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 for actuating the valve closing element (5), and a flow-influencing geometry (10) arranged downstream of the sealing seat (7).According to the invention, the flow influencing geometry (10) is formed in an attachment body (8), wherein the attachment body (8) is cap-shaped and has a jacket region (21) and a base region (22), and the base region (22) is present as an annular peripheral edge of a through-opening (25), wherein the through-opening (25) is designed such that a plurality of differently geometric sections with conicities are present around the circumference, which serve to generate an asymmetric injection jet (17).

Description

Prior ArtThe 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. The invention relates in particular to an injector with which hydrogen can be injected directly into the combustion chamber of a mixture-compressing, spark-ignited internal combustion engine.Gas injectors are known from the prior art in different configurations. Because of cost advantages and improved environmental compatibility, gaseous fuels have become more popular recently. It is problematic here, in comparison with injectors for liquid fuels, that the quantity of gas to be injected takes up a much larger volume than an equivalent quantity of liquid fuel. This results in an increased stroke requirement of a closing element, which is usually actuated by a magnetic actuator. The design of the magnetic circuit using standard materials is very difficult or in some cases impossible because of the limited installation space. Materials with higher magnetic force are very expensive and in some cases harmful to health (e.g. FeCo).DE 10 2021 206 438 A1 already discloses a gas nozzle for a gas valve, which nozzle nozzle comprises a nozzle body which is at least partially hollow-cylindrical and forms a sealing seat via which a gas flow path leads. In addition, the gas valve has a valve closing element which is held in sections in the nozzle body and can move in a stroke manner, with an end section which is arranged outside the nozzle body and has a sealing contour which interacts with the sealing seat. In addition, the gas valve has a sleeve surrounding the nozzle body and the end section of the valve closing element, which sleeve delimits the gas flow path downstream of the sealing seat, wherein the gas flow path downstream of the sealing seat has a cross-sectional constriction for achieving the Venturi effect, in the region of which at least one intake duct opens. The sleeve is designed in the form of a blow cap which can be applied to the nozzle body.A further injector for blowing in a gaseous medium is likewise 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 lateral surface which merges at the downstream end into a base region. The base region is designed in such a way that at least one obliquely or asymmetrically blowing-off outlet opening is provided, wherein a flow guide section directed inwards towards the valve closing element counter to the flow direction is furthermore formed in the base region, said flow guide section carrying out a flow deflection of the gas to be blown out.Disclosure of the InventionThe injector according to the invention for blowing a gaseous medium, in particular a gaseous fuel, into a combustion chamber of an internal combustion engine, having the features of claim 1 has the advantage that an optimized gas flow in the injector is made possible by geometric design of a flow influencing geometry arranged downstream of the sealing seat, so that the internal flow of the gaseous medium is designed as free of losses as possible via the inner contour of the cap-shaped attachment body, so that the dynamic pressure located below, i.e. downstream of, the valve closing element is reduced and at the same time the blowing jet can be introduced into the combustion chamber in a targeted manner.This is achieved according to the invention in that the injector has a valve closing element for opening and closing at least one opening at 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 and keep open the valve closing element by a stroke movement, while the valve closing element is closed by a spring force.The flow influencing geometry is advantageously formed in a cap body, wherein the cap body is designed in the form of a cap and has a jacket region and a base region, and the base region is present as an annularly encircling edge of a passage opening, wherein the passage opening is designed in such a way that a plurality of different geometric sections with conicityes are present circumferentially, which serve for generating an asymmetric injection jet.In a particularly advantageous manner, an injector according to the invention is provided which also makes possible an optimum filling of the combustion chamber with combustion gas, in particular when the injector is