Fuel injector device for mounting a fuel injector in an internal combustion engine

Abstract

[Solution] A fuel injector device for mounting a fuel injector (1) in an internal combustion engine, the fuel injector (1) having a housing (5) configured to dispense and discharge a liquid or gaseous fuel and including an injector body (6) and an outer jacket tube (10) surrounding the injector body (6), the injector body (6) having a fuel supply portion (8) and an injection hole (9) for discharging the fuel. An annular gap (13) is formed between the outer jacket tube (10) and the injector body (6) to form a fuel flow path. A clamping device (30) applies a clamping force (F) to the fuel injector (1) to press the fuel injector (1) against a mounting surface (4) within the internal combustion engine, and the clamping device (30) applies the clamping force at least indirectly to the outer jacket tube (10). The outer jacket pipe (10) is supported by a pressure surface (16) of the injector body (6) at its end surface (14) on the injection hole (9) side.

Description

[Technical Field]

[0001] The present invention relates to a fuel injector device for mounting a fuel injector in an internal combustion engine, the fuel injector being used to dispense a preferably liquid or gaseous fuel into a combustion chamber of the internal combustion engine. [Background technology]

[0002] In direct-injection internal combustion engines, fuel, which can be gaseous or liquid, is introduced directly into the combustion chamber of the engine. The fuel is introduced into the combustion chamber at the right time and at high pressure using a fuel injector, which is usually located in the cylinder head of the engine. The fuel-air mixture is then ignited, usually by spark ignition using a spark plug, or by compression of the combustion chamber air alone (autoignition), as in diesel engines. Since the fuel injector protrudes into the combustion chamber, it is exposed to the pressure therein. Therefore, its installation in the cylinder head must meet the following requirements: On the one hand, the fuel injector must withstand the pressure generated by combustion and the corresponding temperature in the combustion chamber. On the other hand, the combustion chamber gases in the combustion chamber must be sealed so that they do not reach the outside between the fuel injector and the bore wall.

[0003] For this purpose, the fuel injector is fixed to the bore in the cylinder head using a clamping device, at least one clamping claw, or a fastening screw. Such an arrangement is known, for example, from Patent Document 1. In this case, the clamping claw is forked and grips the injector so that it surrounds it. By tightening the clamping screw, the clamping claw is pressed against the injector, thus forcing it into the receiving bore in the cylinder head against the corresponding sealing surface. Because the force required for sealing is relatively large, the force of the claw causes elastic deformation of the injector's force-bearing parts, affecting the predetermined part pairing. This deformation is usually not a problem for injectors used to inject liquid fuel into the combustion chamber of an internal combustion engine. Here, the flow cross section inside the injector body is relatively small, and therefore the injector is designed quite robust, so the force of the claw does not cause significant deformation.

[0004] Injectors for injecting or injecting alternative fuels, particularly gaseous fuels, require significantly larger flow cross sections within the injector due to the extremely low energy density of the fuel. Furthermore, fuel pressure is significantly lower than with liquid fuels, and correspondingly large fuel flow rates can only be achieved with larger flow cross sections. Due to limited installation space within the cylinder head, the injector housings of these fuel injectors are relatively thin-walled. However, the required pawl force remains the same, which results in significantly stronger deformations of the fuel injector, changing functional design criteria within the injector, such as the valve stroke or residual air gap. The diffusion of the pawl force from one injector to another must also be taken into account. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] DE 10155678 Summary of the Invention

[0006] The fuel injector device according to the present invention for mounting a fuel injector in an internal combustion engine has the advantage that, despite a relatively large through-flow cross section for fuel, the fuel injector can be mounted securely in the engine with a high force of the claws without the gripping of the claws impairing the function of the fuel injector. To this end, the fuel injector device has a fuel injector for dispensing a metered amount of liquid or gaseous fuel and a housing including an injector body and a jacket tube surrounding the injector body. The injector body has a fuel supply and an injection hole for discharging the fuel, with an annular gap between the jacket tube and the injector body forming a fuel flow path. A clamping device is also provided for applying a clamping force to the fuel injector, pressing it against a mounting surface in the internal combustion engine. The clamping device applies the clamping force at least indirectly to the jacket tube, with the jacket tube being supported at its end face facing the injection hole by a pressure surface of the injector body.

