, a replacement kit includes the clevis having an optimized geometry for substantially eliminating side loading effects on a plunger. The kit may include a replacement plunger configured to operate with the replacement clevis and original injector. That is, by using the replacement kit on a used injector, it can be modified to ensure that there is substantially no deterioration in performance after a period of use of operation (e.g., injection events). Optionally, boring and/or resurfacing the intensifier chamber may be utilized to ensure proper tolerances between the plunger and the intensifier chamber. Additionally, the boring will substantially eliminate any damage which may have occurred to the intensifier chamber. 
       FIG. 7  shows a graph illustrating data according to the invention.  FIG. 7  graphs coating wear (μm) versus test duration (hours). This graph shows a conventional fuel injector as curve  702  and a fuel injector according to the invention as curve  704 . The injector according to aspects of the present invention has substantially less scuffing and/or wearing over time than that of a conventional injector. Accordingly, the injector of the invention has superior performance over time as compared to the conventional injector. As previously discussed and illustrated in this graph, the conventional injector has side loading effects causing scuffing and/or wearing because of interaction between the spring and the clevis. This results in an increased clearance or gap between the plunger and the intensifier chamber wail. This in turn results in pressure loss within the intensifier chamber, mixing of the fuel with oil due to allowing fuel to leak into a spring cavity and eventually into the cylinder head, loss of sealing capabilities, and ultimately overall loss of injector performance. As shown by this graph, the invention overcomes one or more of the problems and disadvantages as set forth above by substantially eliminating scuffing and/or wear. 
     Operation of the Oil Activated Fuel Injector of the Invention 
       FIG. 8  shows an overall view of the fuel injector assembly  800 . The intensifier body  820  is mounted to a valve control body  801  via any conventional mounting mechanism. A piston  822  is slidably positioned within the intensifier body  820  and is in contact with an upper end of a plunger  824 . An intensifier spring  826  surrounds a portion (e.g., shaft) of the plunger  824  and is further positioned between the clevis  803  and a flange or shoulder formed on an interior portion of the intensifier body  820 . The intensifier spring  826  urges the piston  822  and the plunger  824  in a first position proximate to the valve control body  801 . In general, a high-pressure chamber  830  is formed by an end portion  825  of the plunger  824  and an interior wall  827  of the intensifier body  820 . A fill path  833  provides fuel into the high-pressure chamber  830  via a fuel inlet  832 . 
     The nozzle generally depicted as reference numeral  840  is in fluid communication with the high-pressure chamber  830  via a fuel bore  834 . It should be recognized that the fuel bore  834  may be straight or angled or at other known configurations. Upon fuel compression into the high-pressure chamber  830 , fuel flows from the high-pressure chamber  830  to the nozzle  840 . A spring cage  842  (which may be a separate component from the nozzle  840 )|, which typically includes a centrally located bore, is bored into the nozzle  840 . A spring  844  and a spring seat  846 | are positioned within the centrally located bore of the spring cage  842 . The nozzle  840  further includes a discharge path  848  in alignment with the fuel bore  834 . A needle  850  is preferably centrally located with the nozzle  840  and is urged downwards by the spring  844 . A fuel chamber  852  surrounds the needle  850  and is in fluid communication with the discharge path  848 . 
     In operation, a driver (not shown) will first energize the coil and in this position the working fluid pressure within the pressure chamber  830  should be much lower than the rail inlet pressure. The energized coil will then shift the spool  810  to an open position. In one embodiment, a coil and opposing spring can provide forces to move the spool. In the open position, the groove  812  will overlap with the bore and the cross bore (not shown in detail.) This will allow the working fluid to flow between the inlet port  802  and the intensifier chamber via the working port  806 , and simultaneously seal the vent port. 
     During an injection event the pressurized working fluid is allowed to flow into the working port  806  where it begins to act on the piston and the plunger. That is, the pressurized working fluid will begin to push the piston and the plunger downwards, compressing the intensifier spring. As the piston is pushed downward, fuel in the high pressure fuel chamber will begin to be compressed via the end portion of the plunger. A quantity of compressed fuel will be forced through the bores into the heart chamber which surrounds the needle. As the pressure increases, the fuel pressure will rise above the needle check valve opening pressure until the needle and needle spring are urged upwards. At this stage, the injection holes in the nozzle are open allowing a main fuel quantity to be injected into the combustion chamber of the engine. During this event, the spring forces will act on the clevis, and not exert any a side loading force on the plunger|. 
     To end the injection event and start a non-injection event, the driver will energize the closed coil. The magnetic force generated in the coil will then shift the spool  810  into the closed position, which will offset the groove from the cross bore. This will open the vent port and allow fluid to flow from the intensifier chamber through the vent port. Also, the inlet port  802  will no longer be in fluid communication with the bore (and intensifier chamber). The working fluid within the intensifier chamber will then be vented to ambient pressure and the needle spring will urge the needle downward towards the injection holes of the nozzle thereby closing the injection holes. Similarly, the intensifier spring will exert a force on the clevis for urging the plunger and the piston into the closed or first position adjacent to the valve. 
     During this time, the plunger will move upward by forces in the high pressure chamber and fuel will again begin to flow into the high-pressure chamber of the intensifier body. Also, the spring forces will act on the clevis in order to move the piston from a first position to a second position. However, as discussed above, due to the geometry of the clevis and the clevis allowing the plunger to free float, no spring forces or loads will be transferred to the plunger, substantially eliminating side loading effects on the plunger during the non-injection event. This prevents or eliminates scuffing and wear of the plunger thus maintaining the performance integrity of the fuel injector. 
     While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims.