Fuel injector assembly for assembling fuel injector in internal combustion engine

Abstract

The invention relates to a fuel injector assembly for assembling a fuel injector (1) in an internal combustion engine, the fuel injector (1) being designed to dispense liquid or gaseous fuel in a metered manner and having a housing (5) comprising an injector body (6) and a sleeve (10) surrounding the injector body (6), the injector body (6) has a fuel inlet (8) and an injection opening (9) for discharging fuel. An annular gap (13) is formed between the sleeve (10) and the injector body (6), which annular gap forms a fuel flow path. A clamping device (30) for applying a clamping force (F) to the fuel injector (1) presses the fuel injector (1) against a bearing surface (4) in the internal combustion engine, the clamping device (30) applying the clamping force at least indirectly to the sleeve (10). The sleeve (10) is supported with an end face (14) facing the injection opening (9) on a pressing face (16) on the injector body (6).

Description

Field of the Invention

[0001] The invention relates to a fuel injector assembly for fitting a fuel injector in an internal combustion engine, wherein the fuel injector is preferably adapted to meteringly introduce (eindosieren) liquid or gaseous fuel into the combustion chamber of the internal combustion engine. Background Art

[0002] In a direct injection internal combustion engine, fuel, which can be gaseous or liquid, is directly introduced into the combustion chamber of the internal combustion engine. Here, a fuel injector, which is usually arranged in the cylinder head of the internal combustion engine, introduces fuel into the combustion chamber at the correct point in time under high pressure. Subsequently, the fuel-air mixture is either ignited by an external ignition source, in most cases by means of a spark plug, or is ignited (self-ignited) only by compressing the combustion chamber air according to the diesel engine principle. Since the fuel injector projects into the combustion chamber, the fuel injector is subjected to the pressure in the combustion chamber. Therefore, the fitting in the cylinder head must meet the following requirements: on the one hand, the fuel injector must be able to withstand the pressure generated by combustion and the corresponding temperature in the combustion chamber. On the other hand, the combustion chamber gas in the combustion chamber must be sealed so as to prevent these combustion chamber gases from leaking out between the fuel injector and the hole wall.

[0003] For this purpose, the fuel injector is fixed in a hole in the cylinder head by means of a clamping device, in most cases a clamping clip or a fixing bolt. For example, such an assembly is known from DE10155678A1. Here, the clamping clip is fork-shaped and surrounds the injector. By tightening the clamping bolt, the clamping clip is pressed against the injector and thus presses it into the receiving hole in the cylinder head, against the corresponding sealing surface. Since the force required for sealing is relatively high, the clamping clip force causes elastic deformation of the force-transmitting components of the injector and affects the previously adjusted component pairing. In an injector such as for injecting liquid fuel into the combustion chamber of an internal combustion engine, this deformation is usually insignificant. Here, the flow cross-section within the injector body is relatively small, and thus the injector is constructed quite robustly so that the clamping clip force does not cause significant deformation.

[0004] In an injector for injecting or blowing in alternative fuels, especially in the case of gaseous fuels, a significantly larger flow cross-section is required in the injector because the energy density of these fuels is significantly lower. In addition, the fuel pressure is much lower compared to liquid fuels, and only with a large flow cross-section can a correspondingly large fuel flow rate be achieved. Due to the limited installation space in the cylinder head, the injector housing of these fuel injectors is configured relatively thin-walled. However, the required clamping force remains constant, so that due to the clamping force, the fuel injector will be deformed significantly more strongly, resulting in a change in the set functional dimensions in the injector, such as the valve stroke or the remaining air gap. In addition, the deviation of the clamping force between different injectors must also be considered. Summary of the Invention

[0005] A fuel injector assembly for assembling a fuel injector in an internal combustion engine according to the present invention has the following advantages: Even if the flow cross-section for the fuel is relatively large, the fuel injector can be reliably assembled in the internal combustion engine with a high clamping force without impairing the functional mode of the fuel injector due to clamping. For this purpose, the fuel injector assembly has a fuel injector for metering and outputting liquid or gaseous fuel, wherein the fuel injector has a housing that includes an injector body and a sleeve surrounding the injector body. The injector body has a fuel inlet and an injection opening for outputting fuel, wherein an annular gap is formed between the sleeve and the injector body, and this annular gap forms a fuel flow path. In addition, there is a clamping device that applies a clamping force to the fuel injector and presses the fuel injector against a support surface in the internal combustion engine. The clamping device applies the clamping force at least indirectly to the sleeve, wherein the sleeve has its end face facing the injection opening supported on the pressing surface of the injector body.

