Sealing ring for the arrangement of a fuel injector and method for assembly

Abstract

A sealing ring (20) for arranging a fuel injector (1) in a receptacle (8) of an internal combustion engine, wherein the sealing ring (20) has a central opening (21) for guiding the fuel injector (1) through and an at least substantially conical sealing surface (22) which, in the installed position in the internal combustion engine, faces the combustion chamber and bears against a conical contact surface (23) in the receptacle (8) of the internal combustion engine. The sealing surface (22) has an inner circumferential projection (24) and an outer circumferential projection (25) with which the sealing ring (20) bears against the contact surface (23). In the method for mounting a fuel injector (1) in an internal combustion engine, the fuel injector (1) is inserted into the receptacle (8), wherein the sealing ring (20) is arranged between a shoulder (17) of the fuel injector (1) and the conical contact surface (23).Subsequently, an axial clamping force is applied to the fuel injector (1), so that the sealing ring (20) with the two protrusions (24; 25) is pressed against the conical contact surface (23).

Description

[0001] The invention relates to a sealing ring for arranging a fuel injector in an internal combustion engine, and a method for assembling a fuel injector - in particular in an internal combustion engine - using such a sealing ring. State of the art

[0002] Fuel injectors for introducing fuel into the combustion chamber of an internal combustion engine are inserted into a receptacle in the engine, with the end of the fuel injector containing the injection orifices extending into the combustion chamber. The receptacle is, for example, a bore in the cylinder head. The fuel injector is axially clamped in the receptacle, for example by a screw device or a clamping jaw, so that it can withstand the combustion chamber pressure. To seal the gap between the fuel injector and the wall of the receptacle against the combustion chamber gases, it is known to arrange a sealing ring in the receptacle. Such a sealing ring is known, for example, from DE 10 2021 202 728 A1.

[0003] Sealing rings are used to create a seal between the combustion chamber and the fuel injector's installation space. These rings are pressed onto the fuel injector under friction. This has the advantage that the sealing ring does not remain in the cylinder head's installation space when the fuel injector is replaced and does not need to be removed separately. In smaller fuel injectors, these sealing rings are typically made of a copper-containing material, while in fuel injectors for large engines, they are usually made of soft, often corrosion-resistant steel materials.

[0004] However, conventional sealing rings are designed in such a way that while an axial seal is achieved, a radial gap remains between the sealing ring and the fuel injector. With alternative fuels, such as hydrogen, mixture preparation occurs very early in the charge motion, so that ignitable fuel gas is forced into these gaps and, after ignition, burns there. This creates delayed pressure spikes due to the combustion of these fuel gases in the gaps and an undesirable thermal energy input in this area. Advantages of the invention

[0005] The sealing ring according to the invention has the advantage that the fuel injector is sealed in a receptacle in both the axial and radial directions. The shape and position of the sealing ring reliably prevent combustion chamber gases from entering the space between the fuel injector and the receptacle. The sealing ring for mounting a fuel injector is installed in a receptacle of an internal combustion engine, with the sealing ring having a central opening for the passage of the fuel injector. The sealing ring has a sealing surface that is at least substantially conical, which, when installed in the internal combustion engine, faces the combustion chamber and bears against a conical contact surface in the receptacle of the internal combustion engine. The sealing surface has an inner circumferential projection and an outer circumferential projection, with which the sealing ring bears against the contact surface.

[0006] The design of the sealing ring, with its two circumferential protrusions, allows for individual definition and optimization of the radial and axial pressure. This ensures that the combustion chamber pressure is sealed via the axial pressure of the fuel injector in the receptacle, while simultaneously achieving plastic deformation of the sealing ring in the area of ​​the protrusions. This prevents a radial gap and keeps the pressure in the inner area of ​​the sealing ring low, thus preventing significant deformation of the fuel injector in the area of ​​the sealing ring and avoiding mechanical overload of the inner edge of the sealing ring.

[0007] In a first advantageous embodiment, the sealing ring has a pressure surface against which the fuel injector comes into contact in its installed position. The sealing ring is pressed against the conical contact surface by clamping the fuel injector in the receptacle, thus sealing the space between the fuel injector and the wall of the receptacle.

[0008] In a further advantageous embodiment, the raised section on the sealing ring is at least partially plastically deformed by the axial clamping of the fuel injector in the receptacle. This allows a seal, including a gas-tight seal, to be achieved on both raised sections, preventing combustion chamber gases from entering the gap between the fuel injector and the wall of the receptacle.

[0009] In a further advantageous embodiment, the conical sealing surface of the sealing ring is designed with an opening angle of 60° to 150°. The size of the opening angle allows the radial and axial pressure to be individually adjusted, thus optimizing the balance between sealing and the mechanical stress on fuel injectors.

[0010] In a further advantageous embodiment, the diameter of the inner circumferential projection is designed to be 1.05 to 1.2 times the inner diameter of the central opening of the sealing ring. The outer circumferential projection can advantageously be designed to have a diameter 1.3 to 1.4 times the inner diameter of the central opening. This results in optimal sealing while requiring minimal space.

