Abstract:
A clamping device for clamping a fuel injector to the cylinder head of an internal combustion engine, the fuel injector having a fuel injector body including a injector nozzle tip includes a hold down device for clamping to an object and a seal device for effecting a fluid seal with a plurality of fluid passageways defined in the cylinder head, the sealing device associated with each fluid passageway being compressible by a unidirectional force applied to the hold down device. A fuel injector for an internal combustion engine, the fuel injector having a fuel injector body including a injector nozzle tip includes a hold down device for clamping to an object and a seal device for effecting a fluid seal with a plurality of fluid passageways defined in the object, at least one seal device having a dimensional range in which an effective seal is made, the dimensional range being at least as great as the range of manufacturing tolerances existing is between the fuel injector and the object.

Description:
TECHNICAL FIELD 
     The present invention relates to a fuel injector for an internal combustion engine. More particularly, the present invention relates to apparatus for clamping and fluidly sealing the fuel injector to an object. 
     BACKGROUND OF THE INVENTION 
     A fuel injector must perform its prime function of delivering a desired fuel charge to an engine cylinder within a number of constraints. The first such constraint is a physical space constraint. The fuel injector must reside coincident with a plurality of valves and valve springs. With the need for increased efficiencies of internal combustion engines, the number of valves that service a cylinder has grown from the traditional two valves common only a few years ago to three, four, and even five valves. The fuel injection unit is forced to reside within the cluster of valves servicing the cylinder. 
     Another constraint within which the fuel injector must live is the need to provide adequate fluid sealing for a number of different passageways that must be coupled to the fuel injector. Due to manufacturing tolerances and the great fluid pressures involved, it has in the past proved difficult to consistently and effectively simultaneously seal the various fluid passageways that are coupled to the fuel injector. Additionally, present means for clamping the fuel injector to the engine cylinder head have imposed torque moments to the passageway seals, the torque moments contributing to seal leakage over time. 
     A fluid passageway that must be sealed is the passageway surrounding the injector tip where the tip projects into the combustion chamber. The pressure generated by ignition of the injected fuel is typically on the order of 2,500 pounds per square inch acting to leak around the fuel injector tip. 
     A number of current fuel injector designs employ a high pressure engine lubricating oil to actuate an intensifier plunger within the fuel injector to bring the pressure of the fuel at the time of injection up to approximately 20,000 pounds per square inch. The high pressure lubricating oil is delivered through a rail defined in the cylinder head to the fuel injector. The high pressure lubricating oil is typically at a pressure of approximately 3,500 pounds per square inch. The high pressure lubricating oil must be fluidly coupled from the rail to the fuel injector. This is a second fluid passageway that must be sealed. 
     There is a need in the industry to consistently clamp the fuel injector into place on the cylinder head. The clamping action must effect fluid seals at least at the injector tip and at the interface with the high pressure lubricating oil rail. Additionally, the means for clamping must be compatible with the limited space available in the cluster of valves servicing at the cylinder. Further, it would be a benefit to the industry for the clamping to minimize the effects of manufacturing tolerances on effecting the fluid seals and minimizing the torquing forces that the clamping action subjects the various fluid seals to. 
     SUMMARY OF THE INVENTION 
     The present invention substantially meets the aforementioned needs of the industry. The unit injector of the present invention includes devices for clamping the unit injector to the cylinder head that are compatible with the space limitations afforded by a number of different valve and valve spring arrangements. Additionally, the unit injector provides for fluid sealing of a plurality of orifices that minimize the effects of manufacturing tolerances in both the fuel injector and the cylinder head in which the fuel injector is installed. Further, torquing forces that could effect seals at the plurality of orifices are minimized. Further, a passageway is provided to convey high pressure lubricating oil from the rail defined in the cylinder head to the unit injector. 
     The present invention is a clamping device for clamping a fuel injector to the cylinder head of an internal combustion engine, the fuel injector having a fuel injector body including a injector nozzle tip. The clamping device includes a hold down device for clamping to an object and a sealing device for effecting a fluid seal with a plurality of fluid passageways defined in the cylinder head, the sealing device associated with each fluid passageway being compressible by a unidirectional force applied to the hold down device. Further the present invention is a fuel injector for an internal combustion engine, the fuel injector having a fuel injector body including an injector nozzle tip. The fuel injector includes a hold down device for clamping to an object and a sealing device for effecting a fluid seal with a plurality of fluid passageways defined in the object, at least one sealing device having a dimensional range in which an effective seal is made, the dimensional range being at least as great as the range of manufacturing tolerances existing between the fuel injector and the object. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional perspective view of the unit injector of the present invention; 
     FIG. 2 is a sectional side view of a crush barrel seal for sealing the connection with the high pressure lubricating oil rail; 
     FIG. 3 is an alternative preferred embodiment of the crush barrel seal for use at the junction with the high pressure lubricating oil rail; 
     FIG. 4 is a side sectional view of a crush barrel seal and employed to form a seal at the injector tip of the unit injector; 
     FIG. 5 is a top plan form view of a unit injector disposed between two valve springs, the high pressure lubricating oil passageway and seal being depicted in section; 
     FIG. 6 is a side sectional view of a jumper tube seal employed at the juncture with the high pressure lubricating oil rail; 
     FIG. 6 a  is a sectional view of an alternative means for sealing the jumper tube of FIG. 6; 
     FIG. 6 b  is a sectional view of an alternative means for sealing the jumper tube of FIG. 6; 
     FIG. 7 is a perspective sectional view of an alternative embodiment of the unit injector of the present invention; 
     FIG. 8 is a side elevational view of the injector tip of the unit injector having the sleeve and crush barrel seal depicted in section; 
     FIG. 9 is a perspective sectional view of a further preferred embodiment of the unit injector of the present invention; and 
     FIG. 9 a  is a side elevational view of the injector tip of the unit injector having the sleeve and washer seal depicted in section. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 depicts a plurality of engine components in relation to the unit injector of the present invention. The engine components include a cylinder head  10 . An injector receiver  12  is defined in the cylinder head  10 . The injector receiver  12  has a generally circular cross section that decreases in diameter in several stages as the depth of the injector receiver  12  increases into the cylinder head  10 . At the bottom of the injector receiver  12  an injector valve bore  14  extends between the injector receiver  12  and the combustion chamber (not shown). A portion of the combustion chamber wall  15  that defines the combustion chamber is depicted adjacent to the injector valve bore  14 . 
     A high pressure oil rail  16  is defined in the cylinder head  10 . The high pressure oil rail  16  terminates in an opening  17  at the surface of the cylinder head  10 . In the embodiment depicted in FIG. 9, a fuel rail  18  is additionally defined in the cylinder head  10  for providing a fuel supply to the unit injector. Returning to FIG. 1, a single valve spring  20  is depicted. Additional valve springs  20   a  and  20   b  as depicted in FIG. 5. A valve guide  24  is disposed within the cylinder head  10 . A valve guide  24  is paired with each of the valves in order to facilitate the translational motion of the valves between an opened and a closed disposition. 
     The unit injector of the present invention is shown generally at  30  in FIG.  1 . The unit injector  30  may be any of a number of different types of fuel injector units, but is preferably a component of a hydraulically-actuated electronically-controlled unit injector fuel system as presented in U.S. Pat. No. 5,191,867, incorporated herein by reference. 
     The unit injector  30  includes an actuator and valve assembly  32 , a body assembly  34 , a barrel assembly  36 , and a nozzle and tip assembly  38 . The nozzle and tip assembly  38  is disposed within a case  40 . The nozzle tip  42  projects through the injector valve bore  14  into the combustion chamber (not shown). A high pressure oil inlet  44  is defined in the body assembly  34  of the unit injector  30 . An oil drain  46  is defined in the body assembly  34  of the unit injector  30 . 
     The injector  30  further includes an injector retainer assembly  50  and a sleeve assembly  52 . The injector retainer assembly  50  of the unit injector  30  has a generally circular hold down dog  54  disposed peripheral to the body assembly  34  of the unit injector  30 . The dog  54  subtends a certain angle to underlie at least one valve spring. The hold down dog  54  has a bore  58  defined therein. The bore  58  is in registry with the valve guide  24  pressed into the cylinder head  10 . 
     A retainer wall  56  extends upward from the hold down dog  54 . The retainer wall embraces the outer surface of the body assembly  34  of the unit injector  30 . The retainer wall  56  has a relatively thin cross sectional area where the retainer wall  56  is adjacent to a valve spring  20 . The relatively thin cross sectional portions of the retainer wall  56  accommodate the minimal space defined between adjacent valve springs  20   a - 20   d  for the unit injector  30  to reside in. The retainer wall  56  may be formed integral with the body assembly  34  of the unit injector  30  or the retainer wall  56  may be formed separate and comprise a sleeve substantially encompassing the body assembly  34 . 
