Patent Publication Number: US-7591246-B2

Title: Isolated fuel delivery system

Description:
TECHNICAL FIELD 
     The present invention relates to fuel delivery systems for internal combustion engines. 
     BACKGROUND OF THE INVENTION 
     Fuel delivery systems for internal combustion engines are available in many different varieties. One of the more common of which is the port fuel injection system. The port fuel injection system utilizes a plurality of fuel injectors each of which delivers a predetermined amount of fuel to the inlet port of an associated combustion chamber. In such systems, the fuel injectors are mounted in sockets or injector bosses of a manifold or fuel rail, which operates to communicate fuel to each of the injectors. 
     Recent advances in fuel delivery and combustion research has allowed direct injection, or DI, fuel delivery systems to increase in popularity. The DI fuel delivery system provides a fuel injector within the cylinder head of the internal combustion engine. The DI fuel injector operates to inject a predetermined amount of fuel directly into the combustion chamber. Since the gas pressure within the combustion chamber is orders of magnitude greater than that of the intake port, the DI fuel rail and fuel injector operate at a much higher fuel pressure than similar components within the port fuel injection system. The DI fuel delivery system enables higher peak power levels, improved fuel economy, and lower emissions. These beneficial aspects of the DI fuel delivery system are a result of the precise metering of the fuel injected into the combustion chamber as well as improved intake airflow into the combustion chamber. 
     The electromagnetic fuel injectors of the DI fuel delivery system deliver fuel to the combustion chamber in metered pulses, which are timed to control the amount of fuel delivered and to coordinate such delivery with specific points of the operational cycle of the engine. The sequential energization of the fuel injectors may operate to induce pressure pulsations within the fuel rail, which may produce noise-emitting vibrations. The transmission of vibrational energy generated within the DI fuel delivery system to the engine structure may follow two paths; from the fuel injector to the cylinder head and from the fuel rail to the respective attachment point, which is most likely the cylinder head. 
     SUMMARY OF THE INVENTION 
     Accordingly, the isolated fuel delivery system of the present invention reduces the transmission of noise producing, high frequency vibrations from the fuel injector and fuel rail to the engine. 
     Provided is an isolated fuel delivery system for an internal combustion engine having a cylinder head and an intake manifold. The isolated fuel delivery system includes a fuel rail operable to deliver fuel to at least one fuel injector. The isolated fuel delivery system also includes at least one clamping member operable to removably attach the fuel rail to the internal combustion engine. An isolating member is at least partially disposed between the clamping member and the fuel rail. The isolator member operates to absorb vibrations of the fuel rail. 
     Additionally, a first and a second of the at least one clamping members may be provided, with each having a first and second edge. The first and second clamping members may have a lip portion at least partially disposed about at least one of the first and second edges. The lip portion is spaced from the fuel rail by a predetermined amount and is operable to locate and limit the movement of the isolating member with respect to the first and second clamping members. The clamping member may permit the fuel rail to move with respect to the clamping member to enable changes in orientation of the fuel rail and the fuel injector. The clamping member may be integral with one of the cylinder head and the intake manifold and may extend substantially the length of the fuel rail. 
     Additionally, an isolated fuel delivery system for an internal combustion engine having a cylinder head and an intake manifold is provided having a fuel rail operable to deliver fuel to at least one fuel injector. The isolated fuel delivery system also includes a one-piece clamping member having a clamping portion with a first and a second mounting flange extending therefrom and defining a bore operable to receive a fastener. The fastener is operable to removably attach the fuel rail to the internal combustion engine. An isolating member is at least partially disposed between the clamping portion and the fuel rail and operates to isolate the fuel rail. 
     The isolated fuel delivery system may further include a shim block disposed between the first and second mounting flanges and operable to engage a first tab of the first mounting flange and a second tab of the second mounting flange such that the shim block and the one-piece clamping member cooperate to provide pre-compression to the isolating member. The one-piece clamping member may extend substantially the length of the fuel rail. 
     Also provided is an isolated fuel delivery system for an internal combustion engine having a fuel rail operable to deliver fuel to at least one fuel injector. The fuel rail also includes at least one mounting boss portion. The mounting boss portion defines a bore that is dimensioned to receive a fastener. The fastener is operable to removably attach the fuel rail to the engine. Also provided is a plurality of isolating members, each disposed at a respective opposite axial end of the mounting boss and operable to damp the vibrations of the fuel rail. 
     Any of the above described embodiments of the isolated fuel delivery system may include an isolating ring assembly disposed between the fuel injector and the cylinder head and operable to isolate the fuel injector. The isolating ring assembly may be an elastomeric isolating ring member disposed between two stiffening members. Additionally, the isolating ring member may be a metal spring such as a Bellville-type or wave washer. 