installed laterally on the combustion chamber. In addition, the combustion gas can mix well with the air in the combustion chamber. The combustion gas mixed better in this way burns with less pollutant and ensures better efficiency of the internal combustion engine.The injector according to the invention can generate a hollow-cone injection jet which, adapted to the corresponding installation conditions, can fill each combustion chamber with combustion gas in an optimized manner.Due to the small axial extension of the flow influencing geometry up to a lower end face of the valve closing element or only slightly beyond this, the heat absorbing surface is small. As a result, the attachment body heats up only slightly during the combustion phase. Thus, the risk of premature ignition of the fuel gas at the hot surface is again reduced. The transverse forces on the attachment body, which are produced by the flow deflection, act axially close to the sleeve-shaped base body. This results in a low bending load on this sleeve-shaped jacket region and on the fastening of the attachment body to the nozzle body. Advantages with regard to the precision or roundness, tightness of the seat region of the nozzle body, among other things, result from this.The dependent claims describe preferred developments of the invention.For an optimized design of the beam image, an extremely versatile variant frame is provided. Thus, the through-opening of the attachment body can extend in individual regions, viewed over the circumference, either conically widening, conically tapering or axially parallel, and in the process continue or cancel a conicity of the valve seat with a seat angle.The inner contour of the attachment body defined according to the invention can be advantageously accommodated with its special features in shape and design in attachment bodies with reducible external dimensions. This in turn allows a very flexible use of sleeves or attachment bodies on injectors in different combustion chamber geometries of internal combustion engines.In order to still assist a strong one-sided alignment of the fuel gas cone, the valve closing element can also have a deflection geometry in the region of its end section, which deflection geometry likewise deflects the flow in the desired direction. The end section is provided over its circumference with slopes, bevels or flattened portions of different sizes.The present invention is preferably used in injection systems directly injecting a combustion chamber. In particular, the injector is suitable for the direct injection of hydrogen into a combustion chamber of an internal combustion engine.DRAWINGPreferred embodiments of the invention will be described in detail below with reference to the accompanying drawings. In the drawing, the following is: FIG. 1 shows a schematic sectional view of the downstream valve end of an injector according to the invention for blowing in a gaseous medium according to a first exemplary embodiment, FIG. 2 shows a perspective illustration of an attachment body according to the invention for an injector according to the first exemplary embodiment, FIG. 3 shows a perspective schematic sectional view of the outflow-side valve end of an injector according to the invention for injecting a gaseous medium according to the first exemplary embodiment, FIG. 4 is a symbolic and idealised representation of the distribution of gas jet streams of an asymmetric steel pattern which can be achieved by means of the cap-shaped attachment body according to FIGS. 1 to 3, FIG. 5 shows a schematic sectional view of the downstream valve end of an injector according to the invention for blowing in a gaseous medium according to a second exemplary embodiment, FIG. 6 shows a schematic sectional view of an attachment body according to the invention for an injector according to a third exemplary embodiment, and FIG. 7 shows a symbolic and idealised representation of an asymmetrical beam pattern which can be achieved by means of the cap-shaped attachment body according to FIG. 6.Preferred Embodiments of the InventionThe invention relates to an injector 1 for injecting a gaseous medium, in particular hydrogen, into a combustion chamber 20, not shown in detail, of a spark-ignited internal combustion engine, for example a mixture-compressing spark-ignited internal combustion engine.FIG. 1 shows a schematic sectional view of the downstream valve end of an injector 1 according to the invention for injecting a gaseous medium according to a first exemplary embodiment.The injector 1 has a valve seat 3 with which a valve closing element 5 cooperates for opening and closing a sealing seat 7. The invention is directed to a flow influencing geometry 10 arranged downstream of the valve seat 3 in terms of flow technology, so that only the outflow-side valve end around this flow influencing geometry 10 is described in more detail. For the actuation of the injector 1, a magnetic actuator, not shown, is provided, for example, so that the injector 1 can be controlled in a targeted manner by this.The injector 1 also has a nozzle body 2 which, on the injection side, forms on the end side the already mentioned, for example conically shaped, valve seat 3 for the valve closing element 5 which opens outwards, that is to say opens in the direction of the combustion chamber 20. The valve closing element 5 is guided in an axially movable manner within the nozzle body 2, for example via a guide 18 (FIG. 3 ). In addition, the valve closing element 5 has an end section 6 in the form of a valve disk, which ultimately forms the sealing seat 7 in a manner corresponding to the valve seat 3. The two sealing seat partners valve seat 3 and valve closing element 5 are each metallic. The geometric and material design is effected in such a way that sufficient tightness is ensured during operation of a hydrogen engine. In the event of a fault, a shut-off system, which is fluidically connected upstream of the injector 1 for safety reasons and is not shown here, would ensure an interruption of the supply of the gaseous medium, in particular of the readily volatile hydrogen. The sealing contour of the end section 6 of the valve closing element 5 is, for example, rounded or conical, while the valve seat 3 on the nozzle body 2 has a conicity. However, other contours are also conceivable.The injection jet of an injector 1 for injecting fuel gas into the combustion chamber 20 of an internal combustion engine should be designed such that the fuel gas mixes in the best possible manner with the air in the combustion chamber 20. Injectors for blowing gaseous media are already known, having a valve closing element 5 which opens outwards and which blow a hollow-cone-shaped symmetrical fuel gas jet into the combustion chamber 20. In many applications, it is not possible on the cylinder head to arrange the injector 1 centrally on the combustion chamber 20 or on the main axis thereof. Rather, there are often requirements for a lateral arrangement, so that the alignment of the injector 1 must take place at an angle to the main axis of the combustion chamber 20.When using an injector 1 with a symmetrical injection jet and a lateral arrangement of the injector 1 on the combustion chamber 20, the gaseous fuel would only be blown into partial regions of the combustion chamber 20. The combustion gas is then insufficiently mixed with the combustion chamber air, which results in high raw exhaust gases (NOx) and poor engine operation.Therefore, the object of the invention is to provide an injector 1 which enables optimum filling of the combustion chamber 20 with combustion gas even when the injector 1 is installed laterally on the combustion chamber 20. In addition, the combustion gas should mix well with the air in the combustion chamber 20.The injector 1 according to the invention advantageously has an attachment body 8, which is of sleeve-shaped design and is securely and fixedly attached to the nozzle body 2 at the outflow-side valve end. The attachment body 8 can also be referred to as a "blow cap" and has a flow influencing geometry 10, which is distinguished in particular by a conicity which continues a conicity present on the nozzle body 2 by the valve seat 3 in a manner widening in the flow direction. In addition, the attachment body 8 is characterized in particular in that it represents a segment attachment nozzle in order to generate asymmetrical jet profiles. The attachment body 8 has a jacket region 21 and a base region 22, which extend substantially perpendicularly to one another, wherein the fixed connection to the nozzle body 2 takes place in the jacket region 21, and the base region 22 defines the flow influencing geometry 10 only as an annularly encircling edge of a passage opening 25.The base region 22 of the attachment body 8 is embodied in multiple segments, i.e. segment regions 24 of the through-opening 25 in the base region 22 of the attachment body 8 have angles U of different sizes over the circumference. In the exemplary embodiment shown according to FIGS. 1 to 3, six segment regions 24 are provided, which extend circumferentially over 60°, for example. However, an equally large circumferential extension of the individual segment regions 24 is not a requirement. A segment region 24a has an angle U1, two segment regions 24b following circumferentially on both sides have an angle U2, two segment regions 24c following circumferentially on both sides have an angle U3, and a segment region 24d opposite the segment region 24a by 180° has an angle U4 in the through-opening 25. Here, the same applies as U1>U2>U3>U4, which has the result that the gas flowing out via the segment region 24 awith the largest angle U1 experiences the greatest deflection. The angles U of the segment regions 24, 24 a, 