[0007] The pressure surface can be formed at any height on the injector body, so that the force of the claw can be applied relatively close to the combustion chamber, i.e., near the combustion chamber-side end region of the injector, via the jacket tube surrounding the injector body. Therefore, the portion of the fuel injector surrounded by the jacket tube is not obstructed by the clamping device, and as a result, no technical problems arise in this region of the fuel injector due to deformation. In this way, the fuel injector can be reliably and securely fixed in the cylinder head bore of an internal combustion engine, despite a relatively large flow cross section, such as is required for gaseous fuels in particular.

[0008] In a first advantageous embodiment, the clamping force is applied by the clamping device to the end of the jacket tube facing away from the pressure surface, which end is easily accessible so that already known claw or clamping devices can be used.

[0009] In a further advantageous embodiment, the injector body includes a nozzle body, in which the injection holes are formed and which forms the end portion of the body facing the combustion chamber, and in which the pressure surface is formed on the nozzle body. This allows the application point of the clamping force on the fuel injector to be moved away from the combustion chamber, which reduces deformation of the injector body. In particular, the nozzle body forming the end portion of the injector body facing the combustion chamber provides a favorable location for the pressure surface.

[0010] In a further advantageous embodiment, the pressure surface is formed on the injector body. This can be easily formed, for example, by a turning process. In an equally advantageous embodiment, the pressure surface can be formed on a snap ring that engages in an annular groove in the injector body. This snap ring is reliable and can be easily implemented on a variety of injector bodies.

[0011] In a further advantageous embodiment, the pressure surface is formed on a sleeve nut that is screwed onto an external thread formed on the injector body. In this way, the pressure surface is easily created on the injector body. The sleeve nut can be positioned by providing an external thread at any location on the injector body.

[0012] In a further advantageous configuration, the jacket pipe is formed from two partial jacket pipes that abut each other longitudinally, with an intermediate seal disposed between the two partial jacket pipes. This arrangement has the advantage that the partial jacket pipe on the combustion chamber side can be fixedly connected to the injector body, for example, by means of a screw thread. The second partial jacket pipe can be inserted from the top side of the injector, i.e., from the side opposite the injection holes. This facilitates assembly and thus installation of the fuel injector device in an internal combustion engine.

[0013] 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, so that the annular chamber formed between the jacket tube and the injector body can be reliably sealed even when a clamping force is applied to the jacket tube.

[0014] In a further preferred embodiment, the end face of the jacket tube facing away from the pressure surface is ball-shaped or conical. This can be combined in a preferred embodiment with an auxiliary sleeve arranged between the clamping device and the jacket tube. As the clamping device presses the sleeve, which in turn presses the jacket tube, the sleeve exerts an inward force on the end face of the jacket tube, thereby preventing or at least reducing relative movement of the injector within the jacket tube. In this case, the end face of the sleeve that cooperates with the end face of the jacket tube is preferably ball-shaped or conical, so that the inward force acting on the end face of the jacket tube is increased.

[0015] In a further advantageous embodiment, the clamping device is configured as a clamping claw. The clamping claw has the advantage that it can be pressed laterally via the injector, and for this purpose, the clamping claw is preferably forked. This means that a large clamping force can be applied to the end area of ​​the fuel injector facing away from the combustion chamber without having to be modified and without the end area remaining freely accessible for further connection. Advantageously, the clamping claw has an inwardly directed clamping surface that applies an inward force to the jacket tube, bringing it into contact with the injector body.

[0016] In a further advantageous embodiment, the fuel injector is arranged in a receiving bore of an internal combustion engine, with the support surface formed in the receiving bore, and the clamping force presses the fuel injector against the support surface, sealing the receiving bore at this point so that combustion chamber gas cannot escape between the wall of the receiving bore and the fuel injector.

