Nozzle assembly for a fuel injection valve for injecting a gaseous and / or liquid fuel, fuel injection valve

Description

[0001] The invention relates to a nozzle assembly for a fuel injection valve with the features of the preamble of claim 1. Furthermore, the invention relates to a fuel injection valve for injecting a gaseous and / or liquid fuel into a combustion chamber of an internal combustion engine with such a nozzle assembly. State of the art

[0002] Fuel valves of the type described above are used, for example, in dual-fuel injection systems to supply fuel to an internal combustion engine. In a dual-fuel combustion process, a self-igniting liquid fuel, such as diesel fuel, is first introduced directly into the combustion chamber for preconditioning to provide the ignition temperature of the subsequently introduced main fuel, such as methane or liquid methanol. The main fuel can also be supplied to the combustion chamber directly or indirectly via the intake manifold. The metering of the main fuel is generally achieved using a fuel injection valve, which has at least one hydraulically actuated actuator in the form of a reciprocating nozzle needle. The liquid fuel used for preconditioning also serves as the control medium.A gas valve for a gaseous medium is known from DE 10 2009 002 836 A1.

[0003] The following four injector or nozzle concepts can be used in a two-component injection process: 1. Coaxial nozzle concept, which is implemented in one injector, 2. Parallel nozzle concept, which is implemented in one injector, 3. (Direct) two-injector concept, in which both injectors are located on the combustion chamber, and 4. (Indirect) two-injector concept, in which the injector for the main fuel is located on the intake manifold.

[0004] In the coaxial nozzle design, the high-pressure chambers of the two fuels are structurally connected via an annular gap, as this is necessary to guide the reciprocating nozzle needle. To prevent the main fuel from entering the area of ​​the liquid fuel (which serves as ignition fuel and / or control medium) via this guide, the pressure of the liquid fuel is regulated so that it is always higher than that of the main fuel. This ensures that only liquid fuel can enter the main fuel chamber via any leakage.

[0005] However, liquid fuel leakage into the main fuel system should be minimized and ideally avoided altogether. During deceleration phases of the internal combustion engine, a significant amount of liquid fuel can accumulate above the sealing seat of the injector needle, which controls the main fuel metering. This leads to excessive energy input into the combustion chamber during subsequent injections. This not only impairs driving comfort but also reduces the engine's reliability due to the resulting excessively high combustion chamber pressures. Furthermore, liquid fuel leakage into the main fuel system can prevent a gas-powered vehicle from obtaining the necessary certification.In order to obtain certification, it must be ensured that at least 90% of the energy used to operate the internal combustion engine is supplied by the main gaseous fuel.

[0006] Furthermore, if the internal combustion engine is to be temporarily operated solely on liquid fuel (e.g. "Diesel-Only operation"), this leads to the main fuel area being flooded with liquid fuel due to the high pressure differential.

[0007] When a gas-powered vehicle is switched off, the gas system should be kept under positive pressure, while the liquid fuel system is at ambient pressure. This means that gas can enter the liquid fuel system, which must be avoided for safety reasons.

[0008] Possible solutions to avoid the aforementioned disadvantages include minimizing the guide clearance and / or maximizing the guide length in the area where the nozzle needle is guided. Furthermore, the use of radial sealing elements, such as O-rings or piston rings, is known.

[0009] However, these approaches are insufficient due to wear in the guide area over the service life of the fuel injectors and / or due to insufficient functional reliability of the sealing elements. The present invention therefore aims to remedy this situation. In particular, it seeks to achieve reliable media separation in a fuel injector that can be designed as either a hydraulically actuated single-component or a hydraulically actuated dual-component injector.