[0006] The pressing surface can be configured at any height of the injector body, so that the clamping force can be applied relatively close to the combustion chamber via the sleeve surrounding the injector body, that is, close to the end region of the injector facing the combustion chamber. Thus, the section of the fuel injector surrounded by the sleeve will not be damaged by the clamping device, so that no technical problems caused by deformation will occur in this area of the fuel injector. Therefore, even with a relatively large flow cross-section (which is especially necessary for gaseous fuels), the fuel injector can be reliably and safely fastened in the cylinder head bore of the internal combustion engine.

[0007] In a first advantageous configuration, the clamping force is applied by the clamping device to the end of the sleeve facing the pressing surface. This end is easily accessible, so that known clamping devices or clamping means can be used.

[0008] In another advantageous configuration, the injector body includes a nozzle body in which an injection opening is configured, and the nozzle body forms the combustion chamber side end section of the injector body, wherein a pressing surface is configured on the nozzle body. Thus, the clamping force is applied far in the direction of the combustion chamber to the fuel injector, which minimizes the deformation of the injector body. In particular, the nozzle body forming the combustion chamber side end of the injector body provides a favorable location for the pressing surface.

[0009] In another advantageous configuration, the pressing surface is configured on the injector body. For example, the pressing surface can be easily manufactured by a turning process. Also, in an advantageous configuration, the pressing surface can be configured on a snap ring that is fitted into an annular groove on the injector body. Such a snap ring has been proven and can be easily used on different injector bodies.

[0010] In another advantageous configuration, the pressing surface is configured on a lock nut that is screwed into an external thread configured on the injector body. Thus, the pressing surface can be realized on the injector body in a simple manner. By providing the external thread, the lock nut can be placed at any location on the injector body.

[0011] In another advantageous configuration, the sleeve is composed of two partial sleeves that are adjacent to each other in the longitudinal direction, wherein an intermediate seal is arranged between the two partial sleeves. The advantage of this arrangement is that one of the partial sleeves facing the combustion chamber can be firmly connected to the injector body, for example, by means of a thread. The second partial sleeve can be inserted from above, i.e., from the side of the injector facing away from the injection opening. This simplifies the assembly and maintenance of the fuel injector assembly in the internal combustion engine.

[0012] In another advantageous configuration, a seal is arranged between the end region of the sleeve facing away from the pressing surface and the injector body. Thereby, even when a clamping force is applied to the sleeve, the annular space formed between the sleeve and the injector body can be reliably sealed.

[0013] In another advantageous configuration, the end face of the sleeve facing away from the pressing surface is configured spherically or conically. In an advantageous configuration, this can be combined with an additional sleeve that is arranged between the clamping device and the sleeve. Since the clamping device presses against the sleeve, and the sleeve in turn presses against the sleeve, the sleeve applies an inwardly directed force to the end face of the sleeve, thereby preventing, or at least reducing, the relative movement of the injector in the sleeve. Here, in an advantageous manner, the end face of the sleeve that interacts with the end face of the sleeve is configured spherically or conically, thereby increasing the inwardly directed force applied to the end face of the sleeve.

[0014] In another advantageous configuration, the clamping device is configured as a clamping clip. The advantage of a clamping clip is that it can be slipped laterally onto the injector, for which purpose it is preferably configured in a fork-shaped manner. Thus, a high clamping force can be applied without modifying the end region of the fuel injector facing away from the combustion chamber, and this end region remains freely accessible for other attachments. Here, advantageously, an inwardly directed clamping surface is configured on the clamping clip, which exerts an inwardly directed force on the sleeve such that the sleeve contacts the injector body.

