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

Abstract

The invention relates to a nozzle assembly (1) of a fuel injection valve for injecting gaseous and / or liquid fuel into a combustion chamber (2) of an internal combustion engine, comprising a reciprocating closing element (4) which cooperates with a sealing seat (3), said closing element being used to release and close at least one injection opening (5), said closing element being loaded on one side by the combustion chamber pressure and on the other side by a control pressure which is present in a control chamber (6), said control chamber being separated from an inflow path (7) for the fuel by a sleeve-shaped sealing element (8). According to the invention, the closing element (4) is shaped spherically or at least partially spherically in the region of a sealing surface (9) which cooperates with the sealing seat (3) and is in fluid-tight connection with the sleeve-shaped sealing element (8) directly or indirectly. Furthermore, the invention relates to a fuel injection valve having such a nozzle assembly (1).

Description

Field of the Invention

[0001] The present invention relates to a nozzle assembly of a fuel injection valve. Furthermore, the present invention relates to a fuel injection valve for injecting gaseous fuel and / or liquid fuel into a combustion chamber of an internal combustion engine having such a nozzle assembly. Background Art

[0002] Fuel valves of the above type are used, for example, in dual fuel injection methods for supplying fuel to an internal combustion engine. In a dual fuel combustion method, first, a compression-ignited liquid fuel, such as diesel fuel, is directly introduced into the combustion chamber for preconditioning in order to provide an ignition temperature for a subsequently introduced main energy carrier, such as methane gas or liquid methanol. The main energy carrier or main fuel can likewise be supplied to the combustion chamber directly or indirectly via an intake pipe. Usually, the metering of the main fuel is effected by means of a fuel injection valve which has at least one hydraulically actuatable regulating mechanism in the form of a reciprocating nozzle needle. The liquid fuel used for preconditioning serves as a control medium in this case.

[0003] In a dual fuel injection method, the following four injector concepts or nozzle concepts can be used:

[0004] 1. A coaxial nozzle concept implemented in one injector,

[0005] 2. A parallel nozzle concept implemented in one injector,

[0006] 3. A (direct) dual injector concept, in which two injectors are arranged at the combustion chamber, and

[0007] 4. An (indirect) dual injector concept, in which the injector for the main fuel is arranged on the intake pipe.

[0008] In the coaxial nozzle concept, the high-pressure chambers of the two fuels are structurally connected to one another via an annular gap because the reciprocating nozzle needle has to be guided. In order to prevent, for safety reasons, the main fuel from being guided into the region of the liquid fuel used as ignition fuel and / or as control medium, the pressure of the liquid fuel is adjusted such that this pressure is always higher than the main fuel pressure. In this way, it is ensured that only liquid fuel reaches the main fuel region during a leakage stroke.

[0009] However, the leakage of liquid fuel into the main fuel area should be minimized and ideally completely avoided. Because during the propulsion phase of an internal combustion engine, a small amount of liquid fuel can accumulate by controlling the sealing seat of the nozzle needle for the main fuel metering. These fuel amounts result in an excessive energy input into the combustion chamber during the subsequent injection. This not only impairs driving comfort but also the stability of the internal combustion engine due to the excessive combustion chamber pressure generated thereby. In addition, the consequence of liquid fuel leakage into the main fuel area may be that a vehicle with a gas drive cannot obtain the necessary certification. Because to obtain this certification, it must be ensured that at least 90% of the energy used for the operation of the internal combustion engine is applied by the gaseous main fuel.

[0010] Furthermore, if the internal combustion engine can only be operated temporarily with liquid fuel (e.g., "diesel only operation"), this results in the main fuel area being filled with liquid fuel due to a relatively high pressure drop.

[0011] If a vehicle with a gas drive is parked, an overpressure is maintained in the gas system, while only the ambient pressure exists in the liquid fuel area. Thus, gas can reach the liquid fuel area, which should be avoided for safety-technical reasons.

[0012] Solutions for avoiding the above-mentioned disadvantages are provided, for example, by minimizing the guiding clearance and / or maximizing the guiding length in the guiding area of the nozzle needle. In addition, it is known to use radial sealing elements such as O-rings or piston rings.

[0013] However, these solutions are insufficient due to wear in the guiding area during the service life of the fuel injection valve and / or due to the lack of functional reliability of the sealing elements. Therefore, the object of the present invention is to achieve compensation here. In particular, a reliable separation of media should be achieved in the fuel injection valve, which can be designed not only as a hydraulically actuated single-fuel injection valve but also as a hydraulically actuated dual-fuel injection valve. Summary of the Invention

[0014] To solve this task, a nozzle assembly is proposed according to the present invention. Advantageous expansions of the present invention can be derived from the preferred embodiments. In addition, a fuel injection valve having such a nozzle assembly is also proposed.

