Abstract:
A fuel distributor for supplying fuel to injection valves for internal combustion engines includes a hollow manifold having a plurality of branch bores disposed radially therethrough. A plurality of branch lines are operably connected with a manifold at the branch bores by adapters. The adapters have either a one-piece deep-drawn construction or a one-piece extruded construction, and include a mounting flange that conforms to the outer contour of the manifold and joins the adapter to the exterior of the manifold, and a neck portion that closely receives and securely mounts therein the end portions of the branch lines.

Description:
CLAIM OF PRIORITY 
     Applicants hereby claim the priority benefits under the provisions of 35 U.S.C. §119, basing said claim of priority on German Patent Application Serial No. 10 2009 051065.6, filed Oct. 28, 2009. In accordance with the provisions of 35 U.S.C. §119 and Rule 55(b), a certified copy of the above-listed German patent application will be filed before grant of a patent. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a fuel distributor for supplying fuel to injection valves in an internal combustion engine. 
     The generation of pressure and the injection of fuel are not typically integrated or connected to one another in fuel distribution systems. Rather, a fuel pump generates pressure continuously. This pressure, which is built up independent of the injection sequence, is continuously or permanently available in the fuel distributor, which functions as an accumulator unit. In addition, the compressed fuel is accumulated in a manifold, and then distributed to the injectors via branch lines, or is otherwise made available to injection valves in a cylinder bank. 
     Prior art fuel distributors are known from DE 196 07 521 C1, DE 197 53 054 C2, and EP 0 866 221 B1. 
     DE 197 44 762 A1 describes an injection device for a diesel engine in which the fuel distributor comprises a drawn or rolled pipe. Connecting nipples are welded or soldered to this pipe. Insertion bores for receiving the connecting nipples are added to the fuel distributor. The connecting nipples are placed in the insertion bores prior to welding or soldering. 
     Moreover, disclosed in EP 0 122 848 is a method for producing a hydraulic connection for a hollow body. For this arrangement, a neck-shaped adapter branch is provided on the hollow body. A connecting line is placed on the adapter branch, and is then fixed in place by deforming the wall of the branch. 
     Connecting elements embodied as threaded bushings are disclosed in WO 2007/033738 A2 and DE 38 21 827 C2 for connecting branch lines to manifolds of fuel distributors. A sealing seat is produced by mechanical machining of the manifold. These threaded bushings are relatively expensive. In addition, the branch line must be provided with a clinch head or sealing nipple. The end of the branch line and the threaded bushing are generally connected via a union nut, resulting in additional costs. Moreover, assembling the branch line is more complex. In addition, there is also a risk of leaks. 
     Machining the manifold results in high manufacturing costs. In addition, meeting that the requirements for cleanliness in the fuel area has proved problematic, especially the requirement that none of the waste from machining remains in the manifold. 
     The connecting elements, either turned and/or milled parts, are also complex and relatively expensive to produce. Moreover, solid thick-walled connecting components combined with comparatively thin-walled manifolds are not an ideal combination for joining, especially for soldering. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to create a simple and cost-effective solution for connecting branch lines to a manifold of a fuel distributor, wherein requirements regarding tightness against fuel leaks and mechanical stresses are satisfied or fully met. 
     This object is attained in accordance with the present invention in a fuel distributor in accordance with the features of patent claim  1 . 
     Advantageous embodiments and refinements of the present inventive fuel distributor are the subject-matter of dependent claims  2  through  8 . 
     The present fuel distributor has a manifold for receiving pressurized fuel. A plurality of branch bores are added to the manifold. The branch bores extend in the radial direction of the manifold, penetrating the wall of the manifold, and open into the interior pressure chamber of the manifold. One branch line is connected to each branch bore via an adapter. In accordance with the present invention, adapters are embodied as either one-piece deep-drawn parts or one-piece extruded parts. Each adapter partly encloses the manifold radially. To this end, each adapter has a mounting flange that conforms to the outer contour of the manifold, and is used to join the adapter to the manifold. Moreover, the adapter has a neck that is oriented radially with respect to the manifold, and corresponds to an associated branch bore. An end portion segment of each branch line engages in the neck of the adapter, and is joined thereto. The adapter can be produced cost effectively with a minimum amount of material using a deep-drawn or extruded construction, especially a cold extruded construction. 
     The adapter provides a simple, cost-effective solution for connecting branch lines to the manifold of a fuel distributor. The connection is particularly suitable for manifolds that do not have a thick wall. 
     The neck on the adapter is produced using a pre-formed draft disposed radially to the surrounding surface. The end segment of a branch line is received and joined in the neck. A fuel-tight connection that is mechanically very strong is created between the manifold and branch line in this manner. 