[0015] In another advantageous configuration, the fuel injector is arranged in a receiving bore of an internal combustion engine, wherein a bearing surface is configured in the receiving bore. By means of the clamping force, the fuel injector is pressed against the bearing surface and seals the receiving bore at this point, so that combustion chamber gases cannot escape between the wall of the receiving bore and the fuel injector. Description of the Drawings

[0016] Different embodiments of a fuel injector assembly according to the invention are shown in the drawings. The drawings show:

[0017] Figure 1 A partial cross-sectional view of a fuel injector with a corresponding clamping device in a cylinder head of an internal combustion engine;

[0018] Figure 2 Showing Figure 1 An enlarged view of the detail marked II in;

[0019] Figure 3 In the same illustration as Figure 2 Another embodiment is shown;

[0020] Figure 4 And Figure 5 Further embodiments are shown;

[0021] Figure 6 Another embodiment is shown, which has an alternatively configured sleeve;

[0022] Figure 7 The end of the sleeve facing away from the combustion chamber is shown for illustration of the clamping force;

[0023] Figure 8 Showing Figure 7 An enlarged view of the detail marked VIII in;

[0024] Figure 9 A top view of the top surface of a fuel injector with a clamping clip;

[0025] Figure 10 Showing Figure 9 A view of the clamping clip rotated by an angle compared to Detailed Description

[0026] Figure 1 Shows a fuel injector assembly according to the present invention. The fuel injector 1 is arranged in the receiving hole 3 of the cylinder head 2 of an internal combustion engine, where, for clarity, only the left side of the fuel injector 1 is shown with respect to the cylinder head 2, which also continues on the right side. The fuel injector 1 abuts against the annular support surface 4 in the receiving hole 3 with a sealing surface 19 with a combustion chamber seal 38 placed in between, thereby forming a seal between the fuel injector 1 and the support surface 4. An injection opening 9 is constructed at the combustion chamber side end of the fuel injector 1, 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, which includes an injector body 6 and a sleeve 10, where the sleeve 10 surrounds the injector body 6 over most of its length. A fuel inlet 8 is constructed on the injector body 6, which is connected to a fuel line 7, through which gaseous or liquid fuel can be supplied to the fuel injector 1. The fuel introduced through the fuel inlet flows from the fuel inlet 8 through a transverse hole 19 into an annular space 13 formed between the sleeve 10 and the injector body 6 and continues to flow through this annular space 13 in the direction towards the injection opening 9. The fuel flows again from the annular space 13 through a second transverse hole 22 into the injector body 6 and enters a nozzle body 36 through a fuel passage (not shown in the figure) constructed within the injector body 6. The nozzle body is a part of the injector body 6 and at least one injection opening 9 is constructed in this nozzle body. A movable valve element (not shown in the figure) is arranged in the nozzle body 36, which opens the injection opening 9 at a desired time point, thereby enabling the fuel to be output in a metered manner.

[0027] The sleeve 10 abuts against the pressing surface 16 of the injector body 6 with an end surface 18 in its end region facing the injection opening 9, as Figure 2 shown in Figure 1 the enlarged partial view marked II. The seal between the sleeve 10 and the injector body 2 is ensured by a seal ring 25, which prevents the fuel from flowing out. At the opposite ends of the sleeve 10, a seal 15 in the form of a seal ring is arranged between the injector body and the sleeve 10, which ensures the seal between the sleeve 10 and the injector body 6 at this location, thereby sealing the annular space 13 outwards.

[0028] In order to fix the fuel injector 1 in the receiving bore 3 and ensure a reliable seal at the bearing surface 4, a clamping force is applied to the end face 14 of the sleeve 10 by means of a clamping device 30, which has the shape of a clamping collar in the embodiment shown here. The clamping collar is fork-shaped and surrounds the injector body 6, wherein the clamping surface 31 constructed on the clamping collar 30 bears on the end face 14 of the sleeve 10. The clamping collar 30 is clamped by a clamping bolt 32, which is inserted into a threaded bore 33 in the cylinder head. It is also possible to use an arcuate clamping collar, which is clamped in the cylinder head on both sides by one clamping bolt each. Alternatively, the clamping device can also be constructed in the form of a lock nut, which is screwed into an internal thread in the receiving bore 3. The clamping force is transmitted via the sleeve 10 to the pressing surface 16, thus close to the combustion chamber side end of the fuel injector 1. The region of the injector body 6 within the sleeve 10 does not or hardly undergoes mechanical deformation due to the clamping force, so that the movable components arranged within this injector body are not impaired in their function due to elastic deformation of the injector body 6.

[0029] Figure 3 Another alternative configuration of the combustion chamber side end of the sleeve 10 is shown. Here, the sleeve 10 has a conical end face 18, which abuts against a clamping ring 20 forming the pressing surface 16. Here, the clamping ring 20 is arranged in an annular groove 21 in the injector body 6 or the nozzle body 36. In order to ensure the seal, a sealing ring 25 is additionally arranged between the end region of the sleeve 10 and the injector body 6.

[0030] Figure 4 Shown in the same illustration as Figure 3 Another embodiment is shown. Here, the pressing surface 16 is arranged on a lock nut 23, which is screwed onto an external thread 27 on the nozzle body 36. The lock nut 23 is tightened here against an opposing surface 24 and is thus fixed, which opposing surface is constructed on a flange of the injector body 6. The sleeve 10 abuts with its end face 18 on the pressing surface 16 of the lock nut 23, wherein here, an additional sealing ring 25 is also provided between the sleeve 10 and the nozzle body 36.

[0031] Figure 5 Shown in the same illustration as Figure 4The same illustration shows another embodiment. Here, the extrusion surface 16 is configured on the outwardly protruding flange of the nozzle body 36, and the sleeve 10 abuts against the extrusion surface 16 with its end face 18. Since the flange protrudes relatively far outward in the radial direction, in this embodiment, the sleeve 10 can be configured as a simple cylindrical tube, which can be sleeved onto the injector body 6 starting from the inlet-side end of the fuel injector 1. In some embodiments, the diameter of the sleeve 10 at the inlet-side end of the fuel injector 1 is greater than its diameter at the opposite end. In these embodiments, the sleeve is sleeved onto the fuel injector 1 starting from one side of the injection opening 9, and the extrusion surface 16 must be formed or assembled afterwards, for example, by means of a clamping ring 20 (see Figure 3 ), or by means of a flange 17 that is fastened to the injector body 6 afterwards, for example, by a welded connection.

[0032] Figure 6 Another embodiment of the sleeve 10 is shown. Here, the sleeve 10 consists of a first partial sleeve 110 and a second partial sleeve 210. The second sleeve 210 is screwed into the external thread 27' on the injector body 6, and the gap between the second partial sleeve 210 and the injector body 6 is sealed by a sealing ring 25. The first partial sleeve 110, which is configured as a straight cylinder here, is then sleeved onto the end of the injector body 6 facing away from the combustion chamber and is sealingly connected to the second partial sleeve 210. Here, the two partial sleeves 110, 210 abut against each other, and the sealing is achieved by an intermediate seal 26 in the form of a sealing ring. Thus, the first partial sleeve 110 can be sleeved onto the fuel inlet side as a straight cylinder, which simplifies the assembly in the cylinder head.

[0033] Figure 7 The end of the sleeve 10 and the injector body 6 facing away from the combustion chamber are shown again. Here, with the sleeve 28 placed in the middle, a clamping force F is applied to the sleeve 10. The end face 18 of the sleeve 10 is configured spherically or conically and is configured with a radius R. The end face 29 of the sleeve 28 is configured conically, so that a radially inwardly directed force is applied to the sleeve 10 through the sleeve 28. Thereby, the gap 35 between the sleeve 10 and the injector body 6 is reduced, and the fixation at this location between the sleeve 10 and the injector body 6 is improved. The clamping force F applied to the sleeve 28 can also be applied by a clamping band. For a clearer illustration, Figure 8 shows Figure 7 an enlarged view of the partial view marked VIII.

