Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based on German Patent Application 10 2005 029 842.7 filed Jun. 27, 2005, upon which priority is claimed.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates to an improved fuel reservoir of a fuel injection system of a motor vehicle.  
         [0004]     2. Description of the Prior Art  
         [0005]     One fuel reservoir of the type with which this invention is concerned can for instance be part of a common rail diesel injection system or part of a direct gasoline injection system and is also known by the name of “rail”. A known rail has one or more fastening portions, with which it can be fastened to the internal combustion engine. The connecting elements are formed by screws, which are screwed into the housing of an engine and tightly fasten the fastening portion between the head of the screw and the shaft that is screwed into the engine housing.  
         [0006]     The rail is in communication with fuel injection devices, or injectors which can inject fuel into a combustion chamber of the engine. The injectors are fastened to the engine and can be supplied with fuel from the rail via lines.  
         [0007]     From German Patent Disclosure DE 195 46 441 A1, an arrangement comprising a rail and injector is known, in which the injector is received directly in the rail, without using an additional line.  
       OBJECT AND SUMMARY OF THE INVENTION  
       [0008]     With this as the point of the departure, it is the object of the present invention to make a fuel reservoir available that can be produced inexpensively and can be secured to the engine and removed from it equally simply and securely.  
         [0009]     It has been found according to the invention that after a relatively long time of engine operation, the rail and/or the fuel injection devices can become stuck to the engine at their contact faces or in their contact regions. For releasing the rail and/or the fuel injection devices from the engine, comparatively strong loosening forces may then be required. At the same time, however, care must be taken to handle the individual components as gently as possible in the process of removing the fuel reservoir and/or the fuel injection devices from the engine.  
         [0010]     The connecting element of the fuel reservoir of the invention has a dual function. First, with a first bearing face, the connecting element can firmly tighten the fastening portion of the fuel reservoir to the engine. This first bearing face accordingly acts in the tightening direction. Second, with its second bearing face, the connecting element can function as a removal tool and upon the release of the connecting element can, with this second bearing face, lift the fastening portion off or press it away from the engine. Hence the second bearing face acts counter to the first bearing face.  
         [0011]     As a result, one additional special tool can be dispensed with, which reduces the costs for dismantling a rail. At the same time, even with a rail that is “baked hard” onto the engine, simple and reliable dismantling is made possible, without necessitating manual forces that are difficult to adjust. Especially if the injectors are secured directly and rigidly to the rail, damage both to the injectors and to contact faces that are present on the engine are thus avoided.  
         [0012]     It is understood that the bearing face need not necessary be designed to be flat and to rest completely on the fastening portion. Still other versions are possible that have only a linear or point-type contact. The only important factor is that the connecting element on the fastening portion be capable of acting in two opposed directions.  
         [0013]     The bearing faces are advantageously oriented toward one another, so that depending on the joining direction of the connecting element, the fuel reservoir can selectively either be urged toward or firmly tightened onto the engine, or pulled off or forced away from the engine.  
         [0014]     In a feature of the invention, the connecting element has a head region for forming a first bearing face and a shaft region with a radially widened portion for forming a second bearing face. Thus the connecting element can rest with its head region on a first contact face of the fastening portion and can firmly tighten the fastening portion of the fuel reservoir to the engine. With its radially widened portion, the connecting element can form a removal tool. When the fuel reservoir is removed from the engine, the radially widened portion presses against a second contact face of the fastening portion. There is no need to use further tools, and especially expensive special tools.  
         [0015]     By means of the fuel reservoir according to the invention, the loosening forces required for removing the fuel reservoir from the engine can be introduced gently, so that the fuel reservoir can be carefully detached from the engine. Especially if the fuel reservoir communicates with a fuel injection device, strong dismantling forces can be built up in a gentle way, to enable loosening the fuel injection device from its firm seat in the housing of the engine.  
         [0016]     Introducing loosening forces gently and uniformly over the length of the fuel reservoir is possible especially if a plurality of connecting elements are provided, which are preferably distributed uniformly on the fuel reservoir, so that the loosening forces can be introduced in a plurality of regions and in a uniformly distributed way.  
