Hydrogen internal combustion engine

Abstract

The present invention relates to a hydrogen internal combustion engine, comprising a cylinder (3) having a central axis X-X and having a cylinder head (4), which define a combustion chamber (5), and comprising a hydrogen injector (7), arranged in the cylinder head (4), for injecting hydrogen directly into the combustion chamber (5), wherein the hydrogen injector (7) is installed eccentrically with respect to the cylinder (3) in a manner deviating from the central axis X-X, and wherein the hydrogen injector (7) has a central axis Y-Y which, on account of an oblique installation position on the cylinder head (4), runs at an angle (β) to the central axis X-X of the cylinder (3). According to the invention, the hydrogen injector (7) has, at its downstream end facing the combustion chamber (5), an attachment body (8) with an outflow opening (17), wherein the outflow opening (17) has at least two opening sections which follow one another in the flow direction and have different orientations, wherein the second opening section directed towards the combustion chamber (5) is an oblique section (28) which runs at an angle (α) to the central axis X-X and thus defines a jet direction angle. An optimised position of the hydrogen injector (7) for stable jet guidance can be defined via the angles (α, β) and a distance (s) of the hydrogen injector (7) from the central axis X-X of the cylinder (3).

Description

[0001] R.417008

[0002] Description

[0003] title

[0004] Hydrogen combustion engine

[0005] State of the art

[0006] The present invention relates to a hydrogen internal combustion engine with an improved system layout for improving mixture formation between hydrogen and oxygen in a combustion chamber during direct injection of hydrogen into the combustion chamber, in particular to ensure stable jet guidance and robust ignition of the hydrogen in the combustion chamber in all operating situations.

[0007] There are currently increased efforts in the art to use hydrogen as a fuel for internal combustion engines. In particular, direct injection of hydrogen into the combustion chamber of the internal combustion engine is a promising concept. A problem here is achieving robust ignition of a hydrogen-oxygen mixture, especially under varying external conditions.

[0008] From DE 10 2021 206 438 A1, a gas nozzle for a gas valve is already known, comprising a nozzle body that is at least partially hollow and cylindrical, forming a sealing seat over which a gas flow path leads. Furthermore, the gas valve has a stroke-movable valve closing element with R.417008, which is partially incorporated in the nozzle body.

[0009] - 2 - an end section which is arranged outside the nozzle body and has a sealing contour that 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 limits the gas flow path downstream of the sealing seat, wherein 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.

[0010] Another injector for injecting a gaseous medium is also known from WO 2023 / 001384 A1. The blowing cap, which can be mounted on a nozzle body, has a sleeve-shaped base with a circumferential outer surface that transitions into a bottom section at the downstream end. The bottom section is designed such that at least one obliquely or asymmetrically blowing outlet opening is provided, and furthermore, the bottom section incorporates a flow-guiding section directed inwards towards the valve closing element, opposite to the flow direction, which deflects the flow of the gas to be blown out.

[0011] Disclosure of the invention

[0012] The hydrogen combustion engine according to the invention, with the features of claim 1, has the advantage that stable ignition is possible in all operating situations of the hydrogen combustion engine when hydrogen is directly injected into a combustion chamber of the hydrogen combustion engine. The hydrogen combustion engine has a surprisingly simple and cost-effective design. R.417008

[0013] - 3 -

[0014] According to the invention, this is achieved by the hydrogen internal combustion engine comprising a cylinder with a central axis XX and a cylinder head, which define a combustion chamber of the hydrogen internal combustion engine. Furthermore, the hydrogen internal combustion engine comprises a hydrogen injector for injecting gaseous hydrogen directly into the combustion chamber. The hydrogen injector has an attachment body with an outlet opening at its downstream end facing the combustion chamber, wherein the outlet opening has at least two successive opening sections in the flow direction, having different orientations, the second opening section facing the combustion chamber being an inclined section that runs at an angle to the central axis XX and thus defines a jet direction angle.The angles and distance of the hydrogen injector to the central axis XX of the cylinder allow for a particularly advantageous definition of an optimized position of the hydrogen injector for stable jet guidance.

[0015] Regardless of the operating point or charge movement, a targeted positioning of a hydrogen injector with an optimized attachment body (blowing cap) to the combustion chamber is ideally enabled for optimized stable jet guidance.

[0016] The dependent claims describe preferred embodiments of the invention.

