Patent Publication Number: US-2007113828-A1

Title: Fuel injector isolating and sealing member

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims priority to U.S. Provisional Application No. 60/738,798 filed on Nov. 22, 2005. 
    
    
     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, at a predetermined time, 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 may enable higher peak power levels, improved fuel economy, and lower exhaust emissions. These beneficial aspects of the DI fuel delivery system are a result of precise metering of the fuel injected into the combustion chamber as well as improved intake airflow into the combustion chamber.  
      The 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-producing vibrations. The transmission of the vibrational energy generated within the DI fuel delivery system to the engine structure may follow at least two paths, such as; 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  
      A fuel injector isolating and sealing member is provided for sealing and isolation of a fuel injector, such as a direct injection fuel injector. The isolating and sealing member includes a core portion having a sleeve portion defining a bore sufficiently configured to receive at least a portion of the fuel injector. A flange portion extends radially inwardly from the core portion and is sufficiently configured to bias the fuel injector within the bore. At least one of the core portion and the flange portion has at least one of an outer isolating and sealing layer and an inner isolating and sealing layer.  
      The sleeve portion may be generally cylindrical and the flange portion may have an axial offset operable to bias the fuel injector within the bore. Additionally, at least one of the inner and the outer isolating and sealing layers may be formed from one of a fluorocarbon elastomeric polymer material and a viscoelastic material, while the core portion may be formed from stainless steel. The fuel injector isolating and sealing member in combination with the fuel injector may be configured to be at least partially received within a cylinder head of an internal combustion engine. A fuel system and an internal combustion engine incorporating the disclosed fuel injection isolating and sealing member is also provided.  
      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  is a schematic sectional perspective view of a portion of an internal combustion engine illustrating a fuel delivery system consistent with the present invention;  
       FIG. 2  is a cut-away perspective view of a fuel injector isolating and sealing member; and  
       FIG. 2   a  is a cross-sectional view of the fuel injector isolating and sealing member taken along line A-A of  FIG. 2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to the figures wherein like reference numbers refer to like or similar components, there is shown in  FIG. 1 a  portion of an internal combustion engine, generally indicated at  10 . The internal combustion engine  10  includes a cylinder case  12 , cylinder head  14 , and a fuel injection system  16 . The cylinder case  12  defines a cylinder bore  18  within which a piston  19  is reciprocally movable. Although only one cylinder bore  18  is shown in  FIG. 1 , it should be apparent to those skilled in the art that the aspects taught by the present invention may be applied to engines having a plurality of cylinders bores  18  such as 4, 6, 8, 10, 12 and 16 cylinder engines. The cylinder head  14  is removably mounted with respect to the cylinder case  12 , and cooperates with the cylinder bore  18  and the piston  19  to form variable volume combustion chamber  20 . The internal combustion engine  10  shown in  FIG. 1  is a direct injected, or DI, engine in that the fuel to be combusted is injected directly into the combustion chamber  20  by the fuel injection system  16 .  
      The fuel injection system  16 , in the preferred embodiment, includes a direct injection fuel injector  22 , a fuel injector isolating and sealing member  23 , a fuel rail  24 , and an electronic control unit  26 . The electronic control unit  26  includes a pre-programmable digital computer and operates to provide control signals to the fuel injector  22 , thereby commanding the fuel injector  22  to deliver a predetermined amount of fuel at a specific point in the engine cycle. The fuel rail  24  acts as a conduit or manifold to deliver pressurized fuel to the fuel injector  22 . The fuel rail  24  includes a mounting boss  28  sufficiently configured to receive one end of the fuel injector  22  and retain the fuel injector  22  in relation to the fuel rail  24 . The fuel rail  24  in the preferred embodiment removably mounts the fuel injector  22  with respect to the cylinder head  14 . The fuel injector  22  further includes a body or housing portion  30  having a tip portion  32  extending axially therefrom. The fuel injector isolating and sealing member  23  includes a generally cylindrical sleeve portion  34  having a flange portion  36  extending generally radially inwardly therefrom. The sleeve portion  34  defines a bore  38  sufficiently configured to receive the body portion  30  of the fuel injector  22 , such that a radially inwardly extending surface  40  of the body portion  30  abuts the flange portion  36 . The flange portion  36  is axially offset toward the bore  38 .  
      The cylinder head  14  defines a stepped bore  42 . The stepped bore  42  includes a generally cylindrical first bore portion  44  and a generally cylindrical second bore portion  46  coaxially disposed with respect to the first bore portion  44 . A circumferential land  48  is provided intermediate the first and second bore portions  44  and  46 . The stepped bore  42  is sufficiently configured to receive the fuel injector  22 . More specifically, the first bore portion  44  is sufficiently configured such that the tip portion  32  can pass through the cylinder head  14  to communicate with the combustion chamber  20 . Additionally, the second bore portion  46  is sufficiently configured to receive the body portion  30  of the fuel injector  22  with the fuel injector isolating and sealing member  23  mounted thereto. The circumferential land  48  operates as a means to locate the fuel injector  22  within the cylinder head  14 . The axial offset nature of the flange portion  36  serves to bias the fuel injector  22 , within the stepped bore  42 , away from the circumferential land  48 , and in so doing, provide a measure of compliance between the fuel injector  22  and the head  14 . An annular combustion seal  50  is provided about the tip portion  32  to sealingly engage the first bore portion  44  to disallow pressurized gases within the combustion chamber  20  from traversing the stepped bore  42 .  