[0017] The drawings illustrate various embodiments of a fuel injector device according to the present invention. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a partial cross-sectional view of a fuel injector with a corresponding clamping device in a cylinder head of an internal combustion engine; [Figure 2] FIG. 2 is an enlarged view of a portion indicated by II in FIG. [Figure 3] FIG. 3 is a diagram showing another embodiment in the same view as FIG. 2. [Figure 4] [Figure 5] FIG. 10 shows another embodiment. [Figure 6] 10A and 10B show other embodiments with alternative jacket tube configurations. [Figure 7] FIG. 1 shows the end of the jacket tube facing away from the combustion chamber to illustrate the clamping force. [Figure 8] FIG. 8 is an enlarged view of a portion indicated by VIII in FIG. 7. [Figure 9] FIG. 2 is a plan view of the upper side of a fuel injector with clamping pawls. [Figure 10] FIG. 10 is a view showing the clamping claw rotated compared to FIG. 9; DETAILED DESCRIPTION OF THE INVENTION

[0019] FIG. 1 illustrates a fuel injector device according to the present invention. The fuel injector 1 is disposed in a receiving bore 3 in a cylinder head 2 of an internal combustion engine. The cylinder head 2 continues to the right, although only the left side of the fuel injector 1 is shown for clarity. The fuel injector 1 rests against a ring-shaped support surface 4 in the receiving bore 3 with a sealing surface 19 beneath an intermediate combustion chamber seal 38, thereby forming a seal between the fuel injector 1 and the support surface 4. The combustion chamber end of the fuel injector 1 is formed with an injection hole 9 through which fuel can be introduced from the fuel injector 1 into the combustion chamber of the internal combustion engine. The fuel injector 1 has a housing 5 containing an injector body 6 and an outer tube 10, which surrounds the injector body 6 over most of its length. The injector body 6 is formed with a fuel supply 8, which is connected to a fuel pipe 7, through which gaseous or liquid fuel can be supplied to the fuel injector 1. Fuel taken in via the fuel supply 8 flows from the fuel supply 8 through a plurality of transverse holes 19 into the annular chamber 13 formed between the jacket tube 10 and the injector body 6, and then through the annular chamber 13 toward the injection holes 9. From the annular chamber 13, the fuel flows again via a plurality of second transverse holes 22 into the injector body 6 and through a plurality of fuel passages formed in the injector body 6 and not shown in the drawings to a nozzle body 36, which is part of the injector body 6 and in which at least one injection hole 9 is formed. A movable valve element, not shown in the drawings, is arranged in the nozzle body 36 and opens the injection holes 9 at the desired time, thereby discharging the fuel in a metered manner.

[0020] 1, the jacket tube 10 rests with its end face 18 on the pressure surface 16 of the injector body 6 in its end region facing the injection holes 9, as shown in Fig. 2 on an enlarged scale in the area designated II in Fig. 1. The seal between the jacket tube 10 and the injector body 2 is ensured by a packing ring 25 that prevents fuel from escaping. At the opposite end of the jacket tube 10, between the injector body and the jacket tube 10, a packing 15 in the form of a packing ring is arranged, which ensures a seal between the jacket tube 10 and the injector body 6 at this point, so that the annular chamber 13 is sealed off from the outside.

[0021] To secure the fuel injector 1 in the receiving bore 3 and ensure a tight seal at the seating surface 4, a clamping force is applied to the end face 14 of the jacket tube 10 by means of a clamping device 30, which in the illustrated embodiment takes the form of clamping claws. The clamping claws are forked and grip the injector body 6 so that a clamping surface 31 formed on the clamping claws rests against the end face 14 of the jacket tube 10. The clamping claws 30 are clamped by means of a clamping screw 32 that engages with a threaded hole 33 in the cylinder head. Yoke-shaped clamping claws that are clamped into the cylinder head using clamping screws on both sides are also possible. Alternatively, the clamping device may take the form of a sleeve nut that screws into the internal thread of the receiving bore 3. The clamping force is conducted via the jacket tube 10 to the pressure surface 16 and thus to the vicinity of the combustion chamber end of the fuel injector 1. The area of ​​the injector body 6 within the outer tube 10 is not or only slightly deformed mechanically by the clamping force, so that the functionality of moving components arranged inside the fuel injector is not hindered by the elastic deformation of the injector body 6.