[0010] To solve the problem, the nozzle assembly with the features of claim 1 is proposed. Advantageous embodiments of the invention are described in the dependent claims. Furthermore, a fuel injection valve with such a nozzle assembly is specified. Disclosure of the invention

[0011] The proposed nozzle assembly for a fuel injection valve for injecting a gaseous and / or liquid fuel into a combustion chamber of an internal combustion engine comprises a reciprocating closing element, interacting with a sealing seat, for opening and closing at least one injection port. The closing element is subjected on one side to combustion chamber pressure and on the other side to a control pressure prevailing in a control chamber, which is separated from a fuel supply path by a sleeve-shaped sealing element. According to the invention, the closing element is spherical or at least partially spherical in the region of a sealing surface interacting with the sealing seat and is directly or indirectly fluid-tight connected to the sleeve-shaped sealing element. To move the closing element, the control chamber is pressurized with a control medium.relieved, so that the closing element lifts off the sealing seat or is returned to the sealing seat depending on the control pressure in the control chamber.

[0012] The corrugated or bellows is particularly robust, which has a positive effect on the service life of the sealing element and thus on the service life of the fuel injector. Furthermore, it offers additional degrees of freedom that facilitate the compensation of any manufacturing and / or assembly-related tolerances. For example, lateral misalignments and / or tilting can be compensated for using such bellows elements. Manufacturing the axially and flexurally elastic corrugated or bellows from a metallic material further increases the robustness of the sealing element.

[0013] The spherical or at least partially spherical sealing element replaces a needle-shaped sealing element, in particular a nozzle needle. This also eliminates the leakage-prone guide for the nozzle needle, which does not preclude the spherical or partially spherical sealing element from being guided. The guidance is simply not provided by the sleeve-shaped sealing element, which in this case serves solely to seal the control chamber. Thus, the sleeve-shaped sealing element differs from a conventional sealing sleeve for receiving and guiding a nozzle needle, which, together with the nozzle needle, also defines the control chamber.

[0014] Because the spherical or semi-spherical closing element is directly or indirectly fluid-tightly connected to the sleeve-shaped sealing element, leakage from the control chamber into the fuel supply path and vice versa is reliably prevented. Therefore, the disadvantages mentioned in the introductory description do not occur.

[0015] Furthermore, the sealing performance in the area of ​​the sealing element's seat is increased because any coaxiality and / or angular deviations that may occur due to manufacturing and / or assembly tolerances can be better compensated for by the spherical or semi-spherical shape of the sealing element. This means that, unlike the nozzle needle, no or at least no significant lateral forces or tilting moments act on the spherical or semi-spherical sealing element, resulting in a uniform pressure distribution in the area of ​​the sealing element's seat. Consequently, wear in the area of ​​the sealing seat is reduced, ensuring a high level of sealing performance throughout the service life of the fuel injector.

[0016] According to a preferred embodiment of the invention, the spherical or semi-spherical closing element is not directly, but indirectly, connected to the sleeve-shaped sealing element in a fluid-tight manner via a sleeve. The sleeve allows for a simple change in diameter between the diameter of the sealing seat and the diameter of the control chamber. Since the opening behavior of the nozzle assembly or the fuel injection valve depends on these two parameters, the proposed sleeve simplifies the hydraulic adjustment. For this purpose, the sleeve is preferably stepped and / or designed as a flanged sleeve. In the flanged sleeve configuration, it also facilitates the fluid-tight connection of the sleeve-shaped sealing element to the sleeve.

[0017] The fluid-tight connection of the sleeve-shaped sealing element with the spherical or semi-spherical closing element or with the sleeve is preferably achieved by a material-bonded connection, in particular a soldered, welded, or adhesive bond. The soldered, welded, or adhesive bond is further preferably applied circumferentially within the area of ​​an annular sealing contact of the elements to be joined.

[0018] At its end furthest from the closing element, the sleeve-shaped sealing element is preferably bonded to a preferably plate-shaped body component of the nozzle assembly. The connection of the sleeve-shaped sealing element to the housing is thus also fluid-tight. The bond can again be achieved by means of a soldered, welded, or adhesive bond. The soldered, welded, or adhesive bond is preferably applied circumferentially so that leakage is reliably prevented. According to a preferred embodiment of the invention, the bond is achieved by means of laser welding, since this method is particularly precise.

[0019] Preferably, the plate-shaped body component forms a further boundary of the control chamber. Preferably, at least one throttle bore opening into the control chamber is formed in the preferably plate-shaped body component to create an inlet throttle and / or an outlet throttle. The inlet of a control medium into or outlet of a control medium from the control chamber can be adjusted by dimensioning the at least one throttle bore. Accordingly, the control pressure in the control chamber and thus the opening and closing behavior of the closing element can be influenced.