[0034] Figure 9 shown in Figure 1A clamping device 30 in the form of a clamping clip as in [description], where a top view of the upper part of the fuel injector 1, i.e., the part facing away from the combustion chamber, is shown here. The clamping clip 30 is fork-shaped and surrounds the injector body 6 so that a clamping force can be applied to the sleeve 10 or the sleeve 28 (if provided). Here, the clamping clip 30 is clamped by a clamping bolt 32 screwed into a corresponding thread in the cylinder head and thus transfers the clamping force to the fuel injector 1. For this purpose, Figure 10 A view showing the clamping clip 30 again in perspective. The clamping clip 30 has a clamping surface 31 which, in the assembled position, abuts against the fuel injector or the sleeve 10. Here, the clamping surface 31 can be inclined like the end face 29 of the sleeve 28 so that the force directed inwards is directly applied to the sleeve 10.

Claims

1. A fuel injector assembly for fitting a fuel injector (1) in an internal combustion engine, wherein, the fuel injector (1) is configured to output liquid fuel or gaseous fuel in a metered manner and has a housing (5), the housing including an injector body (6) and a sleeve (10) surrounding the injector body (6), wherein the injector body (6) has a fuel inlet (8) and an injection opening (9) for outputting fuel, and wherein an annular gap (13) is formed between the sleeve (10) and the injector body (6), the annular gap forming a fuel flow path, and a clamping device (30) is provided, by which a clamping force (F) is applied to the fuel injector (1), the clamping force pressing the fuel injector (1) against a support surface (4) in the internal combustion engine. It is characterized in that, the clamping device (30) applies the clamping force at least indirectly to the sleeve (10), wherein the sleeve (10) is supported on a pressing surface (16) on the injector body (6) by an end face (14) facing the injection opening (9).

2. The fuel injector assembly according to claim 1, It is characterized in that, the clamping device (30) applies the clamping force (F) to an end of the sleeve (10) facing away from the pressing surface (16).

3. The fuel injector assembly according to claim 1 or 2, It is characterized in that, the injector body (6) includes a nozzle body (36), the injection opening (9) is configured in the nozzle body, and the nozzle body forms a combustion chamber side end section of the injector body (6), wherein the pressing surface (16) is configured on the nozzle body (36).

4. The fuel injector assembly according to any one of claims (1) to (3), It is characterized in that, the pressing surface (16) is configured on a flange (17) on the injector body (6).

5. The fuel injector assembly according to any one of claims 1 to 3, It is characterized in that, the pressing surface (16) is configured on a snap ring (20), the snap ring being fitted into an annular groove (21) on the injector body (6).

6. The fuel injector assembly according to any one of claims 1 to 3, It is characterized in that, the pressing surface (16) is configured on a lock nut (23), the lock nut being screwed into an external thread (27) configured on the injector body (6).

7. The fuel injector assembly according to any one of claims 1 to 6, It is characterized in that, the sleeve (10) includes two partial sleeves (110; 210), the two partial sleeves being adjacent to each other in the longitudinal direction, wherein an intermediate seal (26) is arranged between the two partial sleeves (110; 210).

8. The fuel injector assembly according to any one of claims 1 to 7, It is characterized in that, a seal (15) is arranged between an end region of the sleeve (10) facing away from the pressing surface (16) and the injector body (6).

9. The fuel injector assembly according to any one of claims 1 to 8, characterized in that, the end face (14) of the sleeve (10) facing away from the pressing surface (16) is configured spherically or conically.

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

11. The fuel injector assembly 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 sleeve (10).

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

13. The fuel injector assembly according to claim 12, characterized in that, the clamping band (30) is configured in a fork shape and surrounds the injector body (6), and an inwardly directed clamping surface (31) is formed on the clamping band (30).

14. The fuel injector assembly according to any one of claims 1 to 13, characterized in that, the fuel injector (1) is arranged in the receiving hole (3) of the internal combustion engine, and the supporting surface (4) is formed in the receiving hole (3).

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