24 b, 24 c, 24 dof the through-opening 25 in the base region 22 of the attachment body 8 have a size of 0° to 75° as half angle towards the valve longitudinal axis, since there is not necessarily a comparable inclination opposite.The attachment body 8 can ideally have, as a segment attachment nozzle, between two and twenty segment regions 24. The various angled segment portions 24 should have a flared contouring. Theoretically, however, segment regions 24 can also run without an angle, i.e. parallel to the valve longitudinal axis or even tapering conically.The seat angle S of the valve seat 3 on the nozzle body 2 is equal to or greater than the size of the largest angle U 1 of the attachment body 8 according to the invention, so that S>=U 1 applies. For a relatively large seat angle S, the desired large gas cross section at the valve seat 3 responds with an injector 1 opening with a specific stroke, which results in a high desired gas throughput.FIG. 4 shows a symbolic and idealised representation of the distribution of gas jet strands 27 of an asymmetric steel pattern in an imaginary section in front of the injector 1 through the combustion chamber 20, which can be achieved by means of the cap-shaped attachment body 8 according to FIGS. 1 to 3. The gas jet strands 27 a, 27 b, 27 c, 27 dare situated asymmetrically at different distances from the central axis of the injector 1 according to the size of the angle U 1, U 2, U 3, U 4 of the respective segment region 24 a, 24 b, 24 c, 24 dof the passage opening 25, or have unequally large spatial extents.The asymmetrically deflected fuel gas cone can, in the case of an injector 1 installed eccentrically or obliquely, uniformly fill the combustion chamber 20 with fuel gas when properly designed. Thus, the fuel gas also mixes uniformly with the entire air in the combustion chamber 20, and thus the combustion becomes low in pollutants and the internal combustion engine can be operated with good efficiency. In particular, little NOx arises during combustion. The exhaust gas after-treatment for reducing the NOx can thus be carried out more simply and economically.The attachment body 8 is firmly connected to the nozzle body 2 e.g. by means of welding, adhesive bonding, pressing or screwing. The attachment body 8 is made of metal or of ceramic. As an alternative to a chip-removing production, the attachment body 8 can also be produced using MIM technology (metal injection molding). Contouring may be done by sink erosion or ECM.The valve closing element 5 can have at its end section 6 towards the combustion chamber 20 a layer, not shown in detail, made of an insulating material such as e.g. ceramic or a ceramic composite material.FIG. 5 shows a schematic sectional view of the outflow-side valve end of an injector 1 according to the invention for injecting a gaseous medium according to a second exemplary embodiment. The attachment body 8 has a plurality of segment regions 24, which are formed so as to widen conically on the one hand and, opposite one another by 180°, so as to taper conically on the other hand. On the conically tapering side of the through-opening 25, there is thus a deflection geometry which guides the fuel gas flow downstream of the sealing seat 7 around the plate-shaped end section 6, with the result that on this side the flow is guided toward the valve longitudinal axis of the injector 1. On the conically widening side of the through-opening 25, the attachment body 8 even has a deflection angle U which is greater than the seat angle S, so that U1>S applies to this particularly strong deflection. This angle U can be, for example, up to 150°, viewed as the theoretical total angle.In order to still assist this strong one-sided alignment of the fuel gas cone, the valve closing element 5 also has a deflection geometry in the region of its end section 6, which deflection geometry likewise deflects the flow in the desired direction. The end section 6 is provided over its circumference with slopes, bevels or flattened portions of different sizes.FIG. 6 shows a schematic sectional view of an attachment body 8 according to the invention for an injector 1 according to a third exemplary embodiment. In this case, no individual segment regions 24 are provided which differ from one another in a distinct manner; rather, a deflection geometry which continuously changes in angle U is present over the circumference in the region of the through-opening 25. Angular orders of magnitude of the above-described embodiments can be applied to such a solution. Via the axial thickness of the base region 22, the angle U can theoretically also vary continuously or separated by edges at every circumferential location.FIG. 7 shows a symbolic and idealised representation of an asymmetrical beam pattern which can be achieved by means of the cap-shaped attachment body 8 according to FIG. 6. The asymmetrical steel pattern 27 can have an oval contour in section or, for example, an egg shape.For all variant embodiments, it applies that the valve end of the injector 1 with the attachment body 8 does not protrude into the combustion chamber 20 or protrudes into it with a slight axial overlap. Alternatively, the injector 1 can also be installed in the receiving bore for the injector 1 in a slightly retracted manner in order to transfer as little heat as possible to the injector tip. In this way, a robust and low-wear valve seat 3 can be created. The bottom region 22 of the sleeve- or cap-shaped attachment body 8 has an axial height which corresponds to about 5% to 70% of the diameter of the valve seat 3 for good ventilation. Thus, the axial end face of the attachment body 8 is approximately at the height of the end face of the valve closing element 5 or slightly above or below.Normally, sealing seats 7 on gas injectors are not perfectly tight in the closed state. There is a slight leakage of fuel gas. However, if the valve seat 3 is well ventilated, the exhausted fuel gas distributes and narrows well in the combustion chamber 20. This early combustion, before top dead center, effectively brakes piston motion. In addition to the unnecessarily burnt combustion gas, the pre-ignition means a very strong or damaging load of the piston, connecting rod and crankshaft.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2021 206 438 A1

[0003] WO 2023 / 001384 A1

[0004]

Claims

Injector (1) for blowing 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 valve seat (3), an actuator for actuating the valve closing element (5) and a flow influencing geometry (10) fluidically arranged downstream of the valve seat (3), characterized in that the flow influencing geometry (10) is formed in a cap body (8), wherein the cap body (8) is designed in the form of a cap and has a jacket region (21) and a base region (22), and the base region (22) is present as an annularly encircling edge of a passage opening (25), wherein the passage opening (25) is designed in such a way that a plurality of different geometric sections having conicityes are present circumferentially, which serve for producing an asymmetric injection jet (17).Injector according to Claim 1, characterized in that the attachment body (8) has, as a segment attachment nozzle, a plurality of segment regions (24, 24a, 24b, 24c, 24d) which are circumferentially successive and differ from one another geometrically or in contour in order to generate asymmetrical jet profiles.Injector according to Claim 1, characterized in that two circumferentially adjacent segment regions (24, 24a, 24b, 24c, 24d) have conicityes whose angles (U, U1, U2, U3, U4) differ.Injector according to Claim 1, characterized in that a segment region (24a) having the largest angle (U1) is formed in the through opening (25) opposite the segment region (24d) having the smallest angle (U4) by 180°.Injector according to one of Claims 2 to 4, characterized in that the attachment body (8) has, at the passage opening (25), between two and twenty segment regions (24, 24a, 24b, 24c, 24d) with at least two different angles (U, U1, U2).Injector according to one of Claims 2 to 5, characterized in that the angles (U) of the segment regions (24, 24a, 24b, 24c, 24d) of the through-opening (25) in the base region (22) of the attachment body (8) have a size of 0° to 75° as half angle towards the valve longitudinal axis.Injector according to Claim 1, characterized in that the attachment body (8) is designed in such a way that a deflection geometry which continuously changes in angle (U) is present over the circumference in the region of the passage opening (25) in order to generate asymmetrical jet profiles.Injector according to Claim 7, characterized in that the continuously changing angles (U) of the through-opening (25) in the base region (22) of the attachment body (8) have a size of 0° to 75° as half angle towards the valve longitudinal axis.Injector according to one of the preceding claims, characterized in that the through-opening (25) of the attachment body (8) runs either conically widening, conically tapering or axis-parallel and in the process continues or cancels a conicity of the valve seat (3) with a seat angle (S).Injector according to one of the preceding claims, characterized in that the cap-shaped attachment body (8) can be attached to an injection-side end of the injector (1), in particular to a nozzle body (2).Injector according to one of the preceding claims, characterized in 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 in the form of a disk.Injector according to Claim 11, characterized in that the valve closing element (5) has, at its end section (6) towards the combustion chamber (20), a layer made of an insulating material, such as e.g. ceramic or a ceramic composite material.

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