Abstract:
A fuel injector for use in a fuel injection system of an internal combustion engine that includes a body, valve seat, closure member, orifice plate and metering device. The closure member and the valve seat define a sealing surface, located on a virtual circle defining a sealing diameter. The orifice plate includes a third surface, a fourth surface and at least one orifice, located on a virtual circle on the orifice plate defining a first radius and between the third and fourth surfaces. The metering device has first and second faces contiguous to a third face. At least one of the first and third faces are spaced from one of the first and second surfaces of the valve seat to define a plurality of passages. Each passage has an outlet located on a virtual circle defining a second diameter greater than at least one of the first and the sealing diameters.

Description:
FIELD OF THE INVENTION 
     This invention relates to a fuel injector valve seat assembly in general, and more particularly, to a fuel injector valve seat assembly with radially outward leading fuel flow passages feeding a multi-hole orifice disk. 
     BACKGROUND OF THE INVENTION 
     Most modern automotive fuel systems utilize fuel injectors to provide precise metering of fuel for introduction into each combustion chamber. Additionally, the fuel injector atomizes the fuel during injection, breaking the fuel into a large number of very small particles, increasing the surface area of the fuel being injected, and allowing the oxidizer, typically ambient air, to more thoroughly mix with the fuel prior to combustion. The precise metering and atomization of the fuel reduces combustion emissions and increases the fuel efficiency of the engine. 
     An electro-magnetic fuel injector typically utilizes a solenoid assembly to supply an actuating force to a fuel metering valve. Typically, the fuel metering valve is a plunger-style needle valve which reciprocates between a closed position, where the needle is seated in a valve seat to prevent fuel from escaping through a metering orifice into the combustion chamber, and an open position, where the needle is lifted from the valve seat, allowing fuel to discharge through the metering orifice for introduction into the combustion chamber. 
     Typically, a volumetric chamber or sac exists downstream from the discharge tip of the needle and upstream of the orifice. Upon seating of the needle on the valve seat, a volume of fuel, in liquid form, remains within the sac volume, typically during low manifold pressure, at low or ambient tip temperature operating conditions such as during a cold-start. At high temperature, such as during a hot-start, this volume of fuel tends to be in vapor form which leads to difficult starting as this volume would cause the fuel mixture to be richer than anticipated by a fuel injection controller during such a hot-starting operation. Similarly, during a hot shut-down, some of the fuel, however, remains in the sac which vaporizes due to heat soak and causes evaporative emissions which are undesirable. Thus, in order to minimize the amount of fuel in the sac volume that can be vaporized between hot and cold starts, it is believed that this sac volume should be minimized. 
     It is believed that some existing fuel injectors employ a valve seat assembly with a centerline through-hole that feeds directly to an orifice disk via a fairly large sac volume. In addition to the disadvantages described above, it is believed that this large sac volume creates vortices. The growth and decay of both inner and outer vortices result in spray instability, which is detrimental to spray definition, i.e., targeting. Furthermore, the existing single centerline through-hole limits the size of a diameter of a bolt circle. Thus, it is believed that a fuel injector valve seat assembly is needed that can control delivery of fuel while maintaining current sealing diameters, minimizing sac volume, and eliminating vortex generation. 
     SUMMARY OF THE INVENTION 
     The present invention provides a fuel injector for use in a fuel injection system of an internal combustion engine that minimizes sac volume and tends to reduce undesirable vortices in the flow of fuel. In one preferred embodiment of the invention, the fuel injector includes a body, a valve seat, a closure member, an orifice plate, and a metering device. The body has an inlet, an outlet, and a longitudinal axis entering therethrough. The valve seat is disposed proximate the outlet and has a first surface and a second surface. The valve seat includes a valve seat orifice disposed between the first and second surfaces. The closure member is movable along the longitudinal axis between a first position occluding fuel flow and a second position permitting fuel flow through the valve seat orifice. The closure member and the valve seat define a sealing surface in the first position of the closure member. The sealing surface is located on a virtual circle that defines a sealing diameter. The orifice plate is disposed proximate the outlet and has a third surface and a fourth surface. The orifice plate includes at least one orifice disposed between the third and fourth surfaces. The at least one orifice is located on a virtual circle on the orifice plate that defines a first diameter. The metering device is located between the valve seat and the orifice plate. The metering device has a first face and a second face contiguous to a third face. At least one of the first and third faces are spaced from one of the first and second surfaces of the valve seat to define a plurality of passages. Each passage has an inlet to the passage and an outlet from the passage. The outlet of each passage is located on a virtual circle that defines a second diameter greater than at least one of the first diameter and the sealing diameter. 