[0011] In a method according to the invention for mounting a fuel injector in an internal combustion engine, the fuel injector is arranged in a receptacle in the internal combustion engine, wherein a conical contact surface is formed in the receptacle against which the fuel injector can be axially clamped. The sealing ring is pushed onto the fuel injector so that the sealing ring is arranged between a shoulder on the fuel injector and the conical contact surface. Subsequently, an axial clamping force is applied to the fuel injector so that the sealing ring with its two protrusions is pressed against the conical contact surface.

[0012] In a further advantageous embodiment of the method, the sealing ring is positively connected to the fuel injector. This allows the sealing ring to be removed from its housing when the fuel injector is disassembled, without requiring a separate step.

[0013] The clamping force can advantageously be chosen to be so large that the two protrusions are at least partially plastically deformed in order to achieve optimal sealing. drawing

[0014] The drawing shows a sealing ring according to the invention and an installation position of a fuel injector with such a sealing ring. Fig. 1 a longitudinal section through a fuel injector in an installation position in an internal combustion engine, wherein only the essential parts of the fuel injector near the combustion chamber are shown, Fig. 2 a cross-section through a sealing ring according to the invention, Fig. 3a the installation position of a sealing ring according to the invention before mounting it on the fuel injector and Fig. 3b the installation position of the sealing ring on the fuel injector. Description of the exemplary implementations

[0015] In Fig. Figure 1 shows a fuel injector 1 in its installed position in an internal combustion engine in longitudinal section, with only the part of the fuel injector 1 facing the combustion chamber shown. A cylinder head bore 18 is formed in a cylinder head 6 of an internal combustion engine, in which a receptacle 8 in the form of a water sleeve is arranged and screwed into a thread 16 at the combustion chamber-side end of the cylinder head bore 18. To cool the fuel injector 1, the water sleeve 8 can be cooled on its outer surface via corresponding supply lines in the cylinder head 6 with cooling water. The fuel injector 1 in the receptacle 8 has an injector body 2 with a pressure chamber 3 located therein and a nozzle body 4, which are connected to each other by a weld. Several bores 7 formed in the nozzle body 4 serve to convey the fuel from the pressure chamber 3 into the nozzle body 4.

[0016] A piston-shaped valve element 10 is arranged in the injector body 2 and the nozzle body 4. This valve element has a valve disc 110 at its combustion chamber-side end. The valve element 10 interacts with the valve disc 110 and a valve sealing seat 15 formed at the combustion chamber-side end of the nozzle body 4 to open and close an injection port. This port is opened by longitudinal movement of the valve element 10 between the valve disc 110 and the valve sealing seat 15. The nozzle body 4 is surrounded by a spray-shaping sleeve 5, which extends beyond the combustion chamber-side end of the nozzle body 4. The spray-shaping sleeve 5 serves to shape the fuel exiting the nozzle body 4, which can be liquid or gaseous, and to introduce it into the combustion chamber in a targeted manner and with optimal distribution. For this purpose, the spray-shaping sleeve 5 has an outlet opening 12 through which the fuel enters the combustion chamber.

[0017] A pre-tensioned closing spring 14 is arranged in the injector body 2. This spring is supported against a shoulder in the nozzle body 4 and exerts a closing force on the valve element 10, pressing the valve disc 110 against the valve seat 15. At its end facing away from the combustion chamber, the valve element 10 interacts with a push pin 11 to transmit an opening force. This force can be exerted on the push pin 11, and thus on the valve element 10, by an actuator (not shown in the drawing), such as an electromagnet. To shield the push pin 11 from the pressure chamber 3 and the fuel contained therein, the push pin 11 is surrounded by a bellows 13. The space formed inside the bellows 13 can be filled with a lubricant.

[0018] The receptacle 8, in the form of a water sleeve, has a conical contact surface 23. A sealing ring 20 is arranged between this contact surface 23 and the injector body 2 or the nozzle body 4, the sealing ring bearing against the contact surface 23 with a similarly conical sealing surface 22. Fig. Figure 2 shows an enlarged cross-section through this sealing ring 20. The sealing ring 20 has an inner projection 24 and an outer projection 25 on its conical sealing surface 22, which are formed as a bead-like circumferential ridge on the conical sealing surface 22 and are parallel to each other. The conical contact surface 23 and the conical sealing surface 22 each have an opening angle α that is identical and preferably in the range of 60° to 150°. This ensures that the sealing ring 20 rests uniformly on the contact surface 23 with the inner projection 24 and the outer projection 25.

[0019] The sealing ring 20 has a central opening 21 through which the fuel injector 1 is guided. The diameter D Di the inner elevation 24 and the diameter D i The central opening 21 has a ratio of preferably 1.05 to 1.2. The ratio of the diameter D Da the outer elevation 25 to the inner diameter D i The coefficient of friction is preferably 1.3 to 1.4, resulting in optimal force distribution between the sealing ring 20 and the contact surface 23. The width b of the sealing ring and its height h have a ratio of preferably b / h = 0.8 ... 1.2 to ensure the necessary stability.