      Referring to  FIG. 2 , and with further reference to  FIG. 1 , the structure of the fuel injector isolating and sealing member  23  will be described in greater detail. The fuel injector isolating and sealing member  23  includes a core portion  52  having an outer isolating and sealing layer  54  and an inner isolating and sealing layer  56  attached thereto. In the preferred embodiment, the inner and outer isolating and sealing layers  54  and  56  will be formed from a material with sufficient resistance to heat, abrasion, and fuel such as, for example, a fluorocarbon elastomeric polymer compound. However, those skilled in the art will recognize that other materials may be suitable for use, such as certain viscoelastic materials, while remaining within the scope of that which is claimed. The core portion  52  is preferably formed from stainless steel or any material with sufficient structural rigidity to resist significant deformation due to the insertion of the fuel injector  22  or the insertion of the fuel injector isolating and sealing member  23  into the cylinder head  14 . Additionally, the material comprising the core portion  52  should be of sufficient stiffness to provide the necessary force to bias fuel injector  22  away from the circumferential land  48  during operation of the fuel injector  22 . The core portion  52  should also be formed from a material having the sufficient stiffness to counteract the motion of the fuel injector  22  in a fully isolated fuel delivery system. Those skilled in the art will recognize that the core portion  52  may be formed from other materials such as aluminum, stainless steel, composites, etc. while remaining within the scope of that which is claimed.  
       FIG. 2   a  is a true cross sectional view of the fuel injector isolating and sealing member  23  taken along line A-A of  FIG. 2 . Those skilled in the art will recognize that the relative thicknesses of the core portion  52  and the inner and outer isolating and sealing layers  54  and  56  will depend on the application and the materials utilized therein. Additionally,  FIG. 2   a  illustrates a generally annular first sealing portion  58  that operates to seal the fuel injector  22  to the fuel injector isolating and sealing member  23 , and a generally annular second sealing portion  60  that operates to seal the fuel injector isolating and sealing member  23  to the cylinder head  14 .  
      During operation of the internal combustion engine  10 , it is desirable to disallow gases within the combustion chamber  20  from traversing the stepped bore  42 . As state earlier, the combustion seal  50  operates to seal the stepped bore  42  from the combustion chamber  20 . Additionally, a carbon dam may develop near the combustion seal  50  as a result of combustion of fuel within the combustion chamber  20 . This carbon dam further blocks any egress of gases into the stepped bore  42 . The combustion seal  50  and the carbon dam, although generally effective, may not totally seal the stepped bore  42  from combustion gases under certain engine operating conditions. Additionally, although the combustion seal  50  may be effective in static or non-isolated fuel delivery systems, the durability and sealing effectiveness of the combustion seal  50  may be reduced in a fully isolated fuel delivery system. As such, the fuel injector isolating and sealing member  23  and more specifically the first and second sealing portions  58  and  60  operate to further seal the stepped bore  42  from gases within the combustion chamber  20 . This is especially beneficial for evaporative emission purposes.  
      The on/off or pulsating nature of the fuel injector  22 , combined with the high fuel pressure present within the fuel rail  24  required to directly inject fuel into the combustion chamber  20  during operation of the engine  10 , may transmit objectionable noise producing vibrations from the fuel injector  22  to the cylinder head  14  and other components of the engine  10 . The fuel injector isolating and sealing member  23  operates to isolate these vibrations. The offset nature of the flange portion  36  adds compliance to the fuel injection system  16  by operating in a spring-like fashion similar to a conical spring. By biasing the fuel injector  22  away from the circumferential land  48 , the fuel injector  22  will be less likely to ground to the cylinder head  14  thereby isolating the fuel injector  22  from the cylinder head  14 . Additionally, the inner and outer isolating and sealing layers  54  and  56  provide a measure of isolation and vibration absorption to the fuel injector  22 . The fuel injector isolating and sealing member  23  may also provide a measure of thermal insulation, such that heat energy from the cylinder head is less likely to be transmitted to the fuel within the fuel injector  22  and the fuel injection system  16 .  
      The fuel injector isolating and sealing member  23  of the present invention may be installed within the fuel injection system  16  with little or no modification to the existing parts. Although the fuel injector isolating and sealing member  23  described in the preferred embodiment is generally cylindrical in nature, those skilled in the art will recognize that the fuel injector isolating and sealing member  23  may formed in other shapes while remaining within the scope of that which is claimed.  
      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.