[0020] As a further development measure, it is proposed that a body be incorporated into the control chamber. This body reduces the volume of the control chamber, allowing it to be filled and emptied more quickly. This also allows for influencing the opening and closing behavior of the locking element. Preferably, the body is supported by and / or rigidly connected to the control component. In this case, the body can simultaneously serve as a stroke stop for the locking element.

[0021] Furthermore, preferably, the locking element is pre-tensioned towards the sealing seat by the sleeve-shaped sealing element. This eliminates the need for a separate closing spring. Since different pressures can exist on either side of the sleeve-shaped sealing element, a force acting in the closing direction is generated via the differential pressure, which in turn can be used to pre-tension the locking element.

[0022] Furthermore, it is proposed that the closing element has at least one surface grinding for guidance and / or is axially guided by guide ribs of a nozzle body of the nozzle assembly arranged at equal angular intervals. The at least one surface grinding or the guide ribs have exclusively a guiding function and no sealing function, since the same medium, namely the fuel to be injected, is present on both sides of the guide.

[0023] To solve the aforementioned problem, a fuel injection valve for injecting a gaseous and / or liquid fuel into a combustion chamber of an internal combustion engine with a nozzle assembly according to the invention is further proposed. The use of a nozzle assembly according to the invention ensures reliable media separation while maintaining a simple nozzle assembly design. This applies both to the two-component and single-component versions of the fuel injection valve. The single-component injection valve can be used to inject a liquid or a gaseous fuel. The injection is hydraulically controlled, so that in this case, the fuel and the hydraulic control medium must be separated. In addition to a liquid fuel, such as diesel fuel, other liquids can also serve as the hydraulic control medium.For example, hydraulic oil or water can be used as a control medium.

[0024] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 a schematic longitudinal section through a nozzle assembly according to the invention in a first preferred embodiment, Fig. 2 a schematic cross-section through the nozzle assembly of the Fig. 1 along the dash-dot line in the Fig. 1 , Fig. 3 a schematic longitudinal section through a nozzle assembly according to the invention in a second preferred embodiment and Fig. 4 a schematic longitudinal section through a nozzle assembly according to a third preferred embodiment. Detailed description of the drawings

[0025] The Fig. 1 Figure 1 shows a nozzle assembly 1 for a fuel injection valve for injecting fuel into a combustion chamber 2 of an internal combustion engine. The tip of the nozzle assembly protrudes into the combustion chamber 2. However, the arrangement on or at the combustion chamber 2 is not mandatory. For example, the fuel valve can also be arranged on an intake manifold (not shown) to inject the fuel indirectly into the combustion chamber 2 via the intake manifold.

[0026] The illustrated nozzle assembly 1 comprises a nozzle body 16, which forms a conical sealing seat 3 for a spherical closing element 4. The closing element 4 is movably mounted within the nozzle body 16 to open and close several injection ports 5. The spherical closing element 4 is guided by guide webs 15 of the nozzle body 16, which are arranged at equal angular intervals from one another (see Figure 1). Fig. 2 The spaces between the guide ribs 15 serve as a supply path 7 for the fuel, ensuring a fuel supply towards the injection openings 5. The closing element 4 forms a sealing surface 9, which, due to the spherical shape of the closing element 4, results in an annular sealing contact with the conical sealing seat 3. The annular sealing contact defines the seat diameter D1 (see Fig. 1 ).

[0027] The movements of the closing element 4 are hydraulically controlled. For this purpose, a control chamber 6 formed above the closing element 4 is pressurized or depressurized with a control medium, so that, depending on the control pressure in the control chamber 6, the closing element 4 lifts off the sealing seat 3 or is returned to the sealing seat 3. In the radial direction, the control chamber 6 is delimited by a sleeve-shaped sealing element 8, which is materially bonded and thus fluid-tight to the closing element 4 on one side and to a plate-shaped body component 11 on the other. In this way, a reliable separation of the control medium and the fuel is achieved. The materially bonded or fluid-tight connection is achieved in this case via a circumferential weld seam 17, in particular a laser weld seam. A throttle bore formed in the plate-shaped body component 11 provides access to the fuel.The control chamber 6 can be filled with the control medium via the inlet throttle 12 and relieved via a further throttle bore or outlet throttle 13. The fuel supply path 7 leads via an inlet channel 19 formed in the body component 11.