     In one advantageous embodiment of the present invention, a stop is formed on the interior circumference of the neck for positioning the end segment of the branch line. The stop is in particular formed by displacing material in the neck, specifically using at least two projections, and preferably three projections, arranged offset to one another on the interior circumference. The projections formed by the displaced material in the neck act as an axial limit for the insertion depth of the branch line. In particular, they also act as a limit for the insertion depth of a soldering ring that is inserted into the neck to form a soldered joint between the neck and the branch line. 
     Another advantage of the neck construction is that an axial tolerance compensation is achieved by the sliding seat of the end segment of the branch line in the neck. This can compensate for fluctuations or variations in the pipe length of the branch lines. 
     For practical applications, it is particularly advantageous that soldering rings be inserted towards the stop in the axial direction of the neck from both sides. The adapter is joined to the manifold, and the branch line is joined in the neck of the adapter at the same time. It is not necessary to use soldering paste on the articles. In addition, this construction ensures that the fuel-tight soldered joint is very reliable. 
     In another embodiment of the present inventive fuel distributor, which is particularly advantageous in practical applications, the end segment of the branch line extends into the branch bore in the manifold and/or penetrates the branch bore. The end segment is then preferably fixed in the branch bore and joined, especially soldered, in the neck. The adapter assumes a supporting function for reducing changes in stiffness, and for improving resistance to vibration in the area in which the branch lines are joined to the manifold. This improves the overall construction of the fuel distributor and lengthens the service life of the same. This embodiment is particularly suitable for high and extremely high fuel pressures. 
     Moreover, at least one aperture may be provided in the adapter. The aperture is used for applying joining material, especially soldering material. In addition, the joint and the joining process may be visually inspected through the aperture. The aperture is preferably provided in the transition area between the mounting flange and the neck of the adapter. 
     Ideally, weld projections are provided on the joining surface of the mounting flange which pre-fix the adapter to the manifold. The welding projections pre-fix the adapter using resistance welding, and then the final fuel-tight seal is attained by soldering or welding, in particular laser welding. 
     A two-step mounting construction is also possible. In this case, the adapter is first joined to the manifold, for instance by soldering. The branch line is welded to the neck of the adapter, especially using inductive soldering or laser welding. This avoids undesired warping and loss of strength due to heat on the branch lines. 
     These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings. 
     The invention shall be explained in greater detail in the following using an exemplary embodiment depicted in the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective elevation of an inventive fuel distributor; 
         FIG. 2  is a vertical section through the depiction in  FIG. 1  along the line A-A; and, 
         FIG. 3  is a vertical section through another embodiment of an inventive fuel distributor. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For purposes of description herein, the terms “upper”, “lower”, “right”, “left”, “rear”, “front”, “vertical”, “horizontal” and derivatives thereof shall relate to the invention as oriented in  FIGS. 1 and 2 . However, it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     An inventive fuel distributor  1  embodying the present invention is explained using  FIGS. 1 through 3 .  FIG. 2  depicts a first embodiment of a fuel distributor  1 , and  FIG. 3  depicts a second embodiment. Equivalent components and parts have the same labels or reference numerals. 
     The illustrated fuel distributor  1  is part of the accumulator injection system for an internal combustion engine, wherein fuel pressure generation and fuel injection are not integrated or connected to one another. Rather, a separate high-pressure pump generates fuel pressure continuously. This fuel pressure, which is independent of the injection sequence, is continuously or permanently available in the fuel distributor  1 . 
     The illustrated fuel distributor  1  includes a hollow manifold  2  having a pump-side fuel inlet  3 . Fuel is conducted through manifold  2  into a compression chamber  5  in the interior of the manifold  2  via a connecting line  4 . The statically compressed fuel is accumulated in the manifold  2 , and made available for distribution to the injectors in a cylinder bank (not shown) via a plurality of branch lines  6 ,  6 ′. To this end, radially oriented branch bores  7 ,  7 ′ are provided in the manifold  2 . The compression chamber  5  communicates with the branch lines  6 ,  6 ′ via these radial branch bores  7 ,  7 ′ to conduct fluid fuel. 