     The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  is a fragmentary top elevational view of an isolated fuel delivery system consistent with the present invention illustrating a two-piece clamp assembly; 
         FIG. 1   b  is a fragmentary cross sectional view of the isolated fuel delivery system shown in  FIG. 1 , taken along line A-A of  FIG. 1   a;    
         FIG. 2  is a fragmentary and partially exploded cross sectional view of an alternate embodiment of the isolated fuel delivery system shown in  FIG. 1  having a first clamping member and a second clamping member integrated into an intake manifold and a cylinder head, respectively; 
         FIG. 3  is a fragmentary perspective view of another embodiment of the isolated fuel delivery system of the present invention illustrating a one-piece clamp design; 
         FIG. 4  is a fragmentary cross sectional view of yet another embodiment of the isolated fuel delivery system of the present invention illustrating a clamp design similar to the one-piece clamp shown in  FIG. 3 ; 
         FIG. 5  is a fragmentary cross sectional view of still another embodiment of the isolated fuel delivery system illustrating a fuel rail having a mounting portion with isolating members disposed on each side of the mounting boss portion; 
         FIG. 6   a  is a perspective view of an isolating member operable to isolate a fuel rail; and 
         FIG. 6   b  is a perspective view of an isolating ring member operable to isolate a fuel injector from the cylinder head. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings wherein like reference numbers represent like components throughout the several figures, there is shown in  FIG. 1   a  an isolated fuel delivery system  10  having a fuel rail  12 , a fuel injector  14 , and a clamp assembly  16 . The fuel rail  12  operates as a conduit to communicate pressurized fuel to the fuel injector  14 . Although only one fuel injector  14  is shown in  FIG. 1   a , those skilled in the art will recognize that the fuel rail  12  may operate as a manifold to provide multiple fuel injectors  14  with pressurized fuel. A fuel injector boss  17  is operable to retain one end of the fuel injector  14  with respect to the fuel rail  12 , while another end of the fuel injector  14  is disposed within a cylinder head  18 . The fuel injector  14  has an injector seal  19 , shown in dashed lines, to contain pressurized fuel within the fuel rail  12 . The cylinder head  18  defines an injector bore  20 , which is dimensioned such that the fuel injector tip  22  can pass though the head  18  to communicate with a combustion chamber  24 . 
     The fuel injector  14  operates to deliver a predetermined amount of fuel, at a specific point in the engine cycle, directly to the combustion chamber  24 . An annular combustion seal  26  is provided about the fuel injector tip  22  to disallow the pressurized gasses within the combustion chamber  24  from traversing the injector bore  20 . A circumferential land  28  is provided within the injector bore  20  as a means to locate the fuel injector  14  within the cylinder head  18 . Disposed between the land  28  and the fuel injector  14  is an isolating ring assembly  30 . The isolating ring assembly  30  includes an isolating ring member  32  disposed between first and second stiffening members  34  and  35 , respectively. The isolating ring member  32  may be made from a viscoelastic material or an elastic material such as rubber. The first and second stiffening members  34  and  35  may be made of any material with sufficient structural rigidity, such as steel, aluminum, composites, etc., to distribute axial forces to the isolating ring member  32 . The first and second stiffening members  34  and  35  may be bonded to the isolating ring member  32  using adhesives known in the art. In addition to providing a measure of vibratory isolation to the isolated fuel delivery system  10 , the isolating ring assembly  30  operates to limit the heat transfer between the cylinder head  18  and the fuel within the isolated fuel delivery system  10 . An alternate method of isolating the fuel injector  14  from the cylinder head  18  could employ a Belleville-type or wave washer operable to provide compliance and therefore a measure of isolation within the fuel injector  14  to cylinder head  18  interface. 
     The clamp assembly  16  includes a first clamping member  36  and a second clamping member  38 , both of which cooperate to removably attach the fuel rail  12  to one of the cylinder head  18 , as shown in  FIGS. 1   a  and  1   b  or to an intake manifold  40 , as shown in  FIG. 2  and described more particularly hereinafter. An isolating member  42  is at least partially disposed between each of the first and second clamping members  36  and  38 , respectively, and the fuel rail  12 . The isolating member  42  operates to isolate the fuel rail  12  from the cylinder head  18 . The first and second clamping members  36  and  38  each have a first edge  44  and a second edge  46 , each of which may have a radially inwardly projecting annular lip portion  48  an  48 ′, respectively. The lip portions  48  and  48 ′ operate to contain and position the isolating member  42  within the first and second clamping member  36  and  38 . The annular lip portions  48  and  48 ′ are spaced from the fuel rail  12  by a predetermined distance sufficient to prevent contact between the fuel rail  12  and the first and second clamping members  36  and  38  when the clamp assembly  16  is compressed. The annular lip portions  48  and  48 ′ operate to limit the motion of the fuel rail  12  should the isolating member  42  become overloaded or overstressed. A hex head fastener or fastener  50  may be used to secure the fuel rail  12  to the cylinder head  18 . Although a hex head fastener is shown in  FIG. 1   a , those skilled in the art will recognize that alternate fastening methods may be employed, such as a stud and nut. 