[0028] The sleeve-shaped sealing element 8 is designed as an axially and flexurally elastic bellows, preferably made of a metallic material. The inner diameter D2 of the sealing element 8 determines the diameter of the control chamber 6. The hydraulic adjustment, or the opening and closing behavior of the closing element 4, can be influenced by the diameter ratio of the two diameters D1 and D2.

[0029] In the case of an unfavorable diameter ratio, a diameter step can be achieved to optimize the diameter ratio using a sleeve 10. An example of such a sleeve 10 is shown in the Fig. 3 The sleeve 10 is designed as a collared sleeve, thus simplifying the material-bonded connection of the sleeve-shaped sealing element 8 to the sleeve. Here, too, the material bond is achieved by means of a weld seam 17. The same applies to the connection of the sleeve 10 to the spherical closing element 4.

[0030] To reduce the volume of the control chamber, a body 14 can be incorporated into the control chamber 6. An example of such a body 14 is shown in the Fig. 4 The illustrated body 14 is cylindrical and supported on the plate-shaped body component 11. At its other end, the body 14 forms a stroke stop 18 for the spherical locking element 4.

Claims

1. Nozzle assembly (1) for a fuel injection valve for injecting a gaseous and / or liquid fuel into a combustion chamber (2) of an internal combustion engine, comprising a reciprocally movable closing element (4) which interacts with a sealing seat (3) to release and close at least one injection opening (5), wherein the closing element (4) is spherical, or formed to be partially spherical at least in the region of a sealing surface (9) which interacts with the sealing seat (3), and is connected to a sleeve-shaped sealing element (8) directly or indirectly in a fluid-tight manner, and the sealing element (8) is designed as an axially and flexibly elastic corrugated or folding bellows made from a metallic material, characterized in that the closing element (4) is impinged, on the one hand, by combustion chamber pressure and, on the other hand, by a control pressure which prevails in a control chamber (6) which is separated from an inlet path (7) for the fuel by the sleeve-shaped sealing element (8), wherein the control chamber (6) for moving the closing element (4) is impinged or relieved by a control medium in such a way that the closing element (4) as a function of the control pressure in the control chamber (6) is lifted from the sealing seat (3) or returned into the sealing seat (3).

2. Nozzle assembly according to Claim 1, characterized in that the closing element (4) is connected indirectly to the sealing element (8) in a fluid-tight manner by way of a sleeve (10) which is preferably stepped and / or designed as a collar sleeve.

3. Nozzle assembly according to one of the preceding claims, characterized in that the sleeve-shaped sealing element (8) is connected to a preferably plate-shaped body component (11) of the nozzle assembly (1) in a materially integral manner, for example by means of laser welding.

4. Nozzle assembly according to Claim 3, characterized in that formed in the preferably plate-shaped body component (11) is at least one throttle bore (12, 13) leading into the control chamber (6) for forming an inlet throttle (12) and / or an outlet throttle (13).

5. Nozzle assembly according to one of the preceding claims, characterized in that received in the control chamber (6) is a body (14) which is preferably supported on the body component (11) and / or is fixedly connected to the body component (11).

6. Nozzle assembly according to one of the preceding claims, characterized in that the closing element (4) is preloaded in the direction of the sealing seat (3) by the sleeve-shaped sealing element (8).

7. Nozzle assembly according to one of the preceding claims, characterized in that the closing element (4) has at least one roughened surface for guiding and / or is guided axially by way of guide webs (15) of a nozzle body (16) of the nozzle assembly (1) that are disposed at an identical mutual angular spacing.

8. Fuel injection valve for injecting a gaseous and / or liquid fuel into a combustion chamber (2) of an internal combustion engine, having a nozzle assembly (1) according to one of the preceding claims.