         [0017]     In a feature of the invention, the fastening portion is embodied in flangelike fashion. This makes it possible for the first and second contact faces to be located largely parallel to one another, so that introducing tightening and loosening forces can be done without the connecting element becoming tilted or without the introduction of bending forces.  
         [0018]     The fastening portion may have grooves, slits, and/or circumferentially closed through openings for the disposition of the connecting element. The width of the groove or slit or the height of the through opening corresponds in the simplest case to the thickness of the material comprising the fastening portion. The grooves or through openings make it possible to secure the fuel reservoir to the engine in a simple way, with the aid of the connecting element.  
         [0019]     In a feature of the invention, the radially widened portion is formed by an annular collar which is nondetachably connected and in particular integrally connected to the connecting element. This annular collar can be produced for instance by suitable cold or hot shaping of a screw blank, or by welding on or press-fitting on of an annular disk.  
         [0020]     It is also possible for the radially widened portion to be embodied as a separate element secured to the shaft region, so that a relative motion, above all in the axial direction, between the radially widened portion and the shaft region can be precluded. In such a case, the radial region can be formed for instance by a disk that is press-fitted on or by a self-locking nut that is screwed onto the shaft region.  
         [0021]     An advantageous feature of the invention provides that the fastening portion, adjacent to the second contact face, has a receptacle chamber in which the radially widened portion is received at least in some portions, and in particular entirely. This has the advantage that the housing of the engine need not be adapted, since the radially widened portion can be received in the fastening portion.  
         [0022]     It is also possible that the housing of the engine has an indentation, in which the radially widened portion is received at least in some portions, and in particular entirely. This version has the advantage that the fastening portion can be made especially low in height, which is advantageous for instance when the installation space in the engine compartment of a motor vehicle is tight.  
         [0023]     These advantages become especially important when the fuel reservoir is solidly connected to at least one fuel injection device. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings, in which:  
         [0025]      FIG. 1  is a schematic illustration of a fuel injection system having a fuel reservoir and an internal combustion engine;  
         [0026]      FIG. 2  is a sectional view of the fastening of the fuel reservoir to the engine in the prior art;  
         [0027]      FIG. 3  is a sectional view of a fuel reservoir of the invention is a first embodiment;  
         [0028]      FIG. 4  is a top view on a fuel reservoir in a second embodiment; and  
         [0029]      FIG. 5  is a sectional view of the fuel reservoir of  FIG. 4 , taken along the line V-V in  FIG. 4 .  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]     In  FIG. 1 , a fuel injection system is identified in its entirety by reference numeral  10 . From a fuel collection container  12 , the fuel reaches a high-pressure pump  14  and from there a fuel reservoir  16 . The fuel reservoir  16  communicates with fuel injection devices  18 , of which only one of many fuel injection devices  18  is shown in  FIG. 1 . The fuel injection device  18  is supplied with fuel through the fuel reservoir  16  and injects the fuel into a combustion chamber  20 , shown schematically, of an internal combustion engine  22 , also only partly shown.  
         [0031]     The fastening of the fuel reservoir  16  to the engine  22  of the prior art will be described in conjunction with  FIGS. 2 through 4 . In  FIG. 2 , a fuel reservoir  16  and an engine  22  of the prior art are shown in section. In the engine  22 , a graduated installation space  24  is provided, in which the fuel injection device  18  is received. The fuel injection device protrudes with a nozzle  26  into the combustion chamber  20 . On the end diametrically opposite the nozzle  26 , the injector head  28  of the fuel injection device  18  is received in a high-pressure chamber  30  embodied in the fuel reservoir  16 . The injector head  28  is sealed off from the high-pressure chamber  30  with the aid of a seal  32 .  
         [0032]     The fuel injection device  18  is solidly connected to the fuel reservoir  16  with the aid of a clamp  34 .  
         [0033]     The fuel reservoir  16  has a tubular storage chamber  36 , which communicates with the high-pressure chamber  30  via a bore  38 .  
