Fuel injector arrangement for installing a fuel injector in an internal combustion engine

Abstract

The invention relates to a fuel injector arrangement for installing a fuel injector (1) in an internal combustion engine, the fuel injector (1) being designed for the metered dispensing of liquid or gaseous fuel, and having a housing (5) which comprises an injector body (6) and a jacket tube (10) surrounding the injector body (6), the injector body (6) having a fuel inflow (8) and an injection opening (9) for dispensing the fuel. An annular gap (13) is formed between the jacket tube (10) and the injector body (6) and forms a fuel flow path. A clamping device (30), by which a clamping force (F) is exerted on the fuel injector (1), pushes the fuel injector (1) against a contact face (4) in the internal combustion engine, the clamping device (30) exerting the clamping force at least indirectly onto the jacket tube (10). The end face (14) of the jacket tube (10) facing the injection opening (9) is supported on a pressure face (16) on the injector body (6).

Description

[0001] Description in one

[0002] internal combustion engine

[0003] The invention relates to a fuel injector arrangement for mounting a fuel injector in an internal combustion engine, wherein the fuel injector is preferably used to meter liquid or gaseous fuel into a combustion chamber of an internal combustion engine.

[0004] State of the art

[0005] In direct-injection internal combustion engines, the fuel, which can be gaseous or liquid, is injected directly into the combustion chamber. The fuel is injected into the combustion chamber at high pressure at the right time by a fuel injector, which is usually located in the cylinder head of the internal combustion engine. The fuel-air mixture is then either externally ignited, usually with the help of a spark plug, or ignited solely by the compression of the combustion chamber air, similar to the principle of a diesel engine (compression ignition). Because the fuel injector protrudes into the combustion chamber, it is exposed to the pressure in the combustion chamber. Its installation in the cylinder head must therefore meet the following requirements: Firstly, the fuel injector must withstand the pressure generated by combustion and the corresponding temperatures in the combustion chamber.Secondly, the combustion chamber gases must be sealed off so that they do not escape between the fuel injector and the wall of the bore. For this purpose, a fuel injector is fixed in a bore in the cylinder head with the help of a clamping device, usually a clamping claw or a fixing screw. One such arrangement is known, for example, from DE 101 55 678 A1. The clamping claw is fork-shaped and grips the injector. By tightening a clamping screw, the clamping claw is pressed against the injector, pressing it into the mounting bore of the cylinder head against a corresponding sealing surface. Since the force required for sealing is relatively high, the clamping force causes elastic deformation of the force-transmitting parts of the injector and influences previously adjusted component pairings.For injectors used to inject liquid fuel into the combustion chamber of an internal combustion engine, this deformation is generally not significant. The flow cross-sections within the injector body are relatively small, and the injectors are therefore quite solidly constructed, so the impact force does not cause any significant deformation.

[0006] Injectors for the injection or injection of alternative fuels, particularly gaseous fuels, require significantly larger flow cross-sections in the injector because the energy density of these fuels is significantly lower. In addition, the fuel pressure is much lower than that of liquid fuel, and a correspondingly high fuel flow can only be achieved with a large flow cross-section. Since the installation space in the cylinder head is limited, the injector housing of these fuel injectors has a comparatively thin-walled design. However, the required impact force remains the same, so that the impact force leads to a much greater deformation of the fuel injector and thus to a change in the set functional dimensions in the injector, for example the valve lift or the residual air gap. In addition, the variation in the impact force from one injector to another must also be taken into account.

[0007] Advantages of the invention

[0008] The fuel injector arrangement according to the invention for mounting a fuel injector in an internal combustion engine has the advantage that the fuel injector can be securely mounted in the internal combustion engine with a high impact force, despite relatively large flow cross-sections for the fuel, without the functionality of the fuel injector being impaired due to the impact. For this purpose, the fuel injector arrangement has a fuel injector for the metered delivery of liquid or gaseous fuel, wherein the fuel injector has a housing which comprises an injector body and a jacket tube surrounding the injector body. The injector body has a fuel inlet and an injection opening for delivering the fuel, wherein an annular gap is formed between the jacket tube and the injector body, which forms a fuel flow path.Furthermore, a clamping device is provided that exerts a clamping force on the fuel injector and presses it against a support surface in the internal combustion engine. The clamping device exerts the clamping force at least indirectly on the jacket tube, with the jacket tube resting against a pressure surface on the injector body with an end surface facing the injection opening.

