Patent Publication Number: US-9850869-B2

Title: Fuel injector

Description:
TECHNICAL FIELD OF INVENTION 
     The present invention relates to fuel injectors for supplying fuel to a fuel consuming device; more particularly to such fuel injectors for direct injection of fuel into a combustion chamber of an internal combustion engine, and even more particularly to such fuel injectors with an inward opening valve and a nozzle tip arranged to generate a plume of fuel with a recirculation zone conducive of combustion by a spark plug. 
     BACKGROUND OF INVENTION 
     Modern internal combustion engines typically utilize one or more fuel injectors for metering a precise quantity of fuel to be combusted in respective combustion chambers such that the combustion is initiated with a spark from a spark plug. Combustion of the fuel may be used, for example, to propel a motor vehicle and to generated electricity or drive other accessories in support of operation of the motor vehicle. Fuels in liquid form that are commonly used to power the internal combustion engine include gasoline, alcohol, ethanol, and the like, and blends thereof. Until more recently, fuel injectors commonly referred to as port fuel injectors were predominantly used. Port fuel injectors inject fuel into a port of an intake manifold where the fuel is mixed with air prior to being drawn into the combustion chamber of the internal combustion through an intake valve of the cylinder head. A typical port fuel injector is show in U.S. Pat. No. 7,252,249 to Molnar. The port fuel injector of U.S. Pat. No. 7,252,249; which is typical of port fuel injectors; uses an inward opening valve arrangement which is operated by a solenoid actuator. Fuel that flows past the valve arrangement is metered and shaped by a director plate with holes that are sized and shaped to allow a precise amount of fuel therethrough in such a way as to disperse the fuel into fine droplets which mix with the air. 
     In order to increase fuel economy and reduce undesirable emissions produced by combustion of the fuel, direct injection fuel injectors have been increasing in use. As the name suggests, direct injection fuel injectors inject fuel directly into the combustion chamber. Direct fuel injectors are commonly available with inwardly opening valve arrangements or outwardly opening valve arrangements. Outwardly opening valve arrangements are desirable due to the hollow cone spray structure that is produced which may include a circumferentially located recirculation zone on the outer perimeter of the hollow cone spray structure which provides a stable site for ignition of the fuel by a spark plug. However, the fuel delivered by outwardly opening direct injection fuel injectors is metered by the distance the valve member is moved from the corresponding valve seat rather than by holes of a director plate. Outwardly opening direct injection fuel injectors have typically required the use of piezoelectric actuators for fast and precise valve actuation which is necessary to precisely meter the fuel and to generate the hollow cone spray structure. While piezoelectric actuators may be effective, they are costly to implement. Advancements in solenoid technology have allowed implementation of solenoid actuators in outwardly opening direct injection fuel injectors; an example of which is shown in United States Patent Application Publication No. US 2011/0163189 A1 to Mancini et al. Even though a solenoid actuator is used, which is less costly than a piezoelectric actuator, the valve components must be made with a high degree of precision which adds to manufacturing costs and complexity. U.S. Pat. No. 8,543,951 to Mieney et al. shows an inwardly opening direct injection fuel injector which includes a nozzle tip with individual holes which are sized and shaped to allow a precise amount of fuel therethrough. Since the fuel is metered by the holes in the nozzle tip, the valve components may be made with a lesser degree of precision than the outwardly opening arrangement. However, the individual holes in the nozzle tip do not allow a beneficial hollow cone spray structure to be produced as is produced by outwardly opening direct injection fuel injectors. 
     What is needed is an inward opening direct injection fuel injector which minimizes or eliminates one or more of the shortcomings set forth above. 