     A generally angled passageway support  60  extends between the hold down dog  54  and the retainer wall  56 . An oil passageway  62  is defined in the passageway support  60 . The oil passageway  62  is fluidly coupled at a first end to the high pressure oil rail  16  at the opening  17  thereof. The juncture of the oil passageway  62  and the high pressure oil rail  16  is sealed by an O-ring  64 . The oil passageway  62  is fluidly coupled to the high pressure oil inlet  44  at an opposed second end. The juncture of the oil passageway  62  and the high pressure oil inlet  44  is sealed by an O-ring  66 . The circular hold down dog  54  is maintained in compressive engagement with the surface of the cylinder head  10  by a bolt  68  threaded into a threaded bore defined in the cylinder head  10  and by portions of the hold down dog  54  underlying and being held in compressive engagement with the cylinder head  10  by the valve springs  20   a - 20   d.    
     The sleeve assembly  52  of the unit injector  30  is interposed between the case  40  of the nozzle and tip assembly  38  and the interior surface of the injector receiver  12 . A bore  72  is defined in the lower extremity of the sleeve  70 . The bore  72  is in registry with the injector valve bore  14  in order to accommodate the passage of the valve tip  42  into the combustion chamber. A sealing washer  74  is interposed between the case  40  of the nozzle and tip assembly  38  and the sleeve  70 . The sealing washer  74  and the O-ring  64  each have a compression axis  75 . The compression axes  75  are substantially parallel to the direction of the clamping force exerted by the bolt  68  and the valve springs  20 . Accordingly, no torque moment is applied to the O-ring  64  or the sealing washer  74 . 
     Turning to FIG. 7, in which like numerals denote like components, a second preferred embodiment of the unit injector  30  of the present invention is depicted. The injector retainer assembly  50  in this embodiment is designed to fit between the valves  22  and valve springs  20  that service the same cylinder as the unit injector  30 . Accordingly, no portion of the injector retainer assembly  50  underlies the valve springs  20  as in the embodiment of FIG.  1 . The retainer wall  56  of the injector retainer assembly  50  is supported by two diametrically opposed hold down arms  80 ,  82 . The hold down arms  80 ,  82  have a relatively narrow width dimension in order to accommodate disposition between the plurality of valve springs  20 . Each hold down arm  80 ,  82  is fixedly coupled to the cylinder head  10  by a bolt  84  that is disposed in a bore  86  defined in the hold down ear  80 ,  82  and threaded into a threaded bore defined in the cylinder head  10 . Each bolt  84  has a longitudinal axis  85 . The clamping force exerted by the bolts  84  is exerted along the axis  85 . 
     A gasket  88  is positioned between the underside surface of the hold down arms  80 ,  82  and the surface of the cylinder head  10 . It is significant to note that the gasket  82  provides for the fluid seal at the opening  17  of the high pressure oil rail  16  with the oil passageway  62  of the injector retainer assembly  50 . The gasket  88  has a compression axis  75  depicted transverse to the opening  17  and parallel to axis  85  of bolts  84 . In order to effect this seal the gasket  88  must in all cases be compressed to a desired compression by a force acting parallel to axis  75 . In order to accommodate for the manufacturing tolerances that exist between various unit injectors  30  and various injector receivers  12  defined in the cylinder head  10 , a crushable barrel seal  90  is utilized. As depicted in FIG. 8, the crushable barrel seal  90  is positioned circumferential to the tip  42  of the unit injector  30  between inner bottom surface  91  of the injector sleeve  70  of the sleeve assembly  52  and an opposing surface  93  of the nozzle and tip assembly  38 . The barrel seal  90  has a compression axis  75  that is substantially parallel to axis  85  of bolts  84  and to axis  75  of gasket  88 . The crushable barrel seal  90  has a crushable member  92  that is preferably formed in the manner of a sleeve having a bore  95  defined along the compression axis  75 . The crushable member  92  is preferably formed of a metallic material. The crushable barrel seal  90  has a sealing member  94  bonded to the interior surface of the bore  95  defined within the crushable member  92 . The sealing member is preferably formed of a rubber-like material. The crushable member  92  is substantially non-resilient, making the barrel seal  90  a single use device. 