[0015] A nozzle assembly proposed for a fuel injection valve for injecting gaseous and / or liquid fuel into a combustion chamber of an internal combustion engine includes a reciprocating closing element that cooperates with a sealing seat and is used to release and close at least one injection opening. The closing element is loaded on one side by the combustion chamber pressure and on the other side by a control pressure that exists in a control chamber, which is separated from the inflow path for the fuel by a sleeve-shaped sealing element. According to the invention, the closing element is shaped spherically or at least partially spherically in the region of the sealing surface that cooperates with the sealing seat and is fluid-sealedly connected to the sleeve-shaped sealing element directly or indirectly.

[0016] The spherical or at least partially spherical closing element replaces the needle-shaped closing element, in particular the nozzle needle. Thereby, the nozzle needle guide with leakage is also eliminated, which does not exclude that the spherical or partially spherical closing element is guided. The guiding is only not achieved by the sleeve-shaped sealing element, which is only used for sealing the control chamber here. Therefore, the sleeve-shaped sealing element differs from the conventional sealing sleeve for receiving and guiding the nozzle needle in that the conventional sealing sleeve delimits the control chamber together with the nozzle needle at the same time.

[0017] By the fluid-sealed connection of the spherical or partially spherical closing element to the sleeve-shaped sealing element directly or indirectly, leakage from the control chamber to the fuel inflow path and in the opposite direction is reliably prevented. Therefore, the disadvantages mentioned at the beginning of the specification do not occur either.

[0018] In addition, the sealing performance in the region of the sealing seat of the closing element is improved because possible coaxiality deviations and / or angular deviations caused by manufacturing and / or assembly tolerances can be better compensated by the spherical or partially spherical shape of the closing element. This means that, different from the nozzle needle, no or at least no notable lateral force or tilting moment acts on the spherical or partially spherical closing element, which results in a uniform pressure distribution in the region of the sealing seat of the closing element. Accordingly, the wear in the region of the sealing seat is reduced, ensuring a higher sealing seat tightness during the service life of the fuel injection valve.

[0019] According to a preferred embodiment of the invention, the spherical or partially spherical closing element is not fluid-sealedly connected to the sleeve-shaped sealing element directly, but indirectly through a sleeve. The diameter jump between the sealing seat diameter and the control chamber diameter can be achieved in a simple manner through the sleeve. Since the opening behavior of the nozzle assembly or the fuel injection valve is related to these two parameters, the proposed sleeve can be used to simplify the hydraulic coordination. For this purpose, the sleeve is preferably stepped and / or implemented as a flange sleeve. In addition, in the configuration as a flange sleeve, the flange sleeve facilitates the fluid-sealed connection between the sleeve-shaped sealing element and the sleeve.

[0020] The fluid-tight connection of the sleeve-shaped sealing element to the spherical or partially spherical closing element and / or to the sleeve is preferably achieved by a material-locking connection, in particular a soldered connection, a welded connection or an adhesive connection. Furthermore, the soldered joint, the welded joint or the adhesive joint is preferably arranged circumferentially in the region of the annular sealing contact of the elements to be connected.

[0021] Furthermore, it is proposed that the sleeve-shaped sealing element is axially elastic. In this way, it is ensured that the sleeve-shaped sealing element can receive the movement of the reciprocating closing element. Preferably, the sleeve-shaped sealing element is a wave tube or a bellows that is axially elastic and flexurally elastic. Such a tube element (Balgelement) has proven to be particularly robust, which has a positive effect on the service life of the sealing element and thus on the service life of the fuel injection valve. In addition, such a tube element has additional degrees of freedom, which facilitate the compensation of possible tolerances determined by manufacturing and / or assembly. For example, lateral misalignment and / or inclination can be compensated for by means of such a tube element. Furthermore, it is preferred that the axially elastic and flexurally elastic wave tube or bellows is made of a metallic material. In this way, the robustness of the sealing element can be further increased.

[0022] Preferably, the sleeve-shaped sealing element is connected in a material-locking manner to the preferably plate-shaped body member of the nozzle assembly at its end facing away from the closing element. Thus, the housing-side connection of the sleeve-shaped sealing element is also carried out in a fluid-tight manner. The material-locking can again be caused by a soldered connection, a welded connection or an adhesive connection. The soldered joint, the welded joint or the adhesive joint is preferably arranged circumferentially so that leakage is reliably prevented. According to a preferred embodiment of the invention, the material-locking is achieved by means of laser welding, since this method is particularly precise.