     Each of the branch lines  6 ,  6 ′ is connected to the manifold  2  via an adapter  8 ,  8 ′. The illustrated adapter  8 ,  8 ′ has either a one-piece deep-drawn construction or a one-piece extruded construction. Adapter  8 ,  8 ′ has a mounting flange  9 ,  9 ′ shaped to conform with the outer contour of the manifold  2 . The adapter  8 ,  8 ′ is joined to the manifold  2  via this mounting flange  9 ,  9 ′. A neck  10 ,  10 ′ that is oriented radially to the manifold  2  is constructed as a deep-drawn or extruded draft on the adapter  8 ,  8 ′. A final end segment  11 ,  11 ′ of the branch line  6 ,  6 ′ engages and is joined to the neck  10 ,  10 ′. 
     The mounting flange  9 ,  9 ′ is configured in a crown-like manner about the neck  10 ,  10 ′ and covers a portion of the outer circumference  12  of the manifold  2 . 
     In the embodiment of the fuel distributor  1  shown in  FIG. 2 , a stop  14  is provided on the inner circumference  13  of the neck  10 . The stop  14  ensures the proper axial positioning of the end segment  11  in the neck  10 . The stop  14  is produced by an inelastic displacement of material on the inner circumference  13  of the neck  10 , specifically in the form of three inward projections  15  arranged offset to one another on the inner circumference  13 . Stops  14  constitute the axial limit for the insertion depth of the branch line  6 , and they are also a positioning aide for solder rings inserted into the neck  10 . The neck  10  and branch line  6  can be joined by soldering these soldering rings. The soldering rings may be inserted from both sides of the neck  10  and positioned at the stop  14 . The solder that melts when heated then fixes the end segment  11  of the branch line  6  in the neck  10 , and it also simultaneously fixes the mounting flange  9  on the outer circumference  12  of the manifold  2 . 
     In the illustrated example, weld projections  17  are provided on the joining surface  16  of the mounting flange  9 . These projections  17  are used for pre-fixing or for joining the adapter  8  to the manifold  2  using resistance welding. Then, the mounting flange  9  and manifold  2  are joined by soldering or welding to create a fuel-tight material bond or seal. 
     A two-step mounting process is also possible. First, the adapter  8  is joined to the manifold  2 , for instance using soldering. Then, the branch line  6  and adapter  8  are joined, preferably using inductive soldering or laser welding. 
     As  FIG. 3  depicts, in an alternate embodiment of the fuel distributor  1 , the end segment  11 ′ of the branch line  6 ′ is inserted into the branch bore  7 ′, and projects into compression chamber  5 . The end segment  11 ′ is joined, preferably soldered, to the manifold  2  in the branch bore  7 ′, and to the neck  10 ′ of the adapter  8 ′. It can be seen that the end segment  11 ′ terminates generally flush with the wall of the manifold  2  inside the manifold  2 . 
     The adapter  8 ′ provides an additional supporting function for reducing changes in stiffness, and for improving resistance to vibration at join locations, and thus the strength of fuel distributor  1 . 
     Moreover, it can be seen that apertures  19  are provided in the transition area  18  between the mounting flange  9 ′ portion of adapter  8 ′ and the neck portion  10 ′ of adapter  8 ′. Joining material, such as a solder material, may be applied through the apertures  19 . In addition, the apertures  19  may be used to control and inspect the joining process, and the joint that is produced. 
     Otherwise, the process for joining adapter  8 ′ and manifold  2  is similar to that described in the foregoing, so that the explanation will not be repeated. 
     The adapters  8 ,  8 ′ that have been produced by deep-drawing or extrusion are cost-effective, both in terms of production and material usage. In addition, they are better than known proposals in terms of weight. The adapter  8 ,  8 ′ can be produced either as a one-piece deep-drawn part, or as a one-piece extruded part, using a small amount of material and without mechanical machining. A simple and cost-effective solution for connecting branch lines  6  to the manifold  2  is thereby created. In particular, even those manifolds  2  that have a thinner wall than those of a conventional construction may be used in a fuel distributor  1 . 
     In the foregoing description, it will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed herein. Such modifications are to be considered as included in the following claims, unless these claims by their language expressly state otherwise. 
     LEGEND 
     
         
         
           
               1 —Fuel distributor 
               2 —Manifold 
               3 —Fuel inlet 
               4 —Connecting line 
               5 —Pressure chamber 
               6 —Branch line 
               6 ′—Branch line 
               7 —Branch bore 
               7 ′—Branch bore 
               8 —Adapter 
               8 ′—Adapter 
               9 —Mounting flange 
               9 ′—Mounting flange 
               10 —Neck 
               10 ′—Neck 
               11 —End segment of  6   
               11 ′—End segment of  6 ′ 
               12 —Outer circumference of  2   
               13 —Outer circumference of  10   
               14 —Stop 
               15 —Projection 
               16 —Join surface 
               17 —Weld projection 
               18 —Transition area 
               19 —Aperture