[0020] The sealing ring 20 has a stepped pressure surface formed in the form of a first, inner pressure surface 27, which is formed on an inner shoulder of the sealing ring 20, and a second, outer pressure surface 28, which forms the end of the sealing ring 20 facing away from the combustion chamber. Fig. Figure 3a shows the position of the sealing ring 20 on the fuel injector 1 before assembly. A step 29 is formed on the outside of the spray-shaping sleeve 5, creating a clamping section 30 with a diameter slightly larger than the inner diameter D. i of the sealing ring 20. The sealing ring 20 is pushed over this clamping section 30, as shown in the Fig. 3a is indicated by the arrow, so that the sealing ring 20 is positively connected to the jet-shaping sleeve 5 and the fuel injector 1. The outer, second pressure surface 28 comes into contact with the shoulder 17 of the nozzle body 4. At the inner transition of the shoulder 17 to the cylindrical part of the nozzle body 4, an undercut 32 is formed in the form of a groove. The final position of the sealing ring 20 on the fuel injector 1 is shown in Fig. 3b shown.

[0021] The fuel injector 1 is now inserted into the receptacle 8 and brought into contact with the conical contact surface 23, so that the sealing ring 20 is clamped between the fuel injector 1 and the contact surface 23, as shown in Fig. 3b shown.

[0022] Subsequently, an axial clamping force is applied to the fuel injector 1, for example by a clamping jaw, which presses the sealing ring 20 both axially and radially inwards onto the fuel injector 1. In this process, the inner projection 24 and the outer projection 25 are preferably plastically deformed, creating a secure and gas-tight connection between the sealing ring 20 and the contact surface 23. The radial inward force then plastically deforms the sealing ring 20 at the inner edge of the outer pressure surface 28 to such an extent that it engages the undercut 32 in a form-fitting manner. This ensures that it remains on the fuel injector 1 even when the radial pressure, initially ensured by the frictional engagement on the clamping section 30, is relaxed due to plastic deformation, axial load, temperature effects, pressure surges from the combustion chamber, and similar influences. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 202 728 A1

[0002]

Claims

[1] Sealing ring (20) for arranging a fuel injector (1) in a receptacle (8) of an internal combustion engine, wherein the sealing ring (20) has a central opening (21) for passing through the fuel injector (1) and an at least substantially conical sealing surface (22) which, in the installed position in the internal combustion engine, faces the combustion chamber and comes into contact with a conical contact surface (23) in the receptacle (8) of the internal combustion engine, characterized by , that the sealing surface (22) has an inner circumferential protrusion (24) and an outer circumferential protrusion (25) with which the sealing ring (20) comes into contact with the contact surface (23). [2] Sealing ring (20) according to claim 1, characterized by , that the sealing ring (20) has a pressure surface (27, 28) on which the fuel injector (1) comes into installation position. [3] Sealing ring (20) according to claim 1 or 2, characterized by, that the protrusions on the sealing ring (20) are at least partially plastically deformable by axially clamping the fuel injector (1) in the receptacle (8). [4] Sealing ring (20) according to claim 3, characterized by , that the gap between the sealing ring (20) and the contact surface (23) is sealed gas-tight by the plastic deformation of the protrusions (24; 25). [5] Sealing ring (20) according to one of claims 1 to 4, characterized by , that the conical sealing surface (22) of the sealing ring (20) has an opening angle (α) of 60° to 150°. [6] Sealing ring (20) according to one of claims 1 to 5, characterized by , that the inner circumferential elevation (24) has a diameter (D Di ) exhibits a diameter that is 1.05 to 1.2 times the inner diameter (D i ) of the central opening (21). [7] Sealing ring (20) according to one of claims 1 to 6, characterized by, that the outer circumferential protrusion (25) has a diameter (DDa) which is 1.3 to 1.4 times the inner diameter (Di) of the central opening (21). [8] Method for mounting a fuel injector (1) in an internal combustion engine, wherein the internal combustion engine has a receptacle (8) for mounting the fuel injector (1), and with a conical contact surface (23) formed in the receptacle (8) against which the fuel injector (1) can be axially clamped, characterized by - Sliding a sealing ring (20) according to one of claims 1 to 7 onto the fuel injector (1), - Inserting the fuel injector (1) into the receptacle (8) so that the sealing ring (20) is positioned between a shoulder (17) of the fuel injector (1) and the conical contact surface (23), - Applying an axial clamping force to the fuel injector (1) in the receptacle (8) so that the sealing ring (20) is pressed by the fuel injector (1) with the two protrusions (24; 25) against the conical contact surface (23). [9] Method according to claim 8, characterized by , that when the sealing ring (20) is pushed on, a force-fit connection is formed with the fuel injector (1). [10] Method according to claim 8 or 9, characterized by , that the clamping force on the fuel injector (1) is so large that the two protrusions (24; 25) are at least partially plastically deformed.

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