[0023] Preferably, the plate-shaped body member is the other boundary of the control chamber. Preferably, at least one throttle hole leading into the control chamber is configured in the preferably plate-shaped body member for forming an inflow throttle and / or an outflow throttle. By dimensioning the at least one throttle hole, the inflow rate of the control medium into the control chamber or the outflow rate of the control medium from the control chamber can be set. Accordingly, the control pressure in the control chamber and thus the opening and closing behavior of the closing element can be influenced.

[0024] As a measure for expansion, it is proposed to receive a body in the control chamber. This body reduces the control chamber volume so that the control chamber can be filled or emptied more quickly. In this way, the opening and closing behavior of the closing element can also be influenced. Preferably, the body is supported on the body member and / or fixedly connected to the body member. In this case, the body can simultaneously serve as a lifting stop for the closing element.

[0025] Furthermore, it is preferred that the closing element is preloaded by the sleeve-shaped sealing element in the direction of the sealing seat. This can eliminate the need for a separate closing spring. Since there may be different pressures on both sides of the sleeve-shaped sealing element, a force acting in the closing direction is generated by the pressure difference, and this force can in turn be used to preload the closing element.

[0026] Furthermore, it is proposed that the closing element has at least one planar grinding portion for guiding and / or is axially guided by guide tabs arranged at the same angular spacing relative to each other by the nozzle bodies of the nozzle assembly. At least one planar grinding portion or guide tab only has a guiding function and no sealing function, because the same medium, more precisely the fuel to be injected, exists on both sides of the guiding portion.

[0027] To solve the task mentioned at the beginning, a fuel injection valve for injecting gaseous fuel and / or liquid fuel into the combustion chamber of an internal combustion engine having a nozzle assembly according to the invention is also proposed. The application of the nozzle assembly according to the invention ensures reliable separation of the media while the structure of the nozzle assembly is simple. This applies not only to the embodiment of the fuel injection valve as a dual fuel injection valve, but also to the embodiment of the fuel injection valve as a single fuel injection valve. The single fuel injection valve can be used to inject liquid or gaseous fuel. Here, the injection is hydraulically controlled, so that in this case the two media of fuel and hydraulic control medium must be separated. In addition to liquid fuel, such as diesel fuel, other fuels can also be used as the hydraulic control medium. For example, hydraulic oil or water can be used as the control medium. Description of the Drawings

[0028] The preferred embodiments of the present invention will be described in detail below with reference to the drawings. The drawings show:

[0029] Figure 1 A schematic longitudinal section of a nozzle assembly according to the invention according to a first preferred embodiment,

[0030] Figure 2 Figure 1 of the nozzle assembly along Figure 1 a schematic cross-section of the dotted line in

[0031] Figure 3 A schematic longitudinal section of a nozzle assembly according to the invention according to a second preferred embodiment and,

[0032] Figure 4 A schematic longitudinal section of a nozzle assembly according to the invention according to a third preferred embodiment. Detailed Description of the Embodiments

[0033] Figure 1The nozzle assembly 1 of a fuel injection valve for injecting fuel into the combustion chamber 2 of an internal combustion engine is shown. The tip of the nozzle assembly projects into the combustion chamber 2. However, it is not necessarily mandatory to be arranged on the combustion chamber 2. For example, the fuel valve can also be arranged on an intake pipe (not shown) in order to inject fuel indirectly into the combustion chamber 2 through the intake pipe.

[0034] The shown nozzle assembly 1 includes a nozzle body 16, which forms a conical sealing seat 3 for a spherical closing element 4, which is received in the nozzle body 16 in a reciprocating manner for releasing and closing a plurality of injection openings 5. Here, the spherical closing element 4 is guided by guide tabs 15 of the nozzle body 16, which are arranged at the same angular spacing relative to each other (see Figure 2 ). The intermediate space between the guide tabs 15 serves as an inflow path 7 for the fuel, such that the inflow of the fuel in the direction of the injection openings 5 is ensured. The closing element 4 forms a sealing surface 9, which causes an annular sealing contact with the conical sealing seat 3 due to the spherical shape of the closing element 4. The annular sealing contact defines a seat diameter D1 (see Figure 1 ).

