FIELD OF THE INVENTION 0001 The present invention relates to a fuel injection system for injecting fuel into an internal combustion engine, especially for the direct injection of fuel into the combustion chamber, or the combustion chambers, of the internal combustion engine.

BACKGROUND INFORMATION 0002 A fuel injection system is known from German Published Patent Application No. 197 25 076. To provide a sealing connection, the fuel injection system includes an annular sealing support between a fuel injector and an associated connecting piece of a fuel-distributor line, the sealing support cooperating with a first sealing element to seal the sealing support from an end face of an intake section of the fuel injector, and cooperating with a second sealing element to seal the sealing support from the connecting piece of the fuel-distributor line. A bushing, which can be inserted into a fuel-intake orifice of the intake section, penetrates the annular sealing support, thereby retaining the sealing support between an upstream collar of the bushing and the intake section of the fuel injector in a manner allowing movement in the radial direction. 0003 A particular disadvantage of the system described in the aforementioned printed publication is that, because of the manufacturing tolerances of both the receiving bore for the fuel injector and also the connecting piece at the fuel-distributor line, positional deviations and angular deviations can occur between the intake section of the fuel injector, on the one hand, and the connecting piece of the fuel-distributor line, on the other hand. The seal positioned between the intake section of the fuel injector and the connecting piece of the fuel-distributor line compensates for the positional and angular deviations only to a limited, insufficient extent. In the positional and angular deviations that occur in practice, there is the danger in known fuel injection systems that fuel escapes at the seal where insufficient compensation for positional and angular deviations is provided.

SUMMARY OF THE INVENTION 0004 In contrast, the fuel injection system according to the present invention has the advantage over the related art that, by inserting the connecting piece into a recess of the fuel injector, a substantially space-saving connection is produced. A spring element disposed between the connecting piece of the fuel-distributor line and an intake connection piece of the fuel injector, is able to compensate for manufacturing tolerances, for tilting during installation of the fuel injector in the cylinder head, as well as for uneven warming during operation of the internal combustion engine, in an effective and space-saving manner. 0005 It is advantageous that, depending on the prevailing holding-down forces, the spring element may be designed in different variants as a conical spring washer or helical spring. 0006 Furthermore, it is advantageous that the fuel injectors are able to be preassembled at the fuel-distributor line with the aid of a holding clamp, thereby saving considerable time during the final assembly of the fuel injectors in the cylinder head. 0007 The fuel-distributor line is advantageously screwed to the cylinder head, or connected to the cylinder head using hold-down devices or similar devices.

BRIEF DESCRIPTION OF THE DRAWINGS 0008 FIG. 1 shows a section through a first exemplary embodiment of a fuel injection system according to the present invention, in an overall view. 0009 FIG. 2A shows a section through an individual fuel injector of the fuel injection system shown in FIG. 1. 0010 FIG. 2B shows a second exemplary embodiment of a fuel injector designed according to the present invention, suited for installation in the fuel injection system.

DETAILED DESCRIPTION 0011 FIG. 1, in a schematic section, shows an overall view of a first exemplary embodiment of a fuel injection system designed according to the present invention, which, in the current exemplary embodiment, includes four fuel injectors 1. Fuel injectors 1, preferably in the form of high-pressure fuel injectors 1, are suited for the direct injection of fuel into the combustion chambers of a mixture-compressing internal combustion engine having external ignition. In the following, only those components are discussed that have a direct connection to the measures according to the present invention. 0012 Fuel injectors 1 are installed in a series configuration in a cylinder head 2 of the internal combustion engine and are interconnected by a fuel-distributor line 3. The measures according to the present invention relate to the connection of fuel injectors 1 to fuel-distributor line 3. 0013 Fuel injectors 1 are joined to fuel-distributor line 3 by seals 4, which are inserted into groove-type depressions at the outer circumference of connecting pieces 5 of fuel-distributor line 3. Connecting pieces 5 are designed to each be insertable into a recess 6 in inflow-side ends 7 of fuel injectors 1. A reliable sealing effect may be achieved between fuel-distributor line 3 and fuel injectors 1 by pinching seals 4. 0014 In addition, a spring element 8 is provided in each case to transmit to fuel injectors 1 the pressure force of fuel-distributor line 3, which may be connected to cylinder head 2, for instance, by holding devices or clamps (not shown). In the present first exemplary embodiment, this spring element is designed as a conical spring washer 8a. Conical spring washers 8a are inserted between connecting pieces 5 of fuel-distributor line 3 and inner support surfaces 9 in recesses 6 of fuel injectors 1 and, by their initial stress, transmit the holding-down forces of fuel-distributor line 3, which is pulled to cylinder head 2 by holding devices, to fuel injectors 1, thereby pressing them into cylinder head 2. Sealing rings 10, which are pressed between fuel injectors 1 and cylinder head 2, may be provided to seal cylinder head 2 from the combustion chambers. Support surfaces 9 in recesses 6 are formed at supporting disks 14, for instance, which are disposed, for example, on the inner poles 15 of fuel injectors 1. 0015 Holding clamps 11 are provided to attach connecting pieces 5 to fuel injectors 1; they are suited, in particular, for premounting fuel injectors 1 at fuel-distributor line 3, since the entire fuel injection system may then be installed as a whole in or at cylinder head 2. Holding clamps 11 reach around connecting pieces 5 of fuel-distributor line 3 and extend up to end 7 on the intake side of fuel injectors 1. There, they are preferably anchored by screws 12 in a plastic extrusion coating 13 of fuel injectors 1. Alternatively, projecting lips, which engage with openings of holding clamp 11, may be provided at plastic extrusion coating 13. 0016 To illustrate the measures according to the present invention, FIG. 2A shows an individual fuel injector 1 into which connecting piece 5 of fuel-distributor line 3 has been inserted, and which includes holding clamp 11. Corresponding components are denoted by corresponding reference numerals. 0017 As already explained in connection with FIG. 1, fuel injector 1 includes a spring element 8 between connecting piece 5 of fuel-distributor line 3 and supporting disk 14, which is designed as a conical spring washer 8a in the present exemplary embodiment. On the one hand, conical spring washer 8a transmits the holding-down forces of fuel-distributor line 3, and, on the other hand, makes it possible to compensate for misaligments and tilting of fuel injector 1, which may occur, for instance, as a result of manufacturing tolerances of the individual components, by a skewed installation of fuel injector 1 in cylinder head 2, or of warming of cylinder head 2 and fuel injector 1 during operation of the internal combustion engine. In this way, reliable sealing is achieved, on the one hand, of cylinder head 2 from the combustion chamber of the internal combustion engine and, on the other hand, of fuel injector 1 from fuel-distributor line 3. 0018 FIG. 2B, in the same view as FIG. 2A, shows a second exemplary embodiment of a fuel injector 1 to be installed in the fuel injection system designed according to the present invention. 0019 In the present second exemplary embodiment, spring element 8 is designed in the form of a helical spring 8b. It has the particular advantage of being easy to produce and of having greater flexibility compared to conical spring washer 8a, since conical spring washers 8a, in most cases, have a higher spring constant, especially when having small radii. Helical spring 8b allows for a more even compensation for misalignments and tilting. Helical spring 8b, for instance, is braced directly against inner pole 15 of fuel injector 1. 0020 The present invention is not restricted to the exemplary embodiments shown and is also suited, for instance, for fuel injection systems of mixture-compressing internal combustion engines having self-ignition.