[0022] 3 shows another alternative configuration of the end of the jacket tube 10 facing the combustion chamber. Here, the jacket tube 10 has a conical end face 18 that rests against a clamping ring 20 forming the pressure surface 16. The clamping ring 20 is arranged in an annular groove 21 in the injector body 6 or in the nozzle body 36. For reliable sealing, a packing ring 25 is additionally arranged between the end region of the jacket tube 10 and the injector body 6.

[0023] Figure 4 shows another embodiment in the same view as Figure 3. Here, the pressure surface 16 is arranged on a sleeve nut 23 which is screwed onto an external thread 27 on a nozzle body 36. The sleeve nut 23 is fixed and cannot rotate against a locking surface 24 formed on a step in the injector body 6. The jacket tube 10 rests with its end face 18 against the pressure surface 16 of the sleeve nut 23, and here too an additional packing ring 25 is provided between the jacket tube 10 and the nozzle body 36.

[0024] Figure 5 shows another embodiment in the same view as Figure 4. Here, the pressure surface 16 is formed on an outwardly projecting step of the nozzle body 36, against which the jacket tube 10 rests with its end face 18. Because the step projects radially outward relatively far, in this embodiment the jacket tube 10 can be formed as a simple cylindrical tube that can be moved from the supply end of the fuel injector 1 through the injector body 6. In embodiments in which the jacket tube 10 has a larger diameter at the supply end of the fuel injector 1 than at the opposite end, the jacket tube must be moved through the fuel injector 1 from the injection hole 9 side, and the pressure surface 16 must be additionally formed or attached, for example by means of a clamping ring 20 (see Figure 3) or by means of a step 17 that is additionally fixed to the injector body 6 (for example by welding).

[0025] FIG. 6 shows another embodiment of the jacket pipe 10. Here, the jacket pipe 10 consists of a first partial jacket pipe 110 and a second partial jacket pipe 210. The second partial jacket pipe 210 is screwed onto the external thread 27' of the injector body 6, and the gap between the second partial jacket pipe 210 and the injector body 6 is sealed by a packing ring 25. The first partial jacket pipe 110, here configured as a straight cylinder, is then slid onto the end of the injector body 6 facing away from the combustion chamber and sealed to the second partial jacket pipe 210. The two partial jacket pipes 110, 210 abut against each other, and the seal is achieved by an intermediate packing 26 in the form of a packing ring. This allows the first partial jacket pipe 110, configured as a straight cylinder, to be slid onto the fuel supply side, which facilitates installation inside the cylinder head.

[0026] FIG. 7 again shows the ends of the jacket tube 10 and the injector body 6 facing away from the combustion chamber. Here, a clamping force F acts on the jacket tube 10 via a sleeve 28 as an intermediate layer. The end face 18 of the jacket tube 10 is ball-shaped or conically shaped and has a radius R. The end face 29 of the sleeve 28 is conically shaped, so that the sleeve 28 exerts a radially inward force on the jacket tube 10. This narrows the gap 35 between the jacket tube 10 and the injector body 6, improving the fixation between the jacket tube 10 and the injector body 6 at this point. The clamping force F on the sleeve 28 can also be exerted by clamping claws. For clarity, FIG. 8 shows an enlarged view of the area designated VIII in FIG. 7.

[0027] FIG. 9 shows a clamping device 30 in the form of clamping claws, as already shown in FIG. 1, in a plan view of the upper part of the fuel injector 1, i.e., the part facing away from the fuel chamber. The clamping claws 30 are forked and grip the injector body 6 so that a clamping force can be applied to the jacket tube 10 or sleeve 28 (if such is provided). The clamping claws 30 are clamped via a clamping screw 32 that engages with a corresponding thread in the cylinder head, thus transmitting the clamping force to the fuel injector 1. For this purpose, FIG. 10 again shows the clamping claws 30 in a perspective view. The clamping claws 30 have clamping surfaces 31 that rest against the fuel injector or jacket tube 10 in the mounted position. The clamping surfaces 31, like the end faces 29 of the sleeve 28, can be inclined, so that the inwardly directed force acts directly on the jacket tube 10. [Explanation of symbols]