     The present invention also provides a flow diverter for a fuel injector that tends to reduce flow vortices and maintain spray stability. In another preferred embodiment of the invention, the flow diverter includes a valve seat, an orifice plate, and an insert. The valve seat is disposed along a longitudinal axis and has a first surface and a second surface. The valve seat further includes a valve seat orifice located between the first surface and the second surface and defines an orifice diameter with respect to the longitudinal axis. The orifice plate is disposed on the longitudinal axis and has at least two orifices. Each orifice of the at least two orifices are located at a first diameter from the other orifice. The insert is disposed along the longitudinal axis between the valve seat and the orifice plate. The insert has an annular portion coupled to a main portion, which protrudes into the valve seat orifice. The main portion has a first face spaced from one of the first and second surfaces of the valve seat to define at least two passageways. Each of the at least two passageways are contiguous to at least one virtual circle defining a second diameter. The second diameter is greater than the first diameter. 
     The present invention further provides a method of directing the flow of a fuel injector that maintains spray stability of the fuel exiting the fuel injector. In one preferred embodiment, the fuel injector has a body with a first end and a second end disposed along a longitudinal axis. A valve seat is disposed proximate the second end and has a first surface and a second surface, the second surface disposed about the longitudinal axis to define a valve seat orifice. A closure member movable along the longitudinal axis between a first position blocking fuel flow through the valve seat and a second position permitting fuel flow through the valve seat, the closure member defining, in the first position, a sealing diameter on the first surface of the valve seat. An orifice plate located proximate the second end, the orifice plate having at least two orifices located on a virtual circle defining a first diameter, and a metering device having an annular portion coupled to a main portion, the main portion having a first face and a second face, the first face projecting into the valve seat orifice and being spaced from the second surface of the valve seat to define at least one passage between the main portion and the second surface of the valve seat. In the preferred embodiment, the method can be achieved by directing fuel through the at least one passageway having a portion disposed on a virtual circle defining a second diameter greater than at least one of the first diameter and the sealing diameter; causing the fuel to flow towards the longitudinal axis; and diverting the fuel through the at least one orifice of the orifice plate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain the features of the invention. 
     FIG. 1A is a side view of a fuel injector according to a preferred embodiment. 
     FIG. 1B is a side view, in enlarged cross-section, of the valve seat, closure member, insert, and orifice plate of FIG.  1 A. 
     FIG. 2 is a side view of an alternative assembly of FIG.  1 B. 
     FIG. 3 is an orthogonal view of the metering device of FIG.  2 . 
     FIG. 4 is an exploded view of the valve seat, metering device, and orifice plate of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1A illustrates a side view of a fuel injector  10  according to a preferred embodiment. The fuel injector  10  includes a body  12 , through which a longitudinal axis A extends. An inlet  14  and an outlet  20  are disposed in the body  12  along the longitudinal axis A. A fuel injector of the type with which the preferred embodiments can be used is shown in U.S. Pat. No. 5,494,225 issued on Feb. 27, 1996, which is incorporated in its entirety herein by reference. Referring to FIG. 1B, a valve seat  30  is disposed proximate the outlet  20 . The valve seat  30  includes a valve seat orifice  34 . The valve seat  30  includes a first seat surface  32   a , which slope radially inwardly and downwardly toward the valve seat orifice  34 , which is oblique to the longitudinal axis A. The valve seat  30  also includes a second seat surface  32   b  whose surface defines a valve seat orifice  34 . The terms “inwardly” and “outwardly” refer to directions toward and away from, respectively, the longitudinal axis A. The valve seat orifice  34  is disposed between the first and second seat surfaces  32   a ,  32   b  of the valve seat  30 . 