     SUMMARY OF THE INVENTION 
     Briefly described, a fuel injector is provided for supplying fuel to a fuel consuming devise. The fuel injector includes a fuel inlet for receiving the fuel, a nozzle tip for dispensing the fuel from the fuel injector, a conduit for communicating the fuel from the fuel inlet to the nozzle tip, a valve seat, and a valve member selectively seatable and unseatable with the valve seat for selectively preventing and permitting fuel flow out of the nozzle tip. The nozzle tip comprises a non-circular recess on a downstream side thereof and a metering hole on an upstream side thereof opening into the non-circular recess to allow fuel to exit the nozzle tip, the metering hole having a smaller area than the non-circular recess. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       This invention will be further described with reference to the accompanying drawings in which: 
         FIG. 1  is a cross-sectional view of a fuel injector in accordance with the present invention; 
         FIG. 2  is an enlargement of a portion of  FIG. 1 ; 
         FIG. 3A  is an axial end view of a nozzle tip of the fuel injector of  FIG. 1  in accordance with the present invention; 
         FIG. 3B  is an isometric view of a portion of the nozzle tip of  FIG. 3A ; 
         FIG. 3C  is a straight-on view of a portion of  FIG. 3B ; 
         FIG. 4A  is a variant of  FIG. 3B ; 
         FIG. 4B  is a straight-on view of a portion of  FIG. 4A ; 
         FIG. 5  is an axial end view of another nozzle tip in accordance with the present invention; 
         FIG. 6  is an axial end view of another nozzle tip in accordance with the present invention; 
         FIG. 7  is an axial end view of another nozzle tip in accordance with the present invention; 
         FIG. 8  is an enlargement of a nozzle hole of the nozzle tip in accordance with the present invention; 
         FIG. 9  is an enlargement of another nozzle hole; 
         FIG. 10  is an enlargement of another nozzle hole; and 
         FIG. 11  is a spray plume generated by a recirculation generating nozzle hole of the fuel injector in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     In accordance with a preferred embodiment of this invention and referring to  FIG. 1 , a fuel injector  10  is shown for supplying fuel to a fuel consuming device which is illustrated as an internal combustion engine  12 . Fuel injector  10  extends along a fuel injector axis  14  and includes a fuel inlet  16  for receiving fuel, a nozzle tip  18  for dispensing fuel from fuel injector  10 , a conduit  20  for communicating fuel from fuel inlet  16  to nozzle tip  18 , and a valve assembly  22  for selectively preventing and permitting fuel from exiting nozzle tip  18 . Nozzle tip  18  may be disposed within a combustion chamber  24  of internal combustion engine  12  for injection of fuel directly within combustion chamber  24  where the fuel is ignited, for example, by a spark plug  26 . It should be noted that the location of fuel injector  10  and spark plug  26  relative to combustion chamber  24  as shown in the figures is for illustrative purposes only and the location of fuel injector  10  and/or spark plug  26  relative to combustion chamber  24  may be vary according to engine design. 
     With continued reference to  FIG. 1  and with additional reference to  FIG. 2  which is an enlarged view of a portion of  FIG. 1 , valve assembly  22  includes a valve seat  28  formed within nozzle tip  18  which is substantially cup-shaped. Valve seat  28  is centered about fuel injector axis  14 . Valve assembly  22  also includes a pintle  30  which is coaxial with valve seat  28  and which defines a valve member  32  at one end of pintle  30 . Pintle  30 , and consequently valve member  32 , is reciprocated alone fuel injector axis  14  within conduit  20  by an actuator which is illustrated as solenoid  34 . Reciprocation of pintle  30  causes valve member  32  to selectively seat and unseat with valve seat  28  for selectively preventing and permitting fuel flow out of nozzle tip  18 . Actuators for reciprocating a pintle in a fuel injector are well known to those skilled in the art of fuel injectors, consequently, solenoid  34  will not be discussed further herein. 
     Nozzle tip  18  includes one or more nozzle holes  36  extending therethrough to allow fuel that passes by valve seat  28  when valve member  32  is not seated with valve seat  28  to exit nozzle tip  18 . Nozzle holes  36  may extend through a nozzle tip surface  38  which is not perpendicular to fuel injector axis  14 . Nozzle tip surface  38  is on the exterior of nozzle tip  18  and may be substantially dome-shaped or a portion of a sphere as shown. The Inventors have discovered configurations of nozzle holes  36  which produce spray plumes that are beneficial to combustion of the fuel within combustion chamber  24  as will be described by exemplary embodiments in the paragraphs that follow. 