         [0034]     Laterally adjacent to the storage chamber  36 , the fuel reservoir  16  has two flangelike fastening portions  40  and  42 . Through openings  44  and  46  are embodied in flange portions  40 ,  42  and connecting elements  48  and  50  reach through these through openings. The connecting elements  48  and  50  have head regions  52  and  54  and shaft regions  56  and  58 , respectively. The connecting elements  48  and  50 , in their respective shaft regions  56  and  58 , are each provided with a male thread (not identified by reference numeral), to enable them to be inserted into corresponding threaded receptacles  60  and  62  embodied in the engine.  
         [0035]     The fastening portions  40  and  42  have first contact faces  64  and  66 , respectively, facing toward the head regions  52  and  54  of the connecting elements  48  and  50 . As a result of the contact of the head regions  52  and  54  with the first contact faces  64  and  66 , the fuel reservoir  16  can be firmly tightened to the engine  22 .  
         [0036]     In  FIG. 3 , the arrangement of  FIG. 2  is shown, modified according to the invention. The connecting element  48 ′ shown in  FIG. 3 , like the connecting element  48  shown in  FIG. 2 , also has a head region  52  and a shaft region  56 . On the side toward the engine  22 , the head region  52  has a first bearing face  65 , which is intended for resting on the first contact face  64  of the fastening portion  40 ′. The shaft region  56  is provided with a male thread  68 , which is suitable for engagement with the receptacle  60  embodied in the engine  22 .  
         [0037]     On the shaft region  56  of the connecting element  48 ′, a radially widened portion  70  is provided, in the form of an annular collar nondetachably joined to or integrally formed onto the connecting element  48 ′. The annular collar has an outer diameter that is greater than the diameter of the through opening  44  embodied in the fastening portion  40 ′. The radially widened portion  70  is received entirely in a receptacle chamber  72  embodied in the fastening portion  40 ′. The radially widened portion  70  forms an annular second bearing face  74 , facing toward the head region  52  and the first bearing face  65 .  
         [0038]     The face  74  is provided to cooperate with a second contact face  76 , embodied on the fastening portion  40 ′, in the following way: If the connecting element  48 ′ is moved out of the engine  22 , by being rotated out of the receptacle  70  in the dismantling direction  78 , the second bearing face  74  comes into contact with the second contact face  76 , so that the fuel reservoir  16  is forced away from the engine  22 . As a result of the loosening forces thus generated, a fuel injection device  18 , which communicates with the fuel reservoir  16  (see  FIG. 2 ), can simultaneously be pulled out of the engine  22 .  
         [0039]      FIG. 4  shows a further fuel reservoir  16 ″ with two fastening portions  40 ″ and  42 ′ in a top view. The peripheral region of each of the fastening portions  40 ″ and  42 ′ is provided with a respective slitlike groove  80  and  82 . The fuel reservoir  16 ″ can be connected to an engine  22 ′ as shown in  FIG. 5 . Also in  FIG. 5 , a connecting element  48 ″ is shown, with which the fastening portion  40 ″ is secured to the engine  22 ′.  
         [0040]     The connecting element  48 ″ has a head region  52 ′ and a shaft region  56 ′. An annular first bearing face  65 ′ is located on the head region  52 ′. On the shaft region  56 ′, a radially widened portion  70 ′ is provided, which forms an annular second bearing face  74 ′, facing toward the head region  52 ′. The radially widened portion  70 ′ is received entirely in an indentation  84  embodied in the engine.  
         [0041]     The fastening portion  40 ″ has a first contact face  64 ′, facing toward the head region  52 ′. The second contact face  76 ′ is located on the diametrically opposite side of the fastening portion  40 ′ and is in contact with the housing of the engine  22 ′. In the installed state of the fuel reservoir  16 ″, the head region  52 ′presses with its first bearing face  65 ′ against the first contact face  64 ′, so that the fastening portion  40 ′ is pressed against the engine  22 ′. Upon removal of the connecting element  48 ″ in the dismantling direction indicated by an arrow  78 , the second bearing face  74 ′ of the radially widened portion  70 ′ comes into contact with the second contact face  76 ′ of the fastening portion  40 ″, so that the fuel reservoir  16 ″ is forced away from the engine  22 ′.  
         [0042]     The foregoing relates to preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.

Technology Category: 2