     A closure member  40  is disposed along the longitudinal axis A, and is movable along a plurality of positions. The closure member  40  includes a generally spherical tip  42 , and the closure member  40  can be a needle-type, as shown in FIG. 1B or the closure member  40   a  may be a ball-type assembly, as shown in FIG.  2 . The plurality of positions include an open position, (not shown) and a closed position, as shown in FIG.  1 B and FIG.  2 . In the closed position, the spherical tip  42  contacts a portion of the valve seat  30 , thus defining a sealing surface  36 . The sealing surface  36  is located on a virtual circle that defines a sealing diameter φ 1  about the longitudinal axis A. In the closed position, the closure member  40  occludes fuel flow through the valve seat  30 . In the open position, the spherical tip  42  does not contact the sealing surface  36 , and thus the closure member  40  permits flow through the valve seat  30 . 
     An orifice plate  50  is disposed proximate the outlet  20  downstream of the valve seat  30 . The orifice plate  50  has a proximate surface  54  and a distal surface  56 . As used with respect to the orifice plate  50 , the terms “proximate” and “distal” refer to a position with respect to the inlet  14 . The orifice plate  50  has at least one exit orifice  52  disposed between the proximate and distal surfaces of the orifice plate  50 . The at least one exit orifice  52  is located on a virtual circle that defines an exit diameter φ 2  about the longitudinal axis A. 
     A metering device  60  is located between the valve seat  30  and the orifice plate  50 . The metering device  60  has a proximate face  62 , which confronts the valve seat  30  and a distal face  64 , which confronts the orifice plate  50 . An intermediate face  63  is contiguous with the distal face  64 . A surface of revolution of the intermediate face  63  of the metering device can form a portion of a cone. At least one of the proximate and intermediate faces  62 , 63  are spaced from one of the first and second surfaces  32   a ,  32   b  of the valve seat  30  to define a plurality of passageways  66 . The valve seat  30  can be formed as an integral part of the metering device  60 . Preferably, the proximate face  62  protrudes into the valve seat orifice  34 . The proximate face  62  can have a substantially concave surface. The proximate face  62  can have a curvature other than concave or can be substantially flat. Preferably, the proximate face  62  has a concave surface. The proximate face  62  and the distal face  64  are in fluid communication by the plurality of passageways  66 . The plurality of passageways  66  are radially spaced from the longitudinal axis A and preferably, are generally oblique with respect to the longitudinal axis A. Each of the plurality of passageways  66  has an inlet  65  to the passageway  66  and an outlet  67  from the passageway  66 . The outlet  67  of each passageway  66  is located on a virtual circle that defines a passageway diameter φ 3  about the longitudinal axis A, which is greater than at least one of the exit diameter φ 2  and the sealing diameter φ 1 . 
     The metering device  60  can include a wall portion  68 , which extends along the longitudinal axis A. The wall portion  68  can have at least two wall surfaces intersecting each other, a proximate wall surface  61  and a distal wall surface  69 . As used with respect to the wall portion  68 , the terms “proximate” and “distal” refer to a position with respect to the inlet  14 . The proximate wall surface  61  and the distal wall surface  69  can cooperate with the second surface  32   b  of the valve seat and the proximate surface  54  of the orifice plate to define a cavity between the valve seat  30  and the orifice plate  50 . The cavity can be in fluid communication with the plurality of passageways  66  and at least one of the plurality of exit orifices  52 . The proximate face  62  of the metering device  60  can extend beyond a surface of revolution generated by the proximate and distal wall surfaces  61 , 69  of the wall portion  68 . The distal face  64  of the metering device  60  can be contiguous to the surface of revolution generated by the proximate and distal wall surfaces  61 , 69  of the wall portion  68 . 