[0009] The pressure surface can be formed at any height of the injector body, so that the impact force can be exerted via the jacket tube surrounding the injector body relatively close to the combustion chamber, i.e., close to the end region of the injector facing the combustion chamber. Thus, the section of the fuel injector surrounded by the jacket tube is not affected by the clamping device, so that the technical problems caused by deformation do not occur in this area of ​​the fuel injector. The fuel injector can thus be reliably and securely mounted in the cylinder head bore of the internal combustion engine despite relatively large flow cross-sections, such as those required particularly for gaseous fuel.

[0010] In a first advantageous embodiment, the clamping force is exerted by the clamping device on the end of the casing pipe facing away from the pressure surface. This end is easily accessible, so that the already known clamping devices or clamping devices can be used.

[0011] In a further advantageous embodiment, the injector body comprises a nozzle body in which the injection opening is formed and which forms the combustion chamber-side end section of the body, with the pressure surface being formed on the nozzle body. This shifts the clamping force introduction to the fuel injector far toward the combustion chamber, which minimizes deformation of the injector body. In particular, the nozzle body, which forms the combustion chamber-side end of the injector body, offers an advantageous location for the pressure surface.

[0012] In a further advantageous embodiment, the pressure surface is formed on the injector body. This can be easily manufactured, for example, using a turning process. Another advantageous embodiment is the pressure surface formed on a snap ring that engages an annular groove on the injector body. Such snap rings are proven and can be easily implemented on various injector bodies.

[0013] In a further advantageous embodiment, the pressure surface is formed on a union nut that is screwed into an external thread formed on the injector body. This creates a pressure surface on the injector body in a simple manner. The union nut can be positioned at any location on the injector body by providing an external thread.

[0014] In a further advantageous embodiment, the jacket tube is formed from two partial jacket tubes that adjoin one another longitudinally, with an intermediate seal arranged between the two partial jacket tubes. This arrangement has the advantage that one partial jacket tube, facing the combustion chamber, can be firmly connected to the injector body, for example, by a screw thread. The second partial jacket tube can be attached from above, i.e., from the side of the injector facing away from the injection opening. This facilitates assembly and thus the installation of the fuel injector assembly in an internal combustion engine.

[0015] In a further advantageous embodiment, a seal is arranged between the end region of the jacket tube facing away from the pressure surface and the injector body. This allows the annular space formed between the jacket tube and the injector body to be reliably sealed, even when the clamping force is applied to the jacket tube. In a further advantageous embodiment, the end surface of the jacket tube facing away from the pressure surface is spherical or conical. In an advantageous embodiment, this can be combined with an additional sleeve arranged between the clamping device and the jacket tube. Since the clamping device presses on the sleeve and this presses on the jacket tube, the sleeve exerts an inward force on the end surface of the jacket tube and thereby prevents - or at least reduces - any relative movement of the injector in the jacket tube.Advantageously, the end face of the sleeve, which interacts with the end face of the jacket pipe, is spherical or conical, so that the inwardly directed force on the end face of the jacket pipe is increased.

[0016] In a further advantageous embodiment, the clamping device is designed as a clamping claw. The clamping claw has the advantage that it can be pushed laterally over the injector, for which purpose it is preferably fork-shaped. This allows high clamping forces to be applied without having to redesign the end area of ​​the fuel injector facing away from the combustion chamber, and it remains freely accessible for additional connections. An inwardly directed clamping surface is advantageously formed on the clamping claw, which exerts an inward force on the jacket tube to bring the jacket tube into contact with the injector body.