     Reference will now be made to  FIG. 3A  which shows an axial view of nozzle tip  18 ,  FIG. 3B  which shows an isometric view of a portion of nozzle tip  18 , and  FIG. 3C  which shows a straight-on view of a portion of  FIG. 3B . As shown, nozzle holes  36  are centered on a circular centerline  40  which is centered about fuel injector axis  14 . Nozzle holes  36  comprise a plurality of main nozzle holes  42  (for clarity, only select main nozzle holes  42  have been labeled) and a recirculation generating nozzle hole  44 . Main nozzle holes  42  may be spaced substantially equally, i.e. the angular spacing between adjacent main nozzle holes  42  is substantially the same for each main nozzle hole  42 . Each one of the plurality of main nozzle holes  42  may be substantially identical, consequently, the subsequent description will refer to one main nozzle hole  42 . Main nozzle hole  42  comprises a circular main nozzle hole recess  46  formed in nozzle tip surface  38  such that main nozzle hole recess  46  is centered on circular centerline  40 . Nozzle tip surface  38  is on the downstream side of nozzle tip  18 . Main nozzle hole  42  also comprises a circular main nozzle metering hole  48  that extends through nozzle tip  18  and opens into main nozzle hole recess  46  such that main nozzle metering hole  48  is centered on circular centerline  40 . Main nozzle hole  42  has a smaller area than main nozzle hole recess  46 . Main nozzle metering hole  48  is sized to provide a desired flow of fuel from main nozzle hole  42  when valve member  32  is unseat with valve seat  28 . 
     Recirculation generating nozzle hole  44  comprises a non-circular recirculation generating nozzle hole recess  50  formed in nozzle tip surface  38 . Recirculation generating nozzle hole recess  50  may be arc-shaped as shown such that recirculation generating nozzle hole recess  50  is centered on circular centerline  40  and has a recess length  52  along circular centerline  40  that is greater than a recess width  54  across circular centerline  40 . Recirculation generating nozzle hole recess  50  extends from a top  56  that is proximate to nozzle tip surface  38  to a bottom  58  that is distal from nozzle tip surface  38 . Recirculation generating nozzle hole recess  50  may be substantially consistent in size from bottom  58  to top  56 . Alternatively, recirculation generating nozzle hole recess  50  may diverge or flare outward from bottom  58  to top  56 . As shown, each end of recirculation generating nozzle hole recess  50  may terminate in a radius. Recirculation generating nozzle hole  44  also comprises a plurality of circular recirculation generating metering holes  60  that extend through nozzle tip  18  and open into recirculation generating nozzle hole recess  50  such that recirculation generating metering holes  60  are centered on circular centerline  40  and such that the spacing between adjacent recirculation generating metering holes  60  is the same for each recirculation generating metering hole  60 . While three recirculation generating metering holes  60  are shown, it should be understood that a lesser or greater number may be provided. Recirculation generating metering holes  60  are sized to provide a desired flow of fuel from recirculation generating nozzle hole  44  when valve member  32  is unseat with valve seat  28  and may be sized to be smaller in diameter than main nozzle metering hole  48 . Recirculation generating metering holes  60  together have a smaller area than recirculation generating nozzle hole recess  50 . Fuel exiting recirculation generating metering holes  60  is shaped and dynamically affected by recirculation generating nozzle hole recess  50  to produces a plume of fuel with a recirculation zone conducive of combustion by spark plug  26 . Fuel injector  10  may be oriented within combustion chamber  24  such that spark plug  26  is located within the recirculation zone generated by recirculation generating nozzle hole  44 . 