     When the closure member  40  is in the open position, the spherical tip  42  is raised above and separated from the sealing surface  36 , forming an annular opening therebetween, allowing pressurized fuel to flow therethrough and through the plurality of passageways  66  to an intake manifold and therefrom to a combustion chamber (not shown) for combustion. Upon moving the closure member  40  to the closed position, the spherical tip  42  engages the sealing surface  36 , thus occluding the flow of fuel to the combustion chamber (not shown). 
     Another embodiment of the present invention is illustrated in FIGS. 2-4. Like numerals in FIGS. 2-4 are used to indicate like elements. Referring to FIG. 2, a valve seat  30 ′ is disposed proximate the outlet  20 ′. The valve seat  30 ′ includes a valve seat orifice  34 ′. The valve seat  30 ′ includes first and second seat surfaces  32   a ′,  32   b ′, which slope radially inwardly and downwardly toward the valve seat orifice  34 ′, which is oblique to the longitudinal axis A. The terms “inwardly” and “outwardly” refer to directions toward and away from, respectively, the longitudinal axis A. The valve seat orifice  34 ′ is disposed between the seat surfaces  32   a ′,  32   b ′ of the valve seat  30 ′. 
     A closure member  40   a  is disposed along the longitudinal axis A, and is movable along a plurality of positions. The closure member  40   a  can be a ball-type assembly. The plurality of positions include an open position, (not shown) and a closed position, as shown in FIG.  2 . In the closed position, the closure member  40   a  contacts a portion of the valve seat  30 ′ against the valve seat surface  32   a ′, thus defining a sealing surface  36 ′. The sealing surface  36 , is located on a virtual circle that defines a sealing diameter φ 1 ′ about the longitudinal axis A. In the closed position, the closure member  40   a  occludes fuel flow through the valve seat  30 ′. In the open position, the closure member  40   a  does not contact the sealing surface  36 ′, and thus the closure member  40   a  permits flow through the valve seat  30 ′. A closure member guide  70  is disposed upstream of the valve seat  30 ′. The closure member guide  70  permits the closure member  40   a  to move along the plurality of positions but restricts movement of the closure member  40   a  in a lateral direction, i.e., in a direction substantially transverse to the longitudinal axis A. 
     An orifice plate  50 ′ is disposed proximate the outlet  20 ′ downstream of the valve seat  30 ′. The orifice plate  50 ′ has a proximate surface  54 ′ and a distal surface  56 ′. As used with respect to the orifice plate  50 ′, the terms “proximate” and “distal” refer to a position with respect to the inlet  14 . The orifice plate  50 ′ has at least two exit orifices  52 ′ disposed between the proximate and distal surfaces of the orifice plate  50 ′. The at least two exit orifices  52 ′ are located on a virtual circle that defines an exit diameter φ 2 ′ about the longitudinal axis A. 
     A metering device  60 ′ is disposed along the longitudinal axis A between the valve seat  30 ′ and the orifice plate  50 ′. The metering device  60 ′ has a main portion  60 ′ a  and an annular portion  60 ′ b  coupled to the main portion  60 ′ a . The main portion  60 ′ a  protrudes into the valve seat orifice  34 ′. The main portion  60 ′ a  has a proximate face  62 ′, which is spaced from one of the first and second seat surfaces  32   a ′ and  32   b ′ defining at least two passageways  66 . Each of the at least two passageways  66  is contiguous to at least one virtual circle defining a passageway diameter φ 3 ′ about the longitudinal axis A, which is greater than the sealing diameter φ 1 ′. The proximate face  62 ′ confronts the valve seat  30 ′, and a distal face  64 ′ confronts the orifice plate  50 ′. An intermediate face  63 ′ is contiguous with the distal face  64 ′. A surface of revolution of the intermediate face  63 ′ of the metering device can form a portion of a cone. At least one of the proximate and intermediate faces  62 ′,  63 ′ are spaced from one of the first and second seat surfaces  32   a ′,  32   b ′ of the valve seat  30 ′ to define a plurality of passageways  66 ′. The valve seat  30 ′ can be formed as an integral part of the metering device  60 ′. The proximate face  62 ′ protrudes into the valve seat orifice  34 ′. The proximate face  62 ′ can have a substantially concave surface. The proximate face  62 ′ can have a curvature other than concave or can be substantially flat. Preferably, the proximate face  62 ′ has a concave surface. The proximate face  62 ′ and the distal face  64 ′ are in fluid communication by the plurality of passageways  66 ′. The plurality of passageways  66 ′ are radially spaced from the longitudinal axis A and preferably, are generally oblique with respect to the longitudinal axis A. The metering device  60 ′ can include at least one boss portion coupling the annular portion  60 ′ b  to the main portion  60 ′ a  to define at least one arcuate opening  67 ′. Each of the plurality of passageways  66 ′ has an inlet  65 ′ to the passageway  66 ′ and a cavity between the valve seat  30 ′ and the orifice plate  50 ′. The cavity is formed by the at least one arcuate opening  67 ′. The cavity can be in fluid communication with the plurality of passageways  66 ′ and the at least two orifices  52 ′. 
