Patent Publication Number: US-6708672-B1

Title: Fixing device for an injection nozzle

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This application claims the priority of German application 199 49 080.5, filed in Germany on Oct. 12, 1999, the disclosure of which is expressly incorporated by reference herein. 
     The invention relates to a fixing device for an injection nozzle, in particular, for internal combustion engines with direct fuel injection. The injection nozzle is of the type having a nozzle holder body whose cylindrical first and second end pieces interact with a first and a second bore hole which are worked into the components of the internal combustion engine. 
     A known injection nozzle, DE 44 18 001 A1, is set between a curved suction pipe and a flange connected to a cylinder head. Here, the injection nozzle is connected to the cylinder head as a pre-assembled unit. 
     In DE 28 29 057 A1 (corresponding to U.S. Pat. No. 4,295,452), injection valves are treated and inserted, on the one hand, into a suction equipment with the first end pieces, and on the other hand, by way of screws, connected to a fuel distributing pipe with the second end pieces. 
     One goal of the invention is to create a fixing device for an injection nozzle, which on the one hand, is leakproof even at relatively high injection pressures, and on the other, is easy to mount. 
     According to the invention, at least this goal is solved by incorporating a clamping device which acts upon a nozzle holder body of the injection nozzle, the clamping device keeping in place a first end piece of the nozle holder in a first bore hole of a cylinder head of the internal combustion engine with a defined prestress that acts in an axial direction of the injection nozzle, against which a second end piece of the nozzle holder, preferably with the help of a reduction sleeve, works together with the second bore hole of an intake arrangement. 
     The advantages of the invention that are mainly achieved are seen in the clamping device that keeps the injection nozzle in place with a defined prestress acting in an axial direction, on account of which the system pressure is taken into account, particularly in direct fuel injection for internal combustion engines of the Otto design, and special screws for each injection nozzle can be eliminated. The reduction sleeve also ensures that the manufacturing tolerances that constantly appear are not damaging to the connecting function of the injection nozzle. With the metallic clamping sleeve, which is easy to produce, a targeted prestress, aimed towards the cylinder head, can be effected also, thanks to the shock absorber. It is also possible for the reduction sleeve to be pre-assembled in a simple manner through the inward formations and the recesses between the clamping sleeve and reduction sleeve or the extension of the clamping sleeve and the wall section of the suction pipe equipment. The assembly of the injection nozzle itself is only a simple introductory process. 
    
    
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cross sectional view of a cylinder head of an internal combustion engine with the fixing device according to the invention for an injection nozzle; 
     FIG. 2 is a perspective view showing a detail of FIG. 1 in a larger scale; 
     FIG. 3 is a view corresponding to FIG. 2 with another form of embodiment; and 
     FIG. 4 is a view of a detail of FIG. 3 in a larger scale. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     A multicylinder internal combustion engine  1  of the Otto design, not presented in greater detail, comprises, for instance, of a cylinder head  2  and an intake arrangement  3 . The intake arrangement  3  is connected to the cylinder head  2 , for which purpose the cylinder head  2  is provided with a first contact surface  4  and the intake arrangement  3  with a second contact surface  5 . By means of the intake arrangement  3 , fresh air is fed to a combustion chamber  8  through a conduit  7  provided with a butterfly valve  6 . In this combustion chamber  8 , motor fuel, i.e., gasoline, is fed using an injection nozzle  9 , which means that the internal combustion engine works with direct fuel injection. In the cylinder head  2 , intake and exhaust valves, which are not shown, are effective for gas-changing control-fresh air/waste gas. 
     For the injection nozzle  9 , a fixing device  10  is provided, with the injection nozzle  9  exhibiting a nozzle holder body  11  with a first end piece  12  and a second end piece  13 . The nozzle holder body  11  and the end pieces  12  and  13  exhibit a cylindrical configuration with a circular cross-section. The end pieces  12  and  13  interact with a first bore hole  14  and a second bore hole  15 , which are worked into the components of the internal combustion engine  1 . These components are formed by the cylinder head  2  and the intake arrangement  3 . 
     A clamping device  16  acts upon the nozzle holder body  11  of the injection nozzle  9 , which clamping device  16  holds—with a defined prestress that acts in an axial direction A—the first end piece  12  in the first bore hole  14  in the cylinder head  2 . In comparison, the second end piece works together with the second bore hole  15  in the intake arrangement  2  through the intermediary of a reduction sleeve  17 . The clamping device  16  acts upon a radial catch  18  of the nozzle holder body  11 . To this end, the clamping device  16  is provided with a bifurcated clamping section  19 , which is adjacent to the catch  18 . The clamping section  19  of the clamping device  16  is a component of a plate-like support  20 , which is clamped between the first contact surface  4  of the cylinder head  2  and the second contact surface  5  of the intake arrangement  3  and is held in place. 
     According to FIG. 3, the clamping device is a clamping sleeve  21 , which coaxially, and like a casing, surrounds the nozzle holder body  11  of the injection nozzle  9  in a partial area  22 ; another partial area  23  of the nozzle holder body  11  is exposed. The clamping sleeve  21  is propped, on the one hand, on a buffer  50  of the nozzle holder body  11 , and on the other hand, on a support plane  52  of the intake arrangement  3 . The clamping sleeve  21  consists of a suitable metal with spring characteristics. Manufacturing the clamping sleeve  21  from an appropriate synthetic material is also conceivable. To obtain a targeted clamp force, the clamping sleeve  21  encircles sector by sector a bellows-like spring section  24 , which is provided next to the support plane  3  of the intake arrangement  3 . 
     According to FIG. 4, in the area of the reduction sleeve  17 , the clamping sleeve  21  exhibits an inward formation  25 , which flexibly engages in a groove-like recess  26  of the said reduction sleeve  17 . As a result, the inward formation  25  and the recess  26  work together in a form- and force-locking manner. Moreover, the clamping sleeve  21  is provided with an extension  27  that overlaps a wall section  28  of the intake arrangement  3  and rests against this wall section while under spring tension. The extension  27  has an inward formation  29 , which engages in an outward formation  30  of the wall section  28 , as a result of which the inward formation  29  and the outward formation  30  work together in a form-locking manner. 
     The intake arrangement  3  is provided with a fuel supply conduit  31  next to the reduction sleeve  17 , said fuel supply conduit being made of one piece with the intake arrangement  3 . From a cross-sectional view, the fuel supply conduit  31  exhibits an oval shape with side walls  32 ,  33 , which are aligned in more or less longitudinal direction B—B of the conduit  7  or of a medium length plane of the latter. 
     An end piece  34 , which rests in the second bore hole  15  of the intake arrangement  3 , and is turned towards the intake arrangement  3 , is provided on the reduction sleeve  17 . The end piece  34  is provided on its exterior  35  with a recess  36 , which is developed as a receptacle for a first sealing  37 . The sealing  37  is effective between borehole  15  and reduction sleeve  17  or recess  36 . A comparable execution is arranged on the second end piece  13  of the nozzle holder body  11 . The second end piece  13  rests in a bore hole  38  of the reduction sleeve  17  and it exhibits a recess  40  that serves as a receptacle for a second sealing  39 . The sealing  39  is operative between the borehole  38  and the end piece  13  or of the recess  40 . 
     The injection nozzle  9  is consequently stored on the side of the intake arrangement  3  in such a way that it compensates for tolerance. In comparison, the injection nozzle  9  is set position-wise on the side of the cylinder head  2  by means of conical surfaces  41 , in the course of which the injection nozzle  9 , at a distance to the conical surfaces  41 , is provided with a radial stopping face  42 , which is propped on a corresponding stopping surface  44  of the cylinder head  2 , by means of a sealing body  43 . 
     The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.