     Alternatively, as shown in  FIGS. 4A and 4B , recirculation generating metering holes  60  may be substituted with a single non-circular recirculation generating metering hole  60 ′. As shown, recirculation generating metering hole  60 ′ is arc-shaped such that recirculation generating metering hole  60 ′ is centered on circular centerline  40 . The perimeter of recirculation generating metering hole  60 ′ may be offset from the perimeter of bottom  58  a consistent distance, i.e. the perpendicular distance from any point on the perimeter of recirculation generating metering hole  60 ′ outward to the outer perimeter of bottom  58  is the same as the perpendicular distance from any other point on the perimeter of recirculation generating metering hole  60 ′ outward to the outer perimeter of bottom  58 . Fuel exiting recirculation generating metering hole  60 ′ is shaped and dynamically affected by recirculation generating nozzle hole recess  50  to produces a plume of fuel with a recirculation zone conducive of combustion by spark plug  26 . 
     Reference will now be made to  FIG. 5  which shows a second embodiment of a nozzle tip  118 . Nozzle tip  118  is substantially the same as nozzle tip  18  described with reference to  FIGS. 3A, 3B, and 3C  except that main nozzle holes  42  are substituted with a plurality of recirculation generating nozzle holes  44 . Each recirculation generating nozzle hole  44  may be spaced substantially equally, i.e. the angular spacing between adjacent recirculation generating nozzle holes  44  is substantially the same for each recirculation generating nozzle hole  44 . Recirculation generating nozzle holes  44  may include a plurality of recirculation generating metering holes  60  as described previously with reference to  FIG. 3B  or a recirculation generating metering hole  60 ′ which was describe previously with reference to  FIGS. 4A and 4B . Providing a plurality of recirculation generating nozzle holes  44  centered about circular centerline  40  may provide a better distribution of fuel in combustion chamber  24  which may help to minimize wall wetting of combustion chamber  24  and to minimize interaction between the fuel and the intake valves (not shown), exhaust valves (not shown), and spark plug  26 . While three recirculation generating nozzle holes  44  are shown, it should be understood that a lesser or greater number may be provided. 
     Reference will now be made to  FIG. 6  which shows a third embodiment of a nozzle tip  218 . Nozzle tip  218  is substantially the same as nozzle tip  118  described with reference to  FIG. 5  except that nozzle tip  218  includes a plurality of main nozzle holes  42  centered on a circular centerline  262  which is concentric to circular centerline  40 . As shown, main nozzle holes  42  are located radially inward from recirculation generating nozzle holes  44 ; however, this relationship may be reversed such that main nozzle holes  42  are located radially outward from recirculation generating nozzle holes  44 . Also as shown, each main nozzle hole  42  may be positioned to be radially aligned with the space between adjacent recirculation generating nozzle holes  44 . The spray plumes produced by main nozzle holes  42  help to cover the gaps between the plumes produced by recirculation generating nozzle holes  44 , thereby better approximating the hollow cone spray structure that is produced by outwardly opening direct injection fuel injectors. 
     Reference will now be made to  FIG. 7  which shows a fourth embodiment of a nozzle tip  318 . Nozzle tip  318  is substantially the same as nozzle tip  218  except that nozzle tip  318  includes a plurality of recirculation generating nozzle holes  44  centered on circular centerline  262 . As shown, circular centerline  262  is located radially inward from circular centerline  40 ; however, this relationship may be reversed such that circular centerline  40  is located radially outward from circular centerline  262 . Also as shown, each recirculation generating nozzle hole  44  that is located on circular centerline  262  may be positioned to be radially aligned with the space between adjacent recirculation generating nozzle holes  44  that are located on circular centerline  40 . The spray plumes produced by recirculation generating nozzle holes  44  centered on circular centerline  262  help to cover the gaps between the plumes produced by recirculation generating nozzle holes  44  centered on circular centerline  40 , thereby better approximating the hollow cone spray structure that is produced by outwardly opening direct injection fuel injectors. 
     Reference will now be made to  FIG. 8  which shows a main nozzle hole  42 ′ which may be used as an alternative to main nozzle hole  42 . Main nozzle hole  42 ′ differs from main nozzle hole  42  in that main nozzle hole  42  includes a main nozzle hole recess  46 ′ in nozzle tip surface  38  such that main nozzle hole recess  46 ′ is stepped, thereby defining a lower main nozzle hole recess  46   a′  and an upper main nozzle hole recess  46   b ′. Lower main nozzle hole recess  46   a′  and upper main nozzle hole recess  46   b′  are separated by a shoulder  62 . Main nozzle hole  42 ′ also includes main nozzle metering hole  48  just as main nozzle hole  42  does. The stepped nature of main nozzle hole  42 ′ may be helpful in breaking up and dispersing fuel. 