     In operation, the sleeve  70  of the sleeve assembly  52  is positioned in the injector receiver  12 . The unit injector  30  is then positioned within the sleeve  70  with the uncrushed crushable barrel seal  90  positioned between surfaces  91  and  93 . The bores  86  defined in the hold down arms  80 ,  82  are brought into registry with the threaded bore  96  defined in the cylinder head  10 . The bolts  84  are then threaded into the threaded bores  96  exerting a force aligned with axis  85  of bolts  84 . As the bolts  84  are snugged down to achieve the desired compression of the gasket  88 , the crushable barrel seal  90  is slowly crushed along compression axis  75  to achieve the bowed configuration depicted in FIG.  8 . As the crushable member  92  is bowed, the sealing member  94  is pressed firmly against the exterior surface of the tip  42 , thereby assisting in forming the fluid seal. Once the gasket  88  is compressed a desired amount along compression axis  75 , the bolts  84  are no longer snugged and the degree of crush of the crushable barrel seal  90  is set. Since the compressive force exerted by the bolts  84  along axis  85  is parallel to the compression axis  75  of both the gasket  88  and the barrel seal  90 , no torque moment is applied to either the gasket  88  or the seal  90 . 
     The crushable barrel seal  90  has a height dimension along the compression axis  75  that is sufficient to accommodate a range of the amounts of crush sustainable in order to accommodate the varying manufacturing tolerances that exist in the unit injector  30  and the cylinder head  10 . Throughout this range of crush, an effective fluid seal is formed around the tip  42 . In this manner, the crushable barrel seal  90  accommodates the range of manufacturing tolerances thus permitting the gasket  88  to be compressed as needed in all cases to effect a fluid seal between the high pressure oil rail  16  and the oil passageway  62  defined in the injector retainer assembly  50  while at the same time effecting a fluid seal at tip  42  with barrel seal  90 . 
     A third preferred embodiment of the unit injector  30  of the present invention is depicted in FIG.  9 . Like numerals in FIG. 9 denote like components. The housing of the unit injector  30  depicted in FIG. 9 includes a single hold down arm  100 . The hold down arm  100  has an oil passageway  62  defined therein to fluidly couple the high pressure oil inlet  44  and the high pressure oil rail  16 . 
     A conventional hold down crab partially shown in section at  144  secured to the cylinder head by a bolt (not shown) has an arm portion  146  which applies an axially downward load through the hold down arm  100  to the unit injector  30  to secure it against the pressure of ignition firing, the pressure needed for effective seal crushing, and the hydraulic pressure exerted by high pressure lubricating oil acting upwardly on the hold down arm  100 . The arrow  112  shows the downward force exerted by the hold down crab  144  to be axially aligned with the compression axis  75  of the barrel crushable seal  104 . 
     The barrel crushable seal  104  is interposed between the high pressure oil rail  16  and the oil passage  62  at the opening  17  to the high pressure oil rail  16 . The barrel crushable seal has a generally sleeve like crushable member  106  having a bore  107  axially defined therethrough coaxial with a compression axis  75 . A sealing member  108  is bonded to the interior surface of the crushable member  106 . The barrel crushable seal  104  is disposed in an annular recess  114  defined in the hold down arm  100  and a corresponding annular recess  116  defined in the cylinder head  10 . 
     The barrel crushable seal  104  is depicted in FIG. 2, after a crushing force has been applied thereto parallel to the compression axis  75 . The barrel crushable seal  104  is given a bias at manufacture such that application of a crushing force causes the crushable member  106  to bow outward as depicted in FIG.  2 . Referring to FIG. 3, the barrel crushable seal  104  is given a bias at manufacture in which the crushable member  106  bows inward upon application of a crushing force parallel to the compression axis  75 . 
     Referring again to FIG. 9, a washer seal  110  is disposed between an underside surface of the nozzle and tip assembly  38  and the inside surface of the sleeve  70 . Upon application of a desired compressive force to the washer seal  110 , parallel to the compression axis  75 , an effective fluid seal is formed at the circumference of the tip  42 . The washer seal  110  is best viewed with reference to FIG. 9 a.    