     The metering device  60 ′ can include a wall portion  68 ′, which extends along the longitudinal axis A. The wall portion  68 ′ can have at least two wall surfaces intersecting each other, a proximate wall surface  61 ′ and a distal wall surface  69 ′. As used with respect to the wall portion  68 ′, the terms “proximate” and “distal” refer to a position with respect to the inlet  14 . The proximate wall surface  61 ′ and the distal wall surface  69 ′ can cooperate with the surfaces  32   a ′,  32   b ′ of the valve seat and the proximate surface  54 ′ of the orifice plate to define a cavity between the valve seat  30 ′ and the orifice plate  50 ′. The proximate face  62 ′ of the metering device  60 ′ can extend beyond a surface of revolution generated by the proximate and distal wall surfaces  61 ′,  69 ′ of the wall portion  68 ′. The distal face  64 ′ of the metering device  60 ′ can be disposed within a surface of revolution generated by the at least two wall surfaces  61 ′,  69 ′ of the wall portion  68 ′. Additionally, the distal face  64 ′ extends into the valve seat orifice  34 ′ that is defined by the second valve seat surface  32   b ′. Preferably, the distal face  64 ′ is in a confronting arrangement with the second surface  32   b ′ such that at least one passage is formed therebetween. 
     When the closure member  40   a  is in the open position, the ball assembly is raised above and separated from the sealing surface  36 , forming an annular opening therebetween, allowing pressurized fuel to flow therethrough and through the plurality of passageways  66 ′ to a combustion chamber (not shown) for combustion. Upon moving the closure member  40   a  to the closed position, the ball assembly engages the sealing surface  36 ′, thus occluding the flow of fuel to the combustion chamber (not shown). 
     The operation of the fuel injector  10  is as follows. Like numerals are used to indicate like elements in the drawings. A fuel pump (not shown) provides pressurized fuel flow into the fuel injector  10 . The pressurized fuel enters the fuel injector  10  and passes through a fuel filter (not shown) to an armature (not shown) and to a valve body chamber (not shown). The fuel flows through the valve body chamber (not shown) and to an interface between the spherical tip  42  of the closure member  40  and the sealing surface  36 . In the closed position, shown in FIG.  1 B and FIG. 2, the closure member  40  is biased against the valve seat  30  so that the spherical tip  42  sealingly engages the sealing surface  36 , preventing flow of fuel through the valve seat orifice  34 . 
     In the open position (not shown), a solenoid or other actuating device (not shown), reciprocates the closure member  40  thereby removing the spherical tip  42  of the closure member  40  from the sealing surface  36  of the valve seat  30 . Pressurized fuel flows past the closure member  40  and into the plurality of passageways  66 . The fuel is atomized as it passes through the plurality of exit orifices  52  to the combustion chamber (not shown) for combustion, allowing for better combustion within the combustion chamber (not shown). 
     When a predetermined amount of fuel has been injected into the combustion chamber (not shown), the solenoid or other actuating device (not shown) disengages, allowing the spring (not shown) to bias the closure member  40  to the first position onto the sealing surface  36 , thus occluding flow through the valve seat  30 . 
     While the invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the invention, as defined in the appended claims and their equivalents thereof. Accordingly, it is intended that the invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims.