Injector for injecting a gaseous medium

Abstract

The present invention relates to an injector (1) for injecting a gaseous medium, in particular a gaseous fuel, preferably hydrogen, into a combustion chamber (20) of an internal combustion engine. The injector (1) comprises, among other things, an axially movable valve closing element (5) for opening and closing at least one opening on a sealing seat (7), an actuator (21) for actuating the valve closing element (5), and a flow-influencing geometry (10) arranged downstream of the sealing seat (7) in terms of flow technology. According to the invention, the flow-influencing geometry (10) is designed such that, downstream of the sealing seat (7), it forms an inner contour (9) segmented over the circumference, in which at least one structural element (22) is provided, which, running in the downstream direction over its axial length (l), enables a radially inward flow deflection up to an outlet (19).

Description

State of the art

[0001] The present invention relates to an injector for injecting a gaseous medium, in particular a gaseous fuel, into a combustion chamber of an internal combustion engine. Specifically, the invention relates to an injector with which hydrogen can be injected directly into the combustion chamber of a mixture-compressing, spark-ignition internal combustion engine.

[0002] Gas injectors are known from the state of the art in various designs. Due to cost advantages and improved environmental compatibility, gaseous fuels have recently become increasingly popular. Compared to injectors for liquid fuels, the injected gas volume occupies a much larger volume than an equivalent amount of liquid fuel. This results in an increased stroke requirement for a closing element, which is usually actuated by a magnetic actuator. Designing a magnetic circuit using standard materials is very difficult or sometimes impossible due to the limited installation space. Materials with higher magnetic force are very expensive and sometimes harmful to health (e.g., FeCo).

[0003] DE 10 2021 206 438 A1 already discloses a gas nozzle for a gas valve, which comprises a nozzle body that is at least partially hollow-cylindrical in shape and forms a sealing seat over which a gas flow path leads. Furthermore, the gas valve has a valve-closing element that is partially accommodated in the nozzle body and has an end section that is arranged outside the nozzle body and has a sealing contour that interacts with the sealing seat. Furthermore, the gas valve has a sleeve that surrounds the nozzle body and the end section of the valve-closing element and delimits the gas flow path downstream of the sealing seat. The gas flow path downstream of the sealing seat has a cross-sectional constriction to achieve the Venturi effect, in the region of which at least one intake channel opens. The sleeve is designed in the form of a blow cap that can be applied to the nozzle body.

[0004] Another injector for injecting a gaseous medium is also known from WO 2023 / 001384 A1. The blow cap, which can be placed on a nozzle body, has a sleeve-shaped base body with a circumferential surface that merges into a base region at the downstream end. The base region is designed such that at least one obliquely or asymmetrically discharging outlet opening is provided. Furthermore, a flow guide section directed inward toward the valve closing element, counter to the flow direction, is formed in the base region, which deflects the gas to be discharged. Disclosure of the invention

[0005] The injector according to the invention for injecting a gaseous medium, in particular a gaseous fuel, into a combustion chamber of an internal combustion engine, with the features of claim 1 has the advantage that an optimized gas flow in the injector is made possible by the geometric design of a flow-influencing geometry arranged downstream of the sealing seat, so that the internal flow of the gaseous medium is designed to be as loss-free as possible via the inner contour of the cap-shaped attachment body, so that the back pressure below, i.e. downstream of the valve closing element, is reduced and at the same time the jet can be introduced into the combustion chamber in a targeted manner.

[0006] In addition, the forces acting on the valve closing element are reduced to a minimum in a special way. This reduces the magnetic force of an actuator that must be selected to keep the injector open, thus enabling the use of cost-effective materials in the actuator's magnetic circuit.

[0007] This is achieved according to the invention in that the injector has a valve closing element for opening and closing at least one opening on a sealing seat. The valve closing element is preferably an axially movable valve needle with a plate-shaped end section. Furthermore, an actuator is provided for actuating the valve closing element. The actuator is preferably a magnetic actuator, but can also be, for example, a mechanically or (piezo-) electrically operated actuator. Further preferably, the actuator is configured to actively open the valve closing element by means of a lifting movement and to keep it open, while the valve closing element is closed by a spring force.

[0008] The flow-influencing geometry, which is housed in particular in a cap-shaped attachment body, a blow cap for short, is characterized according to the invention in that it results downstream of the sealing seat as a circumferentially segmented inner contour in which at least one structural element is provided that, extending in the downstream direction over its axial length, enables a radially inward flow deflection up to an outlet. In this way, mixture formation is particularly improved.

[0009] The subclaims describe preferred developments of the invention.

[0010] The flow control geometry according to the invention is integrated into a very open attachment structure without base areas, following the sealing seat. Such open attachment bodies offer the advantages of a very simple design and easy, highly reproducible production. Furthermore, there is no blocked dead volume inside the attachment body, which could disadvantageously lead to premature pre-ignition.

[0011] The inventive concept allows for particularly high flexibility in the design of the spray pattern. The gas flow can be distributed very evenly throughout the entire combustion chamber, which improves mixture formation and increases efficiency.

[0012] It is particularly advantageous to create the flow influencing geometry tapering in the direction of flow by means of conical or convex or concave curved structural elements.

[0013] The highly variable design of the inner contour by means of structural elements according to the invention in turn enables a very flexible use of sleeves or attachment bodies on injectors in various combustion chamber geometries of internal combustion engines.

[0014] The present invention is preferably used in injection systems that inject hydrogen directly into a combustion chamber. In particular, the injector is suitable for directly injecting hydrogen into a combustion chamber of an internal combustion engine. drawing

[0015] Preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings. Fig. 1 is a schematic sectional view of an injector for injecting a gaseous medium according to the prior art, Fig. 2 a sectional view of a known cap-shaped attachment body for an injector according to Fig. 1, Fig. 3 a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a first embodiment, Fig. 4 a sectional view through the attachment body along a section line IV-IV in Fig. 3, Fig. 5 a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a second embodiment and Fig. 6 a sectional view through the attachment body along a section line VI-VI in Fig. 5. Preferred embodiments of the invention

[0016] For a better understanding of the invention, the following is based on the Fig. 1 and Fig. 2 describes the basic structure of an injector for injecting a gaseous medium as well as a known structure of a flow influencing geometry arranged downstream of the valve seat.

[0017] In the Fig. Figure 1 shows a schematic cross-sectional view of the known injector 1 for injecting a gaseous medium. Since the invention is directed to the flow-influencing geometry 10, which is arranged downstream of the valve seat 3 in terms of flow technology, only this assembly will be described in more detail here for the known injector 1. For example, a magnetic actuator 21 is provided to actuate the injector 1, so that the injector 1 can be controlled in a targeted manner.

[0018] The injector 1 also has a nozzle body 2, which on the injection side forms a conically shaped valve seat 3 at its end for a valve closing element 5 that opens outwards, i.e., opens towards a combustion chamber 20. The valve closing element 5 is guided axially movably within the nozzle body 2 via a guide 18. In addition, the valve closing element 5 has an end section 6 in the form of a valve disk, which forms a sealing seat 7 corresponding to the valve seat 3. The two sealing seat partners, valve seat 3 and valve closing element 5, are each made of metal. The geometric and material design is such that sufficient tightness is guaranteed during operation of a hydrogen engine.In the event of a fault, a shut-off system (not shown here) installed upstream of the injector 1 for safety reasons would interrupt the supply of the gaseous medium, particularly the highly volatile hydrogen. The sealing contour of the end section 6 of the valve closing element 5 is, for example, rounded, while the valve seat 3 on the nozzle body 2 has a conical shape. However, other contours are also conceivable.

[0019] The nozzle body 2 and the end section 6 of the valve closing element 5 are surrounded by a sleeve 8 for jet shaping. In the following, in particular also with reference to the invention, reference is generally made to a flow-influencing geometry 10 arranged downstream of the sealing seat 7. This can either be formed directly as a single piece on the nozzle body 2, which, however, requires a high manufacturing outlay, or it can be integrated into an additional component, wherein this component, with reference to the embodiments according to the prior art, is Fig. 1 and Fig. 2 is generally referred to as a sleeve 8. The sleeve 8 has a large overlap length with the nozzle body 2 in order to be able to securely and reliably fasten the sleeve 8. In principle, however, it can also be referred to as a cap-shaped attachment body 8, which, with reference to the exemplary embodiments according to the invention, is also defined as a blow cap 8.

[0020] The sleeve 8 and the end portion 6 of the valve closure element 5 jointly define a gas flow path 4, into which at least one intake channel 15 formed in the sleeve 8 opens. Air from the environment can be sucked into the gas flow path 4 via the one or more intake channels 15.

[0021] If the valve closing element 5 is in an open position lifted from the valve seat 3, the gas flow path 4 then leads via the valve seat 3 into an interior of the sleeve 8, which is characterized by a special shape with an inner contour 9. Starting from a cylindrical section 11 of the sleeve 8 and following the valve closing element 5 in the flow direction, a cross-sectional reduction occurs at a large axial distance from the valve closing element 5 in a central cylindrical axial region 13 of the flow-influencing geometry 10 of the sleeve 8, with the taper being achieved via a conically extending section 12 in the inner contour 9 of the sleeve 8. The intake channels 15 open into the inner contour 9 of the sleeve 8 precisely in the central axial region 13.

[0022] The reduction in cross-section within the gas flow path 4 ensures that, as the gas flows out through the gas flow path 4 toward an outlet 19, air is drawn from the environment into the gas flow path 4 via the intake channels 15 ("Venturi effect"). This means that air is mixed with the gas before it reaches the outlet 19, thus improving the mixture preparation.

[0023] The cross-sectional reduction is offset by the fact that the central axial region 13 is again followed by a conically extending section 14, but in this case widening conically in the direction of flow, with this section 14 extending to the outlet 19. The cross-sectional reduction in the inner contour 9 of the sleeve 8 is intended to achieve the Venturi effect, which is optimized together with the air admixture. Experience has shown that such a solution or other known geometries or inner contours of cap-shaped attachment bodies do not achieve sufficiently good results with regard to the introduction of the jets into the combustion chamber 20 or their jet guidance and jet shaping for optimal combustion.

[0024] Therefore, the object of the invention is to provide an inner contour 9 of a cap-shaped attachment body 8 with a flow-influencing geometry 10 arranged downstream of the sealing seat 7, with which optimal combustion results are achieved due to the flow guidance according to the invention.

[0025] Injection systems for the direct injection of a gaseous medium, in particular hydrogen, but also CNG, methane, ammonia, or mixtures of the aforementioned gases, have the task of specifically controlling the dosage and injection direction of the gas jet(s) into the combustion chamber 20 via injection valves or, more generally, injectors 1. For this purpose, appropriate sleeves or blow caps 8 can be used on the injector 1, as already explained above. Furthermore, injection systems for direct (hydrogen) injection require a large lift of the valve needle with the valve closing element 5. The magnetic circuit design (magnetic actuator 21) with the known standard materials is very difficult or sometimes impossible due to the limited installation space. Materials with higher magnetic force and thus better B / H characteristics are very expensive and sometimes even harmful to health (e.g., FeCo).In this respect, a reduction in magnetic force should also be achieved through improved beam guidance.

[0026] The core of the invention is to design the internal flow of the gaseous medium with as little loss as possible via the inventive inner contour 9 of the cap-shaped attachment body 8, so that the back pressure located below, i.e. downstream of the plate-shaped end section 6 of the valve closing element 5 is reduced and, at the same time, the jet can be introduced into the combustion chamber 20 in a targeted manner. This defined inner contour 9 is aimed in particular at improved mixture formation by deliberately deflecting the gas flow radially inward in a downstream direction. Due to the highly variable contouring of the inner contour 9, a very flexible use of sleeves or attachment bodies 8 on injectors 1 in various combustion chamber geometries of internal combustion engines is possible.

[0027] The following are based on the Fig. 3 to 6 injectors 1 with flow influencing geometries 10 according to the invention, arranged downstream of the valve seat 3 in terms of flow technology, according to preferred embodiments of the invention are described in detail. As already mentioned, these flow influencing geometries 10 can be formed directly as one piece on the nozzle body 2 or, as shown in all figures, can be integrated into an additional component, which can be referred to as a cap-shaped attachment body 8 (in short, blow cap 8). The attachment body 8 will usually have a significantly smaller overlap length with the nozzle body 2 than in Fig. 1. The only essential requirement is a secure and reliable attachment to the nozzle body 2, which enables perfect and axially parallel alignment to the injector 1. Conventional joining methods such as pressing, welding, soldering, gluing, or combinations thereof can be used.

[0028] In the Fig. Figure 3 shows a first embodiment of a flow-influencing geometry 10 arranged downstream of the valve seat 3 in a cap-shaped attachment body 8 and created via an inventive inner contour 9. The valve closing element 5 with its plate-shaped end section 6 is shown only schematically and in a simplified manner. However, the end section 6 can also have chamfers or rounded portions on its outer contour.

[0029] The flow-influencing geometry 10 created with the internal contour 9 according to the invention has an essential geometric specification, which primarily generates a radially inward deflection of the gas flow in the downstream direction. Overall, the attachment body 8 is designed as an open blow-off body, i.e., the thin-walled sleeve contour of the overlap area for attachment to the nozzle body 2 also largely continues in the downstream direction. Such open attachment bodies 8 have the advantages of a very simple design and simple, highly reproducible production. Furthermore, there is no blocked dead volume inside the attachment body 8, which could disadvantageously lead to premature pre-ignition.

[0030] The inner contour 9 of the attachment body 8 is characterized according to the invention by at least one structural element 22 extending over a circumferential region of the attachment body 8 and having an axial length l, which generates a gas flow deflection radially inward to the outlet 19 of the attachment body 8. Generally speaking, the flow-influencing geometry 10 downstream of the sealing seat 7 results as an inner contour 9 segmented over the circumference, in which at least one structural element 22 with a length l is provided.

[0031] Fig. 4 shows a sectional view through the attachment body 8 along a section line IV-IV in Fig. 3. It can be seen that in the illustrated embodiment, three structural elements 22 are provided, evenly distributed over the circumference. Here, the structural elements 22 are located at an angular distance of 120° from one another, with their respective circumferential extents being largely the same. Since the intermediate regions between the structural elements 22 are also largely of the same size, in this specific case, structural elements 22 result which extend over an angle of approximately 60°. The structural elements 22 are designed in such a way that, starting immediately downstream of the end section 6 of the valve closing element 5, they ensure a continuous increase in the wall thickness of the attachment body 8 up to the outlet 19, so that the gas flow is deflected radially inwards in individual circumferential regions of the attachment body 8.The structural elements 22 give the attachment body 8 a converging conicity with flow cross-sections tapering in the flow direction.

[0032] The attachment body 8 has at least one structural element 22, but ideally two to eight structural elements 22, which divert the gas flow obliquely into the center of the attachment body 8 and thus create a uniform gas jet.

[0033] While the structural elements 22 of the Fig. 3 and Fig. 4 allow a deflection of the gas flow along a uniformly conical design, the geometry of the structural elements 22 can optionally also be designed convex or concave in order to better deflect the flow into the center of the attachment body 8.

[0034] In the Fig. 5 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector for blowing in a gaseous medium according to a second embodiment, wherein Fig. 6 a sectional view through the attachment body 8 along a section line VI-VI in Fig. 5. The major difference from the previously described embodiment is that the structural elements 22 are bent or curved toward the outlet 19. This concave flow contour can be designed in a blade-like manner and, particularly toward the outlet 19, can impart a significant radial component to the gas flow radially inward.

[0035] The angles or contours of the structural elements 22 can either be kept the same within an attachment body 8 or optionally also vary, so that different jet angles of partial gas flows can be generated at individual structural elements 22 due to different geometries and angles of inclination within one and the same attachment body 8.

[0036] To achieve the desired flow effect, the attachment body 8 should have a certain axial extension, which allows at least one structural element 22 with the axial length l to achieve the inner contour 9 to be accommodated. The length l should be in a ratio of 0.2 < l / d < 1, preferably in a ratio of 0.3 < l / d < 0.5, to the inner diameter d of the attachment body 8 in the region of the end section 6 of the valve closing element 5. In absolute terms, the length l can be, for example, ≥ 2 mm.

[0037] The circumferential segment widths of the structural elements 22 are ideally between 30° and 70° and can also vary on one and the same attachment body 8. The contouring can also vary from structural element 22 to structural element 22 on one and the same attachment body 8.

[0038] The inventive concept allows for particularly great flexibility in the design of the spray pattern. The gas flow can be distributed very evenly throughout the entire combustion chamber 20, which improves mixture formation and increases efficiency. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2021 206 438 A1

[0003] WO 2023 / 001384 A1

[0004]

Claims

[1] Injector (1) for injecting a gaseous medium, in particular a gaseous fuel, preferably hydrogen, into a combustion chamber (20) of an internal combustion engine, comprising an axially movable valve closing element (5) for opening and closing at least one opening on a sealing seat (7), an actuator (21) for actuating the valve closing element (5), and a flow influencing geometry (10) arranged downstream of the sealing seat (7), characterized by , that the flow influencing geometry (10) downstream of the sealing seat (7) results in the form of an inner contour (9) segmented over the circumference, in which at least one structural element (22) is provided which, running in the downstream direction over its axial length (l), enables a radially inwardly directed flow deflection up to an outlet (19). [2] Injector according to claim 1, characterized bythat between two and eight structural elements (22) are arranged distributed over the circumference. [3] Injector according to claim 1 or 2, characterized by that a uniform distribution of the structural elements (22) over the circumference is provided, in which the structural elements (22) have an identical contour and an identical circumferential segment width. [4] Injector according to claim 3, characterized by that the structural elements (22) and the intermediate regions lying therebetween have a largely identical circumferential extent. [5] Injector according to claim 1 or 2, characterized by that individual structural elements (22) differ from one another with regard to contouring and / or circumferential segment width. [6] Injector according to claim 3 or 5, characterized by that the circumferential segment widths of the structural elements (22) are between 30° and 70°. [7] Injector according to one of the preceding claims, characterized bythat the flow influencing geometry (10) tapering in the flow direction is produced by conically extending or convexly or concavely curved structural elements (22). [8] Injector according to one of the preceding claims, characterized by that the axial length (l) of the at least one structural element (22) is in a ratio to the inner diameter (d) of the inner contour (9) directly downstream of the valve closing element (5), for which the following applies: 0.2 < l / d < 1, preferably 0.3 < l / d < 0.

5. [9] Injector according to one of the preceding claims, characterized by that the flow influencing geometry (10) arranged downstream of the sealing seat (7) is realized in a cap-shaped attachment body (8), in particular a blow cap. [10] Injector according to claim 9, characterized by that the cap-shaped attachment body (8) can be attached to a spray-side end of the injector (1), in particular to a nozzle body (2). [11] Injector according to one of the preceding claims, characterized by that the valve closing element (5) is part of an axially movable valve needle, wherein the valve closing element (5) has an end section (6) which is largely plate-shaped.

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