     Assembly and machining tolerances of both the cylinder head  10  and the unit injector  30  are accommodated by the unit injector  30  of FIGS. 9 and 9 a  by means of the barrel crushable seal  104 . As the hold down crab  144  applies downward pressure on the injector retainer assembly  50  parallel to the compression axis  75 , crushing of the barrel crushable seal  104  commences when there is still a gap between the underside surface of the injector retainer assembly  50  of the unit injector  30  and the surface of the cylinder head  10  as indicated by arrows  118 . The hold down crab  144  continues to apply downward force on the unit injector  30  until a desired compression of the washer seal  110  is effected. At this point, a tolerance gap indicated by arrows  120  remains between the underside surface of the injector retainer assembly  50  and the surface of the cylinder head  10 . At this point, sufficient crush has been effected in the barrel crushable seal  104 , as depicted in FIGS. 2 and 3, to effect a fluid seal between the high pressure oil rail  16  and the oil passageway  62  defined in the injector retainer assembly  50 . 
     FIGS. 5 and 5 a  depict a further preferred embodiment of the present invention. The unit injector  30  is positioned proximate to valve springs  20   a ,  20   b  with a single hold down arm  130  extending from the actuator and valve assembly  32  of the unit injector into the gap defined between the valve springs  20   a  and  20   b . The hold down arm  130  is a portion of the injector retainer assembly  50 . The hold down arm  130  is fixedly coupled to a retainer wall  56 , formed to circumferentially encompass the actuator and valve assembly  32  of the unit injector  30 . 
     The hold down arm  130  has a oil passageway  62  defined therein. The oil passageway  62  terminates at the juncture with the cylinder head  10  in a recess  114  that is adapted to receive a crushable type seal as previously described. A single bolt  132  is passed through a bore defined in the hold down arm  130 . The bolt  132  is long enough to threadedly engage a threaded bore defined in the cylinder head  10 . Tightening of the bolt  132  applies a force to the unit injector  30  that is parallel to the compression axis of crushable-type seal disposed in the recess  114 . 
     FIGS. 4 and 6 depict two additional preferred embodiments of crushable seals. FIG. 4 depicts a ring seal  140 . The ring seal  140  has a C-shaped cross section. A bore  142  is defined coaxial with the longitudinal compression axis  144  of the ring seal  140 . 
     The ring seal  140  is depicted in FIG. 4 positioned circumferentially encompassing the tip  42  of the nozzle and tip assembly  38 . The upper margin of the ring seal  140  is in contact with the surface  93 . The lower margin of the ring seal  140  is in contact with the surface  91  comprising the inner lower portion of the sleeve  70 . 
     Turning to FIG. 6, a jumper tube  150  is disposed between the unit injector  30  and the cylinder head  10  in order to seal the juncture between the high pressure oil rail  116  and the oil passageway  62 . The jumper tube  150  has an axial bore  152  defined therein having generally the same diameter as the oil passageway  62  and the high pressure oil rail  16 . The axis of the bore  152  defines the compression axis of the jumper tube  150 . Sealing of the jumper tube  150  is provided by O-rings  154  and  156 . The O-ring  154  sealingly mates with the surface of the recess  114 . The O-ring  156  sealingly mates with the surface of the recess  116 . 
     The jumper tube  150  is designed to accommodate the manufacturing tolerances as previously described, not by crushing but by the spaces defined between the respective ends of the jumper tube  150  and the horizontal surface of the recesses  114 ,  116 , as indicated by the arrows  158 ,  160 . Compression parallel to the compression axis of the jumper tube  150  does not apply a torquing moment to jumper tube  150 . 
     Referring to FIG. 6 a , an alternative method of sealing the jumper tube  150  is depicted. In this case, the beveled edge  162  of the jumper tube  150  compresses a O-ring  164  in the corner of the recess  114 ,  116 . FIG. 6 b  depicts a further means of sealing the jumper tube  150 . In the embodiment of FIG. 6 b , an O-ring groove  166  is defined proximate the horizontal surface of the recess  114 ,  116 . In this case, the jumper tube has a squared corner as distinct from the bellow  162  of FIGS. 6 and 6 a . The squared comer  170  of the jumper tube  150  compresses the O-ring  168  in the O-ring groove  166  to affect the fluid seal. 
     Although a certain specific embodiment of the present invention has been shown and described, it is obvious that many modifications and variations thereof are possible in light of the teachings. It is to be understood therefore that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.