     Referring now to  FIG. 1   b  a fragmentary cross sectional view of the isolated fuel delivery system  10  shown in  FIG. 1   a  is illustrated. The cross section is taken along line A-A of  FIG. 1   a  and further illustrates the interrelation between the first and second clamping members  36  and  38 , the fuel rail  12 , and the isolating member  42 . 
     Referring now to  FIG. 2 , there is shown an isolated fuel delivery system  10 A. In this embodiment, a clamp assembly  16 ′ has a first clamping member  36 ′ that is integral with the intake manifold  40  of the internal combustion engine (not shown). Additionally, the clamp assembly  16 ′ has a second clamping member  38 ′ that is integral with the cylinder head  18 . The intake manifold  40  is lowered, in the direction indicated by arrow  39 , onto the cylinder head  18  thereby capturing or retaining the isolating member  42  and the fuel rail  12 . By incorporating the first and second clamping members  36 ′ and  38 ′ into the intake manifold  40  and the cylinder head  18 , respectively, the need for the fastener  50  (shown in  FIGS. 1   a  and  1   b ) is obviated. 
     An isolating ring assembly  30 ′ is shown in  FIG. 2 . The isolating ring assembly  30 ′ includes the isolating ring member  32  disposed between a first and a second stiffening member  34 ′ and  35 ′, respectively. As shown, the first stiffening member  34 ′ has a tab portion  52  extending axially from the outer periphery of the first stiffening member  34 ′. The tab portion  52  operates to contain and locate the isolating ring member  32  within the isolating ring assembly  30 ′. Additionally the tab portion  52  may be dimensioned to operate to set the crush limit of the isolating ring assembly  30 ′. In operation, as the fuel pressure within the fuel rail  12  increases and the engine load increases, the need to isolate the fuel delivery system  10 A becomes less important as various other sounds emitted by the powertrain are greater than those emanating from the fuel delivery system  10 A. Therefore, as the fuel pressure rises within the fuel rail  12 , the fuel injector  14  will exert additional force against the isolating ring assembly  30 ′ causing the tab portion  52  to “ground” against the second stiffening member  35 ′. Those skilled in the art will recognize that the lip portion  52  may be integrated into the first stiffening ring member  34 ′, as shown in  FIG. 2 , and/or second stiffening member  35 ′. The tab portion  52  may span substantially the entire circumference of one or both of the first and second stiffening members  34 ′ and  35 ′ or any portion thereof. The first and second stiffening members  34 ′ and  35 ′ may be made of any material with sufficient structural rigidity, such as steel, aluminum, composites, etc., to distribute axial forces to the isolating ring member  32 . Additionally, the first and second stiffening members  34 ′ and  35 ′ may be bonded to the isolating ring member  32 . 
     In  FIG. 3  there is shown an isolated fuel delivery system  10 B. The isolated fuel delivery system  10 B includes a one-piece clamping member  54  having a clamping portion  56  defining a cavity with generally the same cross sectional shape as the fuel rail  12 , and operable to contain the fuel rail  12  with the isolating member  42  disposed therebetween. The clamping portion  56  has a first flange portion  58  and a second flange portion  60  extending therefrom and operable to provide an attachment provision to removably attach the isolated fuel delivery system  10 B to the cylinder head  18 . A bore  62  is defined by both the first and second flange portions  58  and  60 , and is dimensioned to receive a fastener, such as the hex head fastener  50 , shown in  FIGS. 1   a  and  1   b . However, those skilled in the art will recognize that other types of fasteners may be used while remaining within the inventive concept. A plurality of stiffening gussets  63  may be added to the one-piece clamping member  54  to provide the requisite structural rigidity. The one-piece clamping member  54  is preferably made from sheet metal, such as stainless steel, steel, or aluminum. To install the one-piece clamping member  54  to the fuel rail  12 , the first flange portion  58  and the second flange portion  60  are biased or spread apart from each other to provide adequate clearance for the fuel rail  12  and isolating member  42  to engage the clamping portion  56 . 