[0017] Brief description of the drawings

[0018] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows: R.417008

[0019] - 4 -

[0020] Figure 1 is a schematic sectional view of a hydrogen internal combustion engine according to a first preferred embodiment of the invention and

[0021] Figure 2 shows a schematic sectional view of a hydrogen internal combustion engine according to a second preferred embodiment of the invention.

[0022] Embodiments of the invention

[0023] Several embodiments of the invention are described in detail below, wherein identical or functionally identical parts are designated with the same reference numerals.

[0024] Figures 1 and 2 each show a hydrogen combustion engine 1 according to a first and a second preferred embodiment of the invention in detail.

[0025] The hydrogen internal combustion engine 1 comprises a cylinder 3 with a central axis XX and a cylinder head 4 arranged on the cylinder 3. The cylinder 3 and the cylinder head 4 define a combustion chamber 5 of the hydrogen internal combustion engine.

[0026] The hydrogen combustion engine 1 further comprises an ignition source (not shown), e.g., a spark plug, and a hydrogen injector 7. The hydrogen injector 7 is configured to inject gaseous hydrogen into the combustion chamber 5. The ignition source is configured to ignite a mixture of injected hydrogen and oxygen in the combustion chamber 5.

[0027] As can be seen from Figures 1 and 2, the hydrogen injector 7 is arranged on the cylinder head 4. Thus, the hydrogen R.417008

[0028] - 5 -

[0029] Internal combustion engine, a so-called direct-injection (externally ignited) internal combustion engine.

[0030] D=2R denotes the diameter of cylinder 3 in Figures 1 and 2. The diameter D of cylinder 3 ranges in absolute terms from 50 mm to 250 mm, with the smaller cylinder diameters corresponding to PC (Passenger Car) applications, while the larger cylinder diameters D apply to applications ranging from LCV (Light Commercial Vehicle) and CV (Commercial Vehicle) to off-road applications and LE (Large Engine).

[0031] Injection systems for the direct injection of a gaseous medium, especially hydrogen, but also CNG, methane, ammonia, or mixtures of the aforementioned gases, have the task of precisely controlling the metering and the injection direction of the gas jet(s) into the combustion chamber 5 via injection valves or, more generally, injectors 7. For this purpose, corresponding sleeves or injection caps 8, hereinafter generally referred to as attachment bodies 8, can be used on the injector 7. Furthermore, injection systems for (hydrogen) direct injection inherently require a large stroke for a valve needle 2 with a valve closing element 6. Designing the magnetic circuit (e.g., of a magnetic actuator) with 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, in some cases, also hazardous to health (e.g., FeCo).Therefore, improved beam guidance should also be used to achieve a reduction in magnetic force.

[0032] The core of the invention consists in designing the internal flow of the gaseous medium with as little loss as possible via an internal contour 9 of the cap-shaped attachment body 8 according to the invention, so that the R.417008 located below, i.e. downstream of the valve closing element 6

[0033] - 6 -

[0034] Back pressure is reduced, and at the same time the jet can be directed precisely into the combustion chamber 5. This defined inner contour 9 is specifically designed to improve mixture formation. Due to the highly variable contouring of the inner contour 9, a very flexible use of sleeves or attachment bodies 8 on injectors 7 in various combustion chamber geometries of internal combustion engines is possible.

[0035] Overall, the optimized jet-shaping cap geometry allows for improved charge movement with increased purging of residual gas and hydrogen in the internal volume of the attachment body 8. This results in a robustness measure against pre-ignition even with increased seat leakage for the hydrogen injector 7 during engine operation.

[0036] The inner contour 9 forms a flow-influencing geometry that is fluidically downstream of the valve seat of the hydrogen injector 7. The attachment body 8 is securely and reliably mounted to the hydrogen injector 7. Common joining methods such as pressing, welding, brazing, bonding, or combinations thereof can be used.

[0037] The flow control geometry generated by the inner contour 9 has a key geometric characteristic that primarily deflects the gas flow radially inwards in a downstream direction within the attachment body 8, in order to then discharge the gas to be blown out, in particular hydrogen, into at least one outlet opening 17. According to the invention, the outlet opening 17 extends in at least two successive opening sections in the flow direction, wherein a first coaxial section 27 and a second inclined section 28 are provided. R.417008

[0038] - 7 -

[0039] For the described and illustrated embodiments according to Figures 1 and 2, it generally applies that the attachment body 8 has a hollow cylindrical section