[0035] The movement of the closing element 4 is hydraulically controlled. For this purpose, a control chamber 6 constructed above the closing element 4 is loaded or unloaded with a control medium, such that the closing element 4 is lifted from the sealing seat 3 or reset into the sealing seat 3 according to the control pressure in the control chamber 6. In the radial direction, the control chamber 6 is bounded by a sleeve-shaped sealing element 8, which is connected in a material-locking and thus fluid-tight manner on one side to the closing element 4 and on the other side to a plate-shaped body member 11. In this way, a reliable separation of the control medium from the fuel is caused. Here, the material-locking and fluid-tight connection is achieved by a surrounding fusion weld 17, in particular a laser weld. The control chamber 6 can be filled with the control medium through a throttle hole or an inflow throttle 12 constructed in the plate-shaped body member 11, and the control chamber can be unloaded through another throttle hole or an outflow throttle 13. The inflow path 7 of the fuel passes through an inflow channel 19 constructed in the body member 11.

[0036] Here, the sleeve-shaped sealing element 8 is implemented as an axially elastic and flexurally elastic bellows, which is 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 coordination 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.

[0037] In the case of an unfavorable diameter ratio, a diameter jump can be achieved by means of a sleeve 10 for optimizing the diameter ratio. Such a sleeve 10 is exemplary shown in Figure 3It is shown in. The sleeve 10 is embodied as a flange sleeve, such that the material-locking connection between the sleeve-shaped sealing element 8 and the sleeve is simplified. Herein, this material-locking is also produced by means of a weld seam 17. The same applies to the connection between the sleeve 10 and the spherical closing element 4.

[0038] In order to reduce the control chamber volume, a body 14 can be received in the control chamber 6. Such a body 14 is exemplarily shown in Figure 4 It is shown in. The shown body 14 is cylindrical and supported on a plate-shaped body member 11. At the other end, the body 14 forms a lifting stop 18 for the spherical closing element 14.

Claims

1. A nozzle assembly (1) of a fuel injection valve for injecting gaseous fuel and / or liquid fuel into a combustion chamber (2) of an internal combustion engine, comprising a reciprocating closing element (4) which cooperates with a sealing seat (3), the closing element being for releasing and closing at least one injection opening (5), wherein, The closing element (4) is shaped spherically or at least partially spherically in the region of the sealing surface (9) which acts together with the sealing seat (3) and is connected fluid-tightly directly or indirectly to the sleeve-shaped sealing element (8), and the sleeve-shaped sealing element (8) is configured as an axially elastic and flexurally elastic corrugated tube or bellows made of a metallic material, wherein the closing element (4) is loaded on one side by the combustion chamber pressure and on the other side by a control pressure which prevails in the control chamber (6), which is separated from the inflow path (7) for the fuel by the sleeve-shaped sealing element (8), wherein the control chamber (6) is loaded with or unloaded of a control medium for moving the closing element (4) such that the closing element (4) is lifted from the sealing seat (3) or reset into the sealing seat (3) depending on the control pressure in the control chamber (6).

2. The nozzle assembly according to claim 1, characterized in that, The closing element (4) is connected fluid-tightly to the sealing element (8) indirectly via a sleeve (10).

3. The nozzle assembly according to claim 2, wherein, The sleeve-shaped sealing element (8) is connected in a force-fitting manner to the body member (11) of the nozzle assembly (1).

4. The nozzle assembly according to claim 3, characterized in that, At least one throttle hole (12, 13) leading into the control chamber (6) is configured in the body member (11) to form an inflow throttle section (12) and / or an outflow throttle section (13).

5. The nozzle assembly according to claim 3 or 4, characterized in that, A body (14) is received in the control chamber (6), which body is supported on the body member (11) and / or is fixedly connected to the body member (11).

6. The nozzle assembly according to any one of claims 1 to 4, characterized in that, The closing element (4) is pre-tensioned in the direction of the sealing seat (3) by the sleeve-shaped sealing element (8).

7. The nozzle assembly according to any one of claims 1 to 4, characterized in that, The closing element (4) has at least one planar ground portion for guiding and / or is axially guided by guide tabs (15) arranged at the same angular spacing relative to one another by the nozzle body (16) of the nozzle assembly (1).

8. The nozzle assembly according to claim 2, wherein, The sleeve is implemented in a stepped manner and / or as a flange sleeve.

9. The nozzle assembly according to claim 3, characterized in that, The force-fitting connection is effected by laser welding.

10. The nozzle assembly according to claim 3 or 4 or 9, characterized in that, The body member (11) is configured in a plate-like manner.

11. A fuel injection valve for injecting gaseous fuel and / or liquid fuel into a combustion chamber (2) of an internal combustion engine having a nozzle assembly (1) according to one of claims 1 to 10.

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