[0017] In a further advantageous embodiment, the fuel injector is arranged in a receiving bore of the internal combustion engine, with the support surface formed in the receiving bore. The clamping force presses the fuel injector against the support surface, sealing the receiving bore at this point so that the combustion chamber gas cannot escape between the wall of the receiving bore and the fuel injector. Drawing

[0018] The drawing shows various embodiments of the fuel injector assembly according to the invention.

[0019] Fig. 1 is a partially sectioned view of a fuel injector with a corresponding clamping device in the cylinder head of an internal combustion engine,

[0020] Fig. 2 is an enlargement of the section marked II in Fig. 1,

[0021] Fig. 3 shows another embodiment in the same representation as Fig. 2, as well as the

[0022] Fig. 4 and the

[0023] Fig. 5, showing further embodiments,

[0024] Fig. 6 shows a further embodiment with an alternatively designed jacket tube,

[0025] Fig. 7 the end of the jacket tube facing away from the combustion chamber to illustrate the clamping force,

[0026] Fig. 8 shows the section marked VIII in Fig. 7 in an enlarged view,

[0027] Fig. 9 a plan view of the top of the fuel injector with a clamping claw and

[0028] Fig. 10 shows a view of the clamping claw rotated relative to Fig. 9. Description of the embodiments

[0029] Fig. 1 shows a fuel injector arrangement according to the invention. The fuel injector 1 is arranged in a receiving bore 3 in a cylinder head 2 of an internal combustion engine, wherein the cylinder head 2 is shown here only on the left side of the fuel injector 1 for the sake of clarity, but which also continues on the right side. The fuel injector 1 rests with a sealing surface 19, with a combustion chamber seal 38 interposed, against an annular support surface 4 in the receiving bore 3, so that a seal is formed between the fuel injector 1 and the support surface 4. At the combustion chamber-side end of the fuel injector 1, an injection opening 9 is formed, through which the fuel from the fuel injector 1 can be introduced into a combustion chamber of the internal combustion engine.The fuel injector 1 has a housing 5 comprising an injector body 6 and a jacket tube 10, wherein the jacket tube 10 surrounds the injector body 6 over a large part of its length. A fuel inlet 8 is formed on the injector body 6 and is connected to a fuel line 7, via which gaseous or liquid fuel can be supplied to the fuel injector 1. The fuel introduced via the fuel inlet flows from the fuel inlet 8 through transverse bores 19 into an annular space 13 formed between the jacket tube 10 and the injector body 6, and through the annular space 13 further toward the injection opening 9.The fuel flows from the annular space 13 back into the injector body 6 via second transverse bores 22 and reaches a nozzle body 36 via fuel channels formed within the injector body 6 and not shown in the drawing. The nozzle body 36 is part of the injector body 6 and contains at least one injection opening 9. A movable valve element (not shown in the drawing) is arranged in the nozzle body 36, which opens the injection opening 9 at the desired time so that the fuel can be dispensed in a metered manner.

[0030] The jacket tube 10 rests at its end region facing the injection opening 9 with an end surface 18 on a pressure surface 16 of the injector body 6, as shown in Fig. 2 in an enlargement of the section designated II in Fig. 1. The seal between the jacket tube 10 and the injector body 2 is ensured by a sealing ring 25, which prevents fuel from escaping. At the opposite end of the jacket tube 10, between the injector body and the jacket tube 10, a seal 15 in the form of a sealing ring is arranged, which ensures the seal between the jacket tube 10 and the injector body 6 at this point, so that the annular space 13 is sealed off from the outside.

[0031] In order to fix the fuel injector 1 in the receiving bore 3 and ensure a secure seal on the support surface 4, a clamping force is applied to the end surface 14 of the casing tube 10 using a clamping device 30, which in the embodiment shown here takes the form of a clamping claw. This is fork-shaped and engages around the injector body 6, with the clamping surface 31 formed on the clamping claw 30 resting on the end surface 14 of the casing tube 10. The clamping claw 30 is clamped by a clamping screw 32, which engages in a screw hole 33 in the cylinder head. A yoke-shaped clamping claw is also possible, which is clamped in the cylinder head on each side with a clamping screw. Alternatively, the clamping device can also be designed in the form of a union nut, which is screwed into an internal thread in the receiving bore 3.The clamping force is directed via the jacket tube 10 to the pressure surface 16 and thus close to the combustion chamber end of the fuel injector 1. The area within the jacket tube 10 of the injector body 6 is not or hardly mechanically deformed by the clamping force, so that movable components arranged within this injector body are not impaired in their functionality by an elastic deformation of the injector body 6.

[0032] Fig. 3 shows a further alternative embodiment of the combustion chamber-side end of the jacket tube 10. Here, the jacket tube 10 has a conical end surface 18 that bears against a clamping ring 20 that forms the pressure surface 16. The clamping ring 20 is arranged in an annular groove 21 in the injector body 6 or nozzle body 36. For secure sealing, a sealing ring 25 is additionally arranged between the end region of the jacket tube 10 and the injector body 6. Fig. 4 shows a further exemplary embodiment in the same illustration as Fig. 3. The pressure surface 16 is arranged here on a union nut 23 that is screwed into an external thread 27 on the nozzle body 36. The union nut 23 is tightened against a counter surface 24 that is formed on a shoulder of the injector body 6 and is thus fixed.The jacket tube 10 rests with its end surface 18 on the pressure surface 16 of the union nut 23, whereby an additional sealing ring 25 is also provided between the jacket tube 10 and the nozzle body 36.

[0033] Fig. 5 shows a further exemplary embodiment in the same representation as Fig. 4. The pressure surface 16 is formed here on an outwardly projecting shoulder of the nozzle body 36, wherein the jacket tube 10 rests with its end surface 18 against this pressure surface 16. Since the shoulder projects radially relatively far outwards, the jacket tube 10 in this exemplary embodiment can be designed as a simple cylindrical tube which can be pushed over the injector body 6 from the inlet-side end of the fuel injector 1. In the exemplary embodiments in which the jacket tube 10 has a larger diameter at the inlet-side end of the fuel injector 1 than at the opposite end, the jacket tube is pushed over the fuel injector 1 from the side of the injection opening 9, wherein the pressure surface 16 must be subsequently formed or mounted, for example with the aid of a clamping ring 20 (see Fig.3) or by a shoulder 17, which is subsequently attached to the injector body 6 - for example by a welded connection.

[0034] Fig. 6 shows a further embodiment of the jacket tube 10. The jacket tube 10 here consists of a first partial jacket tube 110 and a second partial jacket tube 210. The second jacket tube 210 is screwed into an external thread 27' on the injector body 6 and the gap between the second partial jacket tube 210 and the injector body 6 is sealed by a sealing ring 25. The first partial jacket tube 110, which here is designed as a straight cylinder, is then pushed on from the end of the injector body 6 facing away from the combustion chamber and sealingly connected to the second partial jacket tube 210. The two partial jacket tubes 110, 210 rest against one another, with the sealing being achieved by an intermediate seal 26 in the form of a sealing ring. This allows the first partial jacket tube 110 to be pushed on as a straight circular cylinder from the fuel inlet side, which facilitates assembly within the cylinder head.

[0035] Fig. 7 shows the end of the jacket tube 10 and the injector body 6 facing away from the combustion chamber. The clamping force F is applied to the jacket tube 10 with the interposition of a sleeve 28. The end surface 18 of the jacket tube 10 is spherical or conical and designed with a radius R. The end face 29 of the sleeve 28 is conical, so that a radially inward force is exerted on the jacket tube 10 by the sleeve 28. This reduces the gap 35 between the jacket tube 10 and the injector body 6 and improves the fixation at this point between the jacket tube 10 and the injector body 6. The clamping force F on the sleeve 28 can also be applied by a clamping claw. For clarity, Fig. 8 shows an enlargement of the section labeled VIII in Fig. 7.

[0036] Fig. 9 shows a clamping device 30 in the form of a clamping claw, as already shown in Fig. 1, wherein here a plan view of the upper part of the fuel injector 1, i.e. the part facing away from the combustion chamber, is shown. The clamping claw 30 is fork-shaped and engages around the injector body 6 so that a clamping force can be exerted on the casing tube 10 or on the sleeve 28, if one is provided. The clamping claw 30 is clamped by means of a clamping screw 32 which engages in a corresponding thread in the cylinder head, and thus transfers the clamping force to the fuel injector 1. Fig. 10 shows another illustration of the clamping claw 30 in a perspective view. The clamping claw 30 has a clamping surface 31 which rests on the fuel injector or on the casing tube 10 in the assembly position.The clamping surface 31 can be bevelled, as can the end face 29 of the sleeve 28, so that an inwardly directed force is exerted directly on the casing tube 10.

Claims

Claims 1. A fuel injector assembly for mounting a fuel injector (1) in an internal combustion engine, wherein the fuel injector (1) is designed for the metered delivery of liquid or gaseous fuel and has a housing (5) comprising an injector body (6) and a jacket tube (10) surrounding the injector body (6), wherein the injector body (6) has a fuel inlet (8) and an injection opening (9) for delivering the fuel, and wherein an annular gap (13) is formed between the jacket tube (10) and the injector body (6), which forms a fuel flow path, and having a clamping device (30) by which a clamping force (F) is exerted on the fuel injector (1), which presses the fuel injector (1) against a support surface (4) in the internal combustion engine, characterized in that the clamping device (30) exerts the clamping force at least indirectly on the jacket tube (10).wherein the jacket tube (10) is supported with an end surface (14) facing the injection opening (9) on a pressure surface (16) on the injector body (6), 2. Fuel injector arrangement according to claim 1, characterized in that the clamping device (30) exerts the clamping force (F) on the end of the casing tube (10) facing away from the pressure surface (16).

3. Fuel injector arrangement according to claim 1 or 2, characterized in that the injector body (6) comprises a nozzle body (36) in which the injection opening (9) is formed and which forms the combustion chamber-side end section of the injector body (6), wherein the pressure surface (16) is formed on the nozzle body (36).

4. Fuel injector arrangement according to one of claims (1) to (3), characterized in that the pressure surface (16) is formed on a shoulder (17) on the injector body (6).

5. Fuel injector arrangement according to one of claims 1 to 3, characterized in that the pressure surface (16) is formed on a snap ring (20) which engages in an annular groove (21) on the injector body (6).

6. Fuel injector arrangement according to one of claims 1 to 3, characterized in that the pressure surface (16) is formed on a union nut (23) which is screwed into an external thread (27) formed on the injector body (6).

7. Fuel injector arrangement according to one of claims 1 to 6, characterized in that the jacket tube (10) comprises two partial jacket tubes (110; 210) which adjoin one another in the longitudinal direction, wherein an intermediate seal (26) is arranged between the two partial jacket tubes (110; 210).

8. Fuel injector arrangement according to one of claims 1 to 7, characterized in that a seal (15) is arranged between the end region of the casing tube (10) facing away from the pressure surface (16) and the injector body (6).

9. Fuel injector arrangement according to one of claims 1 to 8, characterized in that the end surface (14) of the casing tube (10) facing away from the pressure surface (16) is spherical or conical.

10. Fuel injector arrangement according to claim 9, characterized in that a sleeve (28) surrounding the injector body (6) is arranged between the clamping device (30) and the casing tube (10), which sleeve is pressed by the clamping device (30) against the end of the casing tube (10) facing away from the pressure surface (16).

11. Fuel injector assembly according to claim 10, characterized in that the end face (29) of the sleeve (28) that interacts with the end face (14) is beveled, so that an inwardly directed force acts on the casing tube (10).

12. Fuel injector assembly according to one of claims 1 to 11, characterized in that the clamping device (30) is a clamping claw.

13. Fuel injector arrangement according to claim 12, characterized in that the clamping claw (30) is fork-shaped and engages around the injector body (6), wherein an inwardly directed clamping surface (31) is formed on the clamping claw (30).

14. Fuel injector arrangement according to one of claims 1 to 13, characterized in that the fuel injector (1) is arranged in a receiving bore (3) of the internal combustion engine, wherein the support surface (4) is formed in the receiving bore (3).

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