[0028] 1 fuel injector 3 Receptor hole 4. Placement surface 5. Housing 6 Injector body 8 Fuel supply section 9 injection hole 10 Jacket tube 13 Annular gap 14 End face of outer jacket pipe 15 Gasket 16 Pressure Surface 17 Step section 20 Snap ring, fastening ring 21 Annular groove 23 Sleeve nut 26 Intermediate packing 27 Male thread 28 sleeve 29 Sleeve end face 30 Clamping claw (clamping device) 31 Fastening surface 36 Nozzle body 110 First partial outer jacket tube 210 Second partial outer jacket tube F Tightening force

Claims

1. A fuel injector device for mounting a fuel injector (1) in an internal combustion engine, the fuel injector (1) having a housing (5) configured to dispense and discharge a liquid or gaseous fuel and including an injector body (6) and an outer jacket tube (10) surrounding the injector body (6), the injector body (6) having a fuel supply portion (8) and an injection hole (9) for discharging the fuel, an annular gap (13) forming a fuel flow path is formed between the outer jacket tube (10) and the injector body (6), the fuel injector device further comprising a clamping device (30) for applying a clamping force (F) to the fuel injector (1), the clamping device (30) pressing the fuel injector (1) against a mounting surface (4) in the internal combustion engine, 1. A fuel injector device according to claim 1, wherein the clamping device (30) applies the clamping force at least indirectly to the outer jacket pipe (10), and the outer jacket pipe (10) is supported by a pressure surface (16) of the injector body (6) at its end surface (14) on the injection hole (9) side.

2. 2. The fuel injector device according to claim 1, wherein the clamping device (30) applies the clamping force (F) to an end of the jacket tube (10) opposite the pressure surface (16).

3. 3. The fuel injector device according to claim 1, wherein the injector body includes a nozzle body, the injection holes are formed in the nozzle body, the nozzle body forms an end portion of the injector body on a combustion chamber side, and the pressure surface is formed on the nozzle body.

4. 4. The fuel injector device according to claim 1, wherein the pressure surface (16) is formed on a step (17) provided on the injector body (6).

5. 4. The fuel injector device according to claim 1, wherein the pressure surface (16) is formed on a snap ring (20) that engages with an annular groove (21) provided in the injector body (6).

6. 4. The fuel injector device according to claim 1, wherein the pressure surface (16) is formed on a sleeve nut (23) that is screwed onto an external thread (27) formed on the injector body (6).

7. 7. A fuel injector device according to claim 1, wherein the outer jacket pipe (10) comprises two partial jacket pipes (110, 210) abutting each other in the longitudinal direction, and an intermediate packing (26) is arranged between the two partial jacket pipes (110, 210).

8. 8. The fuel injector device according to claim 1, wherein a packing (15) is arranged between the end region of the jacket pipe (10) facing away from the pressure surface (16) and the injector body (6).

9. 9. A fuel injector device according to claim 1, wherein the end face (14) of the jacket pipe (10) facing away from the pressure surface (16) is ball-shaped or conically shaped.

10. 10. The fuel injector device according to claim 9, wherein a sleeve (28) surrounding the injector body (6) is arranged between the clamping device (30) and the jacket pipe (10), and the sleeve (28) is pressed by the clamping device (30) against the end of the jacket pipe (10) facing away from the pressure surface (16).

11. 11. A fuel injector device according to claim 10, characterized in that the end face (29) of the sleeve (28) cooperating with the end face (14) is inclined, so that an inwardly directed force acts on the jacket tube (10).

12. 12. A fuel injector arrangement according to any one of claims 1 to 11, characterized in that the clamping device (30) is a clamping claw.

13. 13. The fuel injector device according to claim 12, wherein the clamping claws (30) are forked to surround and grip the injector body (6), and the clamping claws (30) are formed with clamping surfaces (31) directed inward.

14. 14. The fuel injector device according to claim 1, wherein the fuel injector (1) is arranged in a receiving bore (3) of the internal combustion engine, and the mounting surface (4) is formed in the receiving bore (3).

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