     Reference will now be made to  FIG. 9  which shows a recirculation generating nozzle hole  44 ′ which may be used as an alternative to recirculation generating nozzle hole  44 . Recirculation generating nozzle hole  44 ′ differs from recirculation generating nozzle hole  44  in that recirculation generating nozzle hole  44 ′ includes a recirculation generating nozzle hole recess  50 ′ in nozzle tip surface  38  such that recirculation generating nozzle hole recess  50 ′ is stepped, thereby defining a lower recirculation generating nozzle hole recess  50   a′  and an upper recirculation generating nozzle hole recess  50   b ′. Lower recirculation generating nozzle hole recess  50   a′  and upper recirculation generating nozzle hole recess  50   b′  are separated by a shoulder  64 ′ which surrounds the entire perimeter of lower recirculation generating nozzle hole recess  50   a′  and upper recirculation generating nozzle hole recess  50   b ′. Recirculation generating nozzle hole  44 ′ also includes recirculation generating metering hole  60 ′, or alternatively, recirculation generating metering hole  60 , just as recirculation generating nozzle hole  44  does. The stepped nature of recirculation generating nozzle hole  44 ′ may further help to shape and dynamically affect the fuel to produce a plume of fuel with a recirculation zone conducive of combustion by spark plug  26 . 
     Reference will now be made to  FIG. 10  which shows a recirculation generating nozzle hole  44 ″ which may be used as an alternative to recirculation generating nozzle hole  44  or recirculation generating nozzle hole  44 ′. Recirculation generating nozzle hole  44 ″ differs from recirculation generating nozzle hole  44 ′ in that recirculation generating nozzle hole  44 ″ includes a recirculation generating nozzle hole recess  50 ″ in nozzle tip surface  38  such that recirculation generating nozzle hole recess  50 ″ is stepped, thereby defining a lower recirculation generating nozzle hole recess  50   a″  and an upper recirculation generating nozzle hole recess  50   b ″. Lower recirculation generating nozzle hole recess  50   a″  and upper recirculation generating nozzle hole recess  50   b″  are separated by a shoulder  64 ″ only at each end of lower recirculation generating nozzle hole recess  50   a″  and upper recirculation generating nozzle hole recess  50   b″  with no shoulder therebetween. Recirculation generating nozzle hole  44 ″ also includes recirculation generating metering hole  60 ′, or alternatively, recirculation generating metering hole  60 , just as recirculation generating nozzle hole  44  does. Including shoulders  64 ″ only at the ends of lower recirculation generating nozzle hole recess  50   a″  and upper recirculation generating nozzle hole recess  50   b″  may allow fuel spray to expand laterally to a greater extend in order to form a more complete curtain of fuel. 
     Reference will now be made to  FIG. 11  which shows a spray plume  66  produced within combustion chamber  24  by a representative recirculation generating nozzle hole  44 ,  44 ′ of fuel injector  10 . As can be seen, the end of spray plume  66  produces a recirculation zone  68  where spray plume  66  wraps around and begins to flow back slightly toward fuel injector  10 . Recirculation zone  68  is in close proximity to spark plug  26  and may closely resemble the highly desirable recirculation zone produced in an outward opening direct injection fuel injector. Consequently, recirculation zone  68  provides a stable and robust ignition site for ignition by spark plug  26  and may promote long life of spark plug  26 . However, fuel injector  10  may be manufactured more economically since fuel injector  10  is an inward opening direct injection fuel injector. 
     While fuel injector  10  has been described in terms of use in a spark ignited direct injection arrangement, it should be understood that other uses are contemplated. For example only, fuel injector  10  may be used in a port injection arrangement and may also be used in compression ignition arrangements which may also include using diesel as a fuel. 
     While this invention has been described in terms of the preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow.