Fuel injector

Abstract

Fuel injection valve (1) with a nozzle body (9) that can be inserted into a recess (14) of a cylinder head (12) and a valve housing with an inlet-side end (2) which can be connected to a connecting nozzle (27) of a fuel distribution line (24), wherein the inlet-side end (2) is designed as an elongated connecting sleeve (7), characterized in that the connecting sleeve (7) has at least one constriction (10) to reduce its section modulus, so that it is deformable under the influence of radial forces, wherein the constriction (10) extends in an off-center section of the connecting sleeve (7) away from the inlet-side end (2) over 1 / 5 of the total length of the connecting sleeve (7) or extends in a central section of the connecting sleeve (7) over 1 / 4 of the total length of the connecting sleeve (7).

Description

State of the art

[0001] The invention relates to a fuel injection valve according to the preamble of the main claim.

[0002] Various installation types are known in the prior art to compensate for manufacturing tolerances of a fuel injection valve.

[0003] From DE 197 35 665 A1, for example, a fuel injection valve is known in which a compensating element, consisting of a support body with a spherical bearing surface, is used to compensate for tolerances in the manufacturing and assembly of the fuel injection valves. The fuel injection valve rests on this compensating element in a receiving bore of a cylinder head. Since the fuel injection valve rests on the spherically shaped spherical bearing surface, it can be mounted with up to a certain angular deviation from the axis of the receiving bore and pressed firmly into the receiving bore by suitable means, such as a clamping jaw. This arrangement allows for adjustment of the fuel supply lines; however, the support body requires complex manufacturing and a precisely manufactured spherical surface.The rigid support body cannot be compressed, and therefore no compensation can be made in the axial direction of the cylinder head's receiving bore. Compensation for tolerances can only be achieved on the predefined geometry of the spherical surface.

[0004] Another solution for compensating for tolerances, as proposed in DE 101 40 797 A1, involves providing a compensating element in the form of an intermediate ring, which is positioned between the valve housing of the fuel injector and a wall of a receiving bore in the cylinder head. The intermediate ring further comprises webs extending along the valve housing, to which support segments are attached that encompass the valve housing, thus spacing the valve housing from the wall of the receiving bore. However, with this arrangement, even slight inclinations result in significant lateral forces acting on the fuel injector and the seals during installation.

[0005] Furthermore, DE 197 35 665 A1 describes a fuel injection valve which uses a tubular intermediate piece to compensate for positional and angular deviations resulting from manufacturing tolerances and assembly-related tolerances. This intermediate piece is arranged between the fuel inlet opening of each fuel injection valve and the associated fuel outlet opening and can be connected to the fuel inlet opening of the associated fuel injection valve and the fuel outlet opening of the fuel distribution line in a sealing manner and movably within specified limits, so that the inlet section of the fuel injection valve can be flexibly mounted on the fuel distribution line via the intermediate piece.However, a disadvantage here is that two sealing points, each requiring its own O-ring, are created, resulting in drawbacks such as increased costs and the additional risk of leakage. Furthermore, the intermediate piece represents an additional component that requires installation space, which is particularly disadvantageous in centrally located installations where space is very limited.

[0006] German patent DE 103 38 715 A1 proposes a fuel injection valve with a compensating element for mounting the valve in the cylinder head of an internal combustion engine. The compensating element is annular and is arranged between the valve housing of the fuel injection valve and a wall of a receiving bore in the cylinder head. The compensating element has at least two legs that bear against the fuel injection valve and the cylinder head. However, a disadvantage of this design is that it also requires an additional element, namely the support element, and the corresponding installation space for it.

[0007] A disadvantage of all the fuel injection valves mentioned above is that they require a complex design or additional components to compensate for tolerances, which increases the costs accordingly.

[0008] Furthermore, a fuel injection valve is already known from EP 1 445 474 A1, which is particularly suitable for the direct injection of fuel into a combustion chamber of an internal combustion engine. The fuel injection valve has a nozzle body that can be inserted into a recess in a cylinder head. The valve housing also has an inlet end that can be connected to a connecting piece of a fuel distribution line, the inlet end being designed as an elongated connecting sleeve. The connecting sleeve is designed as a flexible bellows or corrugated bellows with a plurality of axially successive folds or corrugations.

[0009] From DE 197 05 990 A1, a mounting device for installing a fuel injection valve in a receiving bore of a cylinder head of an internal combustion engine is already known. The mounting device has a housing body that at least partially encompasses the fuel injection valve. The mounting device, together with the fuel injection valve, can be inserted into the receiving bore. The fuel injection valve has an elongated connecting nozzle, which can be partially gripped by the mounting device. The connecting nozzle does not have a constant outer diameter along its axial length, but rather has at least one radial flange, which ensures that smaller diameter longitudinal sections of the connecting nozzle follow before and after it. The mounting device can engage under the radial flange with an inwardly angled collar section. Advantages of the invention

[0010] In contrast, the fuel injection valve according to the invention, with the characterizing feature of the main claim, has the advantage that, due to the elongated design of the connecting sleeve for the purpose of tolerance compensation, it possesses a low moment of resistance and deforms accordingly even under small transverse forces. Thus, tolerance compensation is achieved in a simple manner and without complex additional parts.

[0011] To further reduce the resistance moment, the connecting sleeve has, according to the invention, a constriction which can be arranged at different positions and with different lengths on the connecting sleeve.

[0012] A further advantage is the support of the fuel injector in the cylinder head. If the fuel injector is supported on an incline of, for example, 45° in a correspondingly shaped recess in the cylinder head, this has the benefit of simultaneously centering the fuel injector during installation. The deformation of the connecting sleeve for tolerance compensation only occurs under the influence of the holding force and the pressure in the so-called rail, which acts on the cross-section of the rail cup.

[0013] The fuel injection valve only has to absorb minor lateral forces that do not lead to a change in its function or strength.

[0014] The fuel injection valve according to the invention therefore offers particular advantages in terms of installation, which is especially true for central installation, and reduces the number of parts to be assembled in manufacturing. drawing

[0015] Exemplary embodiments of a fuel injection valve according to the invention, as well as of a fuel injection valve according to the prior art, are shown in simplified form in the drawing and are explained in more detail in the following description. The drawing shows: Fig. 1A a schematic cross-section through a fuel injection valve according to the state of the art; Fig. 1B a schematic cross-section through another fuel injection valve according to the prior art; Fig. 2 an embodiment of the fuel injection valve according to the invention; Fig. 3A - 3F various examples of terminal sleeves, whereby Fig. 3A and Fig. 3F Exemplary embodiments of connecting sleeves of the fuel injection valve according to the invention are shown; Fig. 4A - 4E Schematic cross-sections through further embodiments of connecting sleeves of the fuel injection valve according to the invention; and Fig. 5A, Fig. 5B Sections of a spray-side end of the fuel injection valve according to the invention. Description of the exemplary implementations

[0016] Fig. Figure 1A shows a schematic cross-section through a prior art fuel injection valve 1, which uses an intermediate piece 17 to compensate for manufacturing tolerances and assembly-related tolerances. A combustion chamber 18 of the internal combustion engine is closed off by means of a cylinder head 12. The cylinder head 12 has a receiving bore or recess 14 into which a spray-side end 8 of a fuel injection valve 1 can be inserted. The recess 14 is sealed against the combustion gases of the combustion chamber 18 by a ring seal 19.

[0017] On the side furthest from the combustion chamber 18, a recess 20 formed in the cylinder head 12 adjoins the recess 14. This recess receives a flange 21 of the fuel injection valve 1 inserted into the recess 14. The flange 21 rests on a flat support surface 22 of the cylinder head 12 and is pressed against this support surface by means of a clamping device 23. The clamping force exerted by the clamping device 23 is greater than the counterforce exerted by the combustion pressure of the combustion gases in the combustion chamber 18, so that the spray-side end 8 of the fuel injection valve 1 is securely fixed to the cylinder head 12 even at high combustion pressure.

[0018] A fuel distribution line 24 is provided to supply the fuel injection valve 1. The fuel distribution line 24 is tubular and extends along an axis 26 oriented perpendicular to the longitudinal axis 25 of the fuel injection valve 1 and the recess 14 of the cylinder head 12. At the position of each fuel injection valve 1, the fuel distribution line 24 has a connecting piece 27, which is designed in the form of a stepped hollow cylinder and has a guide section 28 that is connected to the main channel 30 of the fuel distribution line 24 via a connecting channel 29.

[0019] In the area of ​​the connecting piece 27, the fuel distribution line 24 has a fuel outlet opening 31 for each fuel injection valve 1. Downstream of the fuel outlet opening 31 of the fuel distribution line 24 is the intermediate piece 17, which supplies the fuel to a fuel inlet opening 32 at an inlet section 33 of the fuel injection valve 1. The intermediate piece 17 has an upstream, tapered section 34, which can be inserted into the guide section 28 of the connecting piece 27 and is sealed against the connecting piece 27 of the fuel distribution line 24 by means of a first sealing element 35 designed as an O-ring.

[0020] The upstream tapered section 34 of the intermediate piece 17 is slidably displaceable within the guide section 28 of the connecting piece 27 by the first sealing element 35 sliding along the inner wall of the guide section 28. Furthermore, the intermediate piece 17 is pivotable relative to the connecting piece 27 within predetermined limits, with the first sealing element 35 compensating for the changing gap between the upstream tapered section 34 of the intermediate piece 17 and the guide section 28 of the connecting piece 27 during pivoting. The intermediate piece 17 also has a downstream section 36, on the inner diameter of which a guide section 37 for the inlet section 33 of the fuel injection valve 1 is formed.

[0021] The inlet section 33 has a second sealing element 38 designed as an O-ring, which seals the gap between the downstream section 36 and the inlet section 33 of the fuel injection valve 1. The inlet section 33 is also slidably displaceable in the guide section 37 by means of the second sealing element 38 sliding along the inner wall of the downstream section 36 of the intermediate piece 17. Furthermore, the inlet section 33 is pivotable relative to the intermediate piece 17 within predetermined limits, whereby the sealing element 38 is slightly deformed during pivoting and compensates accordingly for the change in the gap between the downstream section 36 of the intermediate piece 17 and the inlet section 33 of the fuel injection valve 1.

[0022] The sliding and pivoting arrangement of the intermediate piece 17 on the connecting piece 27, on the one hand, and the sliding and pivoting arrangement of the inlet section 33 of the fuel injection valve 1 on the intermediate piece 17, on the other hand, creates a hinged, adjustable, and shortenable / extendable telescopic connection between the fuel distribution line 24 and the fuel injection valve 1, enabling flexible installation of the fuel distribution line 24. Any angular or positional misalignment of the inlet section 33 due to installation can be compensated for by means of the intermediate piece 17. However, as already mentioned, the provision of the intermediate piece is structurally complex, and the use of two sealing elements leads to the previously mentioned problems of potential leakage.

[0023] Fig. Figure 1B shows a schematic partial cross-section through another fuel injection valve 1 according to the prior art, which has a standard length. The in Fig. The fuel injection valve 1 shown in Figure 1B is designed as a direct-injection fuel injection valve, which can be used to directly inject fuel into a combustion chamber of a combustion engine (not shown), in particular a mixture-compressing, spark-ignition internal combustion engine, into a valve receptacle of a cylinder head. The fuel injection valve 1 has a plug connection at an inlet end 2 to a receiving port of a fuel distribution line 3, which is sealed by a seal 4 between the fuel distribution line 3 and a supply port 5 of the fuel injection valve 1. The fuel injection valve 1 has an electrical connection 6 for electrical contact to actuate the fuel injection valve 1.

[0024] Compared to the standard length fuel injector 1, in Fig. Figure 2 shows the fuel injection valve 1 according to the invention, which also has a plug connection at an inlet-side end 2 to a receiving nozzle of a fuel distribution line 3, which is not shown here. A seal 4 is provided at an inlet nozzle 5 to seal the fuel injection valve 1. Furthermore, the fuel injection valve 1 according to the invention also has an electrical connection 6. The inlet-side end 2 of the fuel injection valve 1 is designed as an elongated tube to provide a low resistance torque and to be deformable under the influence of radial forces, thereby compensating for manufacturing tolerances. A nozzle body 9, which can be inserted into a recess of a cylinder head, is formed at an outlet-side end 8 of the fuel injection valve.A connecting sleeve 7, forming the inlet end of the fuel injection valve 1 and designed as part of the valve housing, is, for example, formed by deep drawing. The connecting sleeve 7 and the electrical connection 6 can also be encased in a plastic overmolding.

[0025] Fig. 3A and Fig. Figure 3F shows various embodiments for connecting sleeves 7 of the fuel injection valve 1 according to the invention, while the Fig. Figures 3B to 3E show further examples of connection sleeves 7. The connection sleeve 7 can be provided in various shapes. Fig. Figure 3A shows a connecting sleeve 7 which has a constriction 10 in a section remote from the supply line nozzle 5, extending over approximately 1 / 5 of the total length of the connecting sleeve 7. In contrast, Figure 3 shows Fig. 3B a connecting sleeve 7 with constant diameter and constant wall thickness, wherein the diameter, wall thickness and length of the connecting sleeve 7 are decisive for the section modulus. In Fig. Figure 3C shows a connecting sleeve 7 in which the constriction extends over almost the entire length of the pipe.

[0026] Fig. 3D shows a connecting sleeve 7, which is designed, for example, in sections in the form of a bellows or corrugated tube. Fig. 3E represents a connecting sleeve 7 in which the inner pipe diameter is constant, but the wall thickness of the connecting sleeve 7 varies over its length. Fig. 3F shows a connecting sleeve 7, which is similar to the one in Fig. The connecting sleeve 7 shown in 3A is, however, with the difference that the constriction 10 is provided in a central section and extends over about 1 / 4 of the total length of the connecting sleeve 7.

[0027] Fig. Figures 4A to 4E are schematic cross-sections or partial sections through further embodiments of connecting sleeves 7 of the fuel injection valve 1 according to the invention, wherein Fig. 4A and Fig. Figure 4B shows connecting sleeves 7, which are designed with different diameter steps, i.e., the connecting sleeve 7 has various constrictions 10, 11 of different diameters. In contrast, Figure 4B shows... Fig. 4C a connecting sleeve 7, the shape of which is characterized by a conical profile. In Fig. Figure 4D further shows a connecting sleeve 7, which has two oppositely tapered sections 40 separated by a constriction 10 between them. Finally, in Fig. 4E shows a connecting sleeve 7 which has a convex section 41.

[0028] Another alternative embodiment of the connecting sleeve 7 has a concave shape, which is shown by the dashed line 42 in Fig. 4E is indicated. The exemplary embodiments illustrate that, in order to reduce the section modulus of the connecting sleeve 7, many possibilities are provided by appropriate design of the sleeve; the constriction 10 can be arranged at different positions and with different lengths on the connecting sleeve 7; the connecting sleeve 7 can be designed with a constant diameter and constant wall thickness, in which case the diameter, wall thickness, and length of the connecting sleeve 7 are decisive for the section modulus; or the connecting sleeve 7 can be designed with a constant inner or outer diameter, and the wall thickness can vary. In each case, the design according to the invention allows for deformation to compensate for tolerances. The connecting sleeve 7 can be manufactured by deep drawing or rotary swaging.

[0029] Fig. 5A and Fig. Figure 5B shows sections of an injection-side end 8 of the fuel injection valve 1 according to the invention, which illustrate various mounting options for the fuel injection valve 1 in a cylinder head 12. According to the Fig. In the embodiment shown in Figure 5A, a recess 14, which is provided in the cylinder head 12 for receiving the nozzle body 9 of the fuel injection valve 1, has a surface 15 chamfered, for example, at an angle of 45°. The nozzle body 9 of the fuel injection valve 1 also has a surface 16 chamfered at an angle of 45°. The two surfaces 15, 16 are congruent in shape and abut each other. In contrast, according to the [reference to Figure 5A] Fig.In the embodiment shown in Figure 5B, the fuel injection valve 1 can also rest directly on or be supported by a flat surface 13 formed in the recess 14 of the cylinder head 12. The provision of the chamfered surfaces 15, 16, particularly at an angle of 45°, has the advantage of centering the fuel injection valve 1.

Claims

[1] Fuel injection valve (1) with a nozzle body (9) which can be inserted into a recess (14) of a cylinder head (12) and a valve housing with an inlet-side end (2) which can be connected to a connecting piece (27) of a fuel distribution line (24), wherein the inlet-side end (2) is designed as an elongated connecting sleeve (7), characterized by that the connecting sleeve (7) has at least one constriction (10) for reducing its section modulus, so that it is deformable under the action of radial forces, wherein the constriction (10) extends in an off-center section of the connecting sleeve (7) remote from the inlet-side end (2) over 1 / 5 of the total length of the connecting sleeve (7) or in a central section of the connecting sleeve (7) over 1 / 4 of the total length of the connecting sleeve (7). [2] Fuel injection valve (1) according to claim 1, characterized bythat the connecting sleeve (7) has a constant inner diameter, wherein the wall thickness of the connecting sleeve (7) varies over its length. [3] Fuel injection valve (1) according to one of claims 1 to 2, characterized by that the nozzle body (9) has, on its section which can be received in the cylinder head (12), a bevelled outer surface (16) which is designed to bear against a shape-congruent surface (15) of the cylinder head (12). [4] Fuel injection valve (1) according to claim 3, characterized by , the slope of the bevelled outer surface (16) is 45°. [5] Fuel injection valve (1) according to one of claims 1 to 4, characterized by that the connecting sleeve (7) is thin-walled. [6] Fuel injection valve (1) according to one of claims 1 to 5, characterized by that the connecting sleeve (7) is manufactured by deep drawing or rotary swaging. [7] Fuel injection valve (1) according to one of claims 1 to 6, characterized by that the fuel injection valve (1) is surrounded by a plastic overmold. [8] Fuel injection valve (1) according to one of claims 1 to 7, characterized by that the fuel injection valve (1) serves for the direct injection of fuel into a combustion chamber (18) of an internal combustion engine.

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