Patent Publication Number: US-10316809-B2

Title: Fuel injection system for an internal combustion engine

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is claims priority under 35 U.S.C. § 119 from German Patent Application No. 10 2016 009 079.0, filed Jul. 27, 2016, the entire disclosure of which is herein expressly incorporated by reference. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to a fuel injection system for an internal combustion engine, comprising at least one fuel injection nozzle. 
     A device is known, from JPH03182680 A, in which a fuel injection nozzle of an internal combustion engine is arranged in a bore of a cylinder head. The device has a holding device which is designed in the manner of a two-arm lever and which engages at one side with a first arm on a collar-like stop of the fuel injection nozzle and at the other side with a second arm on a bolt head of a cylinder head bolt. A fastening bolt extends between the two arms, which fastening bolt is screwed into a thread in the cylinder head and braces the fuel injection nozzle against a stop in the bore of the cylinder head with the interposition of a seal. Furthermore, a nozzle tip of the fuel injection valve extends through a passage opening in the cylinder head and is thereby connected to a combustion chamber of the internal combustion engine. 
     DE 195 54 065 A1 discloses an assembly for fastening an injection nozzle in a holder which is equipped with a receiving opening for the injection nozzle. A bracing element is attached to the injection nozzle. By means of fastening bolts, the bracing element is connected to the holder, specifically such that the injection nozzle bears with a force fit against a stop in the receiving opening. A sealing disk is installed between the injection nozzle and stop. Also, a nozzle tip of the injection nozzle extends through a passage bore in the holder, such that fuel can be introduced into a downstream combustion chamber. 
     It is an object of the invention, for a fuel injection nozzle of a fuel injection system which operates in an internal combustion engine, to devise measures which firstly hold the fuel injection nozzle securely in position on the internal combustion engine and which secondly promote simple installation of said fuel injection nozzle. Here, it should however also be sought to achieve that the measures can be implemented with means which substantially involve little outlay. 
     According to the invention, said object is achieved by a fuel injection system for an internal combustion engine, comprising at least one fuel injection nozzle which, by way of a cylindrical shell body, is inserted at least in regions into a bore of a cylinder head and which, by way of a nozzle tip, feeds fuel to a combustion chamber between the cylinder head and a reciprocating piston. The fuel injection nozzle is held in position on a housing section of the internal combustion engine with the interposition of a holding device, which holding device braces a first end region of the fuel injection nozzle against a bore stop within the bore in the cylinder head. The holding device has, outside the bore, a fixing bushing to which the shell body is fixed axially and radially by way of a radial insert element. A spring system acts between a first radial stop of the fuel injection nozzle and a second radial stop of the fixing bushing as viewed in the axial direction of the shell body of the fuel injection nozzle. The spring system seeks to move the fixing bushing, by way of a third radial stop, against a locking element system of the insert element, which is supported on a fourth radial stop applied to the shell body. 
     The main advantages achieved by the invention can be seen in that it is exemplary from a design aspect that the holding device of the fuel injection nozzle has, outside the bore in the cylinder head, the fixing bushing to which the shell body of the injection valve is fixed axially and radially by the radial insert element. Here, the spring system acts between the first radial stop of the fuel injection nozzle and the radial stop of the fixing bushing as viewed in the axial direction of the shell body. The spring system seeks to move the fixing bushing, by way of a third radial stop, against the locking element system of the insert element, which is supported on the fourth radial stop applied to the shell body. 
     It is exemplary that the insert element is in the form of a U-shaped fixing clip which is made up of two parallel limbs and a transverse web which connects said limbs, the limbs of the first and second locking elements and the transverse web forming the third locking element. In this regard, it is to be emphasized that at least the first and second locking elements have a square cross section. It is expedient from a structural aspect that the first and second locking elements have inner delimitations and outer delimitations as viewed in the radial direction of the metal body of the fuel injection nozzle. The inner delimitations interact with first flattened portions of the metal body and the outer delimitations interact with second flattened portions of the fixing bushing. For optimization of the fixing clip, it is also conducive that its transverse web is, as viewed in the radial direction of the shell body, fixed by an axial securing collar of the fixing bushing. 
     With regard to the spring system, standards are set by the fact that it is formed in a ring-shaped manner between the first stop of the shell body and the second stop of the fixing bushing. This is achieved in that the spring system is formed by a spring device composed of rubber or elastomer and a compression spring composed of spring steel, which spring device and compression spring are situated one behind the other as viewed in the axial direction, the compression spring being supported against the first stop and the spring device being supported against the second stop. It is also of note that the spring device is of double-T-shaped form in cross section and, by way of the limbs connected to the transverse web, acts as a sealing body between the first flattened portions of the shell body and the second flattened portions. 
     A design which is sophisticated from a strength aspect can be realized in that the fixing bushing is, in the direction of the second end region of the fuel injection nozzle, equipped with a jacket cup which has a first, conical shell section leading away from the fixing bushing, with a second, cylindrical shell section adjoining said first shell section. Furthermore, the second shell section is neatly delimited by the support flange. 
     An excellent design is realized in that the fixing bushing, the first shell section and the second shell section are combined as a high-strength bearing bracket produced in one piece. A further possible use of the bearing bracket is made possible by virtue of the bearing bracket being designed for receiving two fuel injection nozzles, wherein a single fastening bolt which extends, in a central longitudinal plane between the injection nozzles, through a bracket bore, which is surrounded by a turned-up reinforcement of the bearing bracket, serves for fastening the bearing bracket to the housing section of the internal combustion engine. It is also expedient that a sealing device is provided between the support flange and a contact plane of the housing section. It is groundbreaking from a manufacturing aspect that the bearing bracket, the fuel injection valves, the spring systems and the insert elements form a prefabricated structural unit. 
     Finally, for the installation of the fixing clips, which are in the form of insert elements, an ingenious method is suitable in which the spring systems and, subsequently, the fuel injection nozzles are inserted into the fixing bushings of the bearing bracket. The respective fixing clips then are subjected, via the first stop, to load in the axial direction of the fuel injection nozzle such that the insert element can be inserted radially, in such a way that the securing collar of the fixing bushing engages over the transverse web of the fixing clip such that the fixing clip is radially secured after the spring system is relieved of load. 
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a partial oblique view of an internal combustion engine with an indicated fuel injection system which has at least one fuel injection nozzle. 
         FIG. 2  shows a detail X of  FIG. 1  partially in section and on an enlarged scale with at least one insert element for axially and radially securing the fuel injection nozzle as per  FIG. 1 . 
         FIG. 3  shows a detail Y of  FIG. 2  on an enlarged scale and partially in section with the insert element. 
         FIG. 4  shows a section approximately along the line IV-IV of  FIG. 3 . 
         FIG. 5  shows an oblique view of the insert element as per  FIG. 2  on its own. 
         FIG. 6  shows a section approximately along the line VI-VI of  FIG. 3  on an enlarged scale. 
         FIG. 7  shows a first installation position of the insert element as per  FIGS. 2 and 3 . 
         FIG. 8  shows a second installation position of the insert element as per  FIGS. 2 and 3 . 
         FIG. 9  shows a view approximately in the arrow direction Z of  FIG. 1 . 
         FIG. 10  shows a section approximately along the line X-X of  FIG. 9 . 
         FIG. 11  shows a section along the line XI-XI of  FIG. 1  on an enlarged scale. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     An internal combustion engine  1 , of a reciprocating-piston type of construction, which is suitable for use in land vehicles, watercraft or the like, has a fuel injection system  2  for diesel or gasoline and is equipped with at least one fuel injection nozzle  3 . The fuel injection nozzle  3  is attached, with the interposition of a holding device  4 , to a housing section  5  of an engine housing  6  of the internal combustion engine  1 . More details regarding the internal combustion engine  1  emerge from DE 10 2012 015 907 B3, the engine housing of which likewise has a cylinder head  7  and a cylinder crankcase  8 . 
     The fuel injection nozzle  3  is equipped with a cylindrical shell body  9  which is inserted at least in regions into a bore  10  of the cylinder head  7  and, by way of a nozzle tip  11 , feeds fuel to a combustion chamber  12  between cylinder head  7  and a reciprocating piston  13 . Also, the fuel injection nozzle  3  is held on the housing section  5  of the engine housing  6  by the holding device  4  and, for example, a fastening bolt  15 . A first end region  16  of the fuel injection nozzle  3  is braced— FIG. 2 —against a bore stop  17  within the bore  10  in the cylinder head  7  by way of the holding device  4 , wherein a sealing element may be provided between bore stop  17  and first end region  16 . 
     Outside the bore  10 , there is provided on the holding device  4 — FIGS. 2 and 3 —a fixing bushing  18  which, by way of an internal bore  19 , surrounds the shell body  9 . The fuel injection nozzle  3  or the shell body  9  is fixed axially and radially to the fixing bushing  18  with the interposition of a radial—relative to the axial direction A-A of the fuel injection nozzle  2  or the shell body  9 —insert element  20 . As viewed in the axial direction A-A of the shell body  9  of the fuel injection nozzle  3 , a spring system  23  acts between a first radial stop  21  of the fuel injection nozzle  3  and a second radial stop  22  of the fixing bushing  18 . The spring system  23  seeks to move the fixing bushing  18 , by way of a third radial stop  24 , against a locking element system  25  of the insert element  20 , which is supported on a fourth radial stop  26  of the shell body  9 . The insert element  20  is in the form of a U-shaped fixing clip  27 — FIGS. 4 and 5 —which is made up of two parallel limbs  28  and  29  and of a transverse web  30  which connects the limbs. The limbs  28  and  29  form first and second locking elements  31  and  32 ; the transverse web  30  forms a third locking element  33 . The locking elements  31  and  32 , which are situated in planes B-B and C-C, are each provided with a square cross section QI and QII. By contrast, the cross section QIII of the third locking element  33  may be rectangular, and the latter surrounds the shell body  9 — FIG. 4 —in arcuate fashion. 