     In  FIG. 4  there is shown an isolated fuel delivery system  10 C illustrating a one-piece clamping member  54 ′ which cooperates with a shim block  64  to retain the isolating member  42  and the fuel rail  12 . The one-piece clamping member  54 ′ has a clamping portion  56 ′ with a first flange portion  58 ′ and a second flange portion  60 ′ extending therefrom. The first flange portion  58 ′ has a first tab portion  65  extending therefrom at an edge farthest from the clamping portion  56 ′. Likewise, the second flange portion  60 ′ has a second tab portion  66  extending therefrom at an edge farthest from the clamping portion  56 ′. The first and second tab portions  65  and  66  engage a first ridge  68  and a second ridge  70  of the shim block  64 , respectively. In doing so, the isolating member  42  is pre-compressed by a predetermined amount prior to installation of the isolated fuel delivery system  10 C on the engine. A bore  62  is defined by the first flange portions  58 ′, second flange portions  60 ′, and the shim block  64 . The bore  62  is dimensioned to receive the hex head fastener  50 , which operates to removably attach the isolated fuel delivery system  10 C to the cylinder head  18 . The shim block  64  ensures that the isolating member  42  does not become over compressed if the specified torque on the fastener  50  is exceeded. The one-piece clamping member  54 ′ is preferably made from sheet metal, such as stainless steel, steel, or aluminum. The shim block  64  may be formed from powdered metal, aluminum, composites, etc. 
     The isolated fuel delivery systems  10  (shown in  FIG. 1   a  and  1   b ),  10 A (shown in  FIG. 2 ),  10 B (shown in  FIG. 3 ), and  10 C (shown in  FIG. 4 ) each provide a slight amount of movement to allow radial and axial positioning of the fuel rail  12  within the clamp assemblies  16 ,  16 ′ and one-piece clamping members  54 ,  54 ′. Thus, allowing greater tolerance to build variations when positioning the fuel injector  14 . The clamp assemblies  16 ,  16 ′ and one-piece clamping members  54 ,  54 ′ may extend substantially the length of the fuel rail  12  or any portion thereof. By increasing the area of the isolating member  42 , the reaction forces may be distributed over a greater area, thereby decreasing the pressure acting on the isolating member  42 . 
       FIG. 5  illustrates an isolated fuel delivery system  10 D. A fuel rail  12 ′ has a mounting boss portion  72  that defines a bore  74 . At opposite axial ends of the mounting boss portion  72  there is disposed a first isolating member  76  and a second isolating member  78 . A crush sleeve  80  has a washer portion  81  and a sleeve portion  82  extending axially therefrom. The sleeve portion  82  extends though the first isolating member  76  and at least partially into the bore  74  defined by the mounting boss portion  72 . A crush sleeve  80 ′ has a washer portion  81 ′ and a sleeve portion  82 ′ extending axially therefrom. The sleeve portion  82 ′ extends though the second isolating member  78  and at least partially into the bore  74  defined by the mounting boss portion  72 . The sleeve portions  82 ,  82 ′ and the washer portions  81  and  81 ′ may be integral, i.e. one-piece designs, or separate pieces. The fastener  50  operates to removably attach the isolated fuel delivery system  10 D to the cylinder head  18 . The axial height of length of the crush sleeve portions  82  and  82 ′ determine the preload or compression limit on the first and second isolating members  76  and  78  when the fastener  50  is torqued. The crush sleeves  80  and  80 ′ provide a measure of protection against over compression of the first and second isolating members  76  and  78  should the fastener  50  be over torqued. 
       FIG. 6   a  is a partial isometric view of the isolating member  42  mounted with respect to the fuel rail  12 . The isolating member  42  has a plurality of annularly extending grooves  86  and a plurality of axially extending grooves  88  provided on one or both of a first face  90  and a second face  92  of the isolating member  42 . The grooves  86  and  88  provide a volume or void within which the material comprising the isolating member  42  may move when compressed. Those skilled in the art will recognized that the grooves  86  and  88  may be configured in a variety of ways while still remaining within the scope of that which is claimed.  FIG. 6   b  is a plan view of the isolating ring member  32 , shown in  FIGS. 1   a  and  2 . A plurality of radially extending grooves  94  are provided on a first face  96  of the isolating ring member  32 . Likewise, a plurality of radially extending grooves  98 , shown in phantom, is provided on a second face  100  of the isolating ring member  32 . The grooves  94  and  98  provide a volume or void within which the material comprising the isolating member  42  may move when compressed. Preferably, the respective radial centerlines of the grooves  94  and  98  will not coincide. Those skilled in the art will recognized that the grooves  94  and  98  may be configured in a variety of ways, such as annular oriented grooves, while still remaining within the scope of that which is claimed. 
     The isolated fuel delivery systems  10  (shown in  FIG. 1   a  and  1   b ),  10 A (shown in  FIG. 2 ),  10 B (shown in  FIG. 3 ), and  10 C (shown in  FIG. 4) and 10D  (shown in  FIG. 5 ) provide a measure of thermal insulation since conductivity is minimized through the use of isolator members. This is beneficial to reduce heating of the fuel within the fuel system of the vehicle. 
     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.