     The first and second locking elements  31  and  32  have inner delimitations  34  and  35  and outer delimitations  36  and  37  as viewed in a radial direction D-D of the fuel injection nozzle  2  or of the shell body  9 . The inner delimitations  34  and  35  interact with first flattened portions  38  and  39  of the shell body  9 , and the outer delimitations  36  and  37  interact with second flattened portions  40  and  41  of the fixing bushing  18 — FIG. 4 . The transverse web  30  of the fixing clip  27  is, as viewed in the radial direction D-D— FIG. 2 —of the shell body  9 , fixed by way of an axial securing collar  42 — FIG. 3 —of the fixing bushing  18  in the radial direction D-D, which securing collar  42  is applied adjacent to an outer circumference  43  of the fixing bushing  18 . 
     The spring system  23  is formed in a ring-shaped manner between the first stop  21  of the shell body  9  and the second stop  22  of the fixing bushing  18 — FIG. 6 . Also, the spring system  23  includes a spring device  44  composed of rubber, elastomer or the like and a compression spring  45  composed of spring steel, which spring device and compression spring abut against one another in a radial plane F-F. The compression spring  45  is supported on the first stop  21 ; the spring device  44  is supported on the second stop  22 . The spring device  44  is of double-T-shaped form in cross section and acts as a sealing body  46 , and by way of limbs SchI and SchII connected by a transverse web Qs, between the first flattened portions  38  and  39  of the shell body  9  and the second flattened portions  40  and  41 — FIGS. 4 and 6 . 
     The fixing bushing  18  is, in the direction of a second end region  47  of the fuel injection nozzle  3 , equipped with a jacket cup  48 . The latter has a first, conical shell section  49  which leads away from the fixing bushing  18  and which widens proceeding from the fixing bushing  18 , wherein said first shell section is adjoined by a second, cylindrical shell section  50 . The second, cylindrical shell section  50  is delimited by a support flange  51 . Furthermore, the fixing bushing  18 , the first shell section  49 , the second shell section  50  and the support flange  51  are realized as a high-strength bearing bracket  52  produced in one piece— FIGS. 2 and 3 . Metal, composite material or the like are suitable materials for the bearing bracket. 
     The bearing bracket  52  is suitable for receiving the fuel injection nozzle  3 . It is however also possible for the bearing bracket  52  to be structurally designed such that two fuel injection nozzles, specifically  3  and  3 ′, can be fastened thereto— FIG. 2 . For this purpose, the fastening bolt  15  is suitable as a single holding device, which fastening bolt holds the bearing bracket  52  in position on the housing section  5  of the engine housing  6  of the internal combustion engine  1 . The fastening bolt  15  extends, in a central longitudinal plane E-E between the internal bores  19  and  19 ′ of the fixing bushings  18  and  18 ′ of the bearing bracket  52 , through a bracket bore  53  in a turned-up reinforcement  54  of the bearing bracket  52 . A sealing device Dv is provided between the support flange  51  of the bearing bracket  52  and a contact plane  55  of the housing section  5 . In the exemplary embodiment, the bearing bracket  52 , the fuel injection nozzles  16  and  16 ′, the spring systems  23  and  23 ′ and the insert elements  20  and  20 ′ or the fixing clips  27  and  27 ′ form a prefabricated structural unit  56 — FIG. 2 . 
     Finally, for the installation of the fixing clips  27  and  27 ′ in the form of insert elements  20  and  20 ′ and of the injection nozzles  3 ,  3 ′, it is recommended to use the following method: the spring system  23  and subsequently the fuel injection nozzle  3 , for example, are inserted into the fixing bushing  18 . Then, the spring system  23  is subjected, via the first stop  21 , to load in the axial direction A-A of the fuel injection nozzle  3  such that the fixing clip  27  can be inserted in the radial direction D-D of the fuel injection nozzle, in such a way that the axial securing collar  42  of the fixing bushing  18  engages over the transverse web  30  of the fixing clip  27  such that the fixing clip  27  is radially secured in the axial direction A-A, and the fuel injection nozzle  3  is secured both axially and radially in the bearing bracket  52 , after the spring system is relieved of load. The uninstallation of the fuel injection nozzle  3  is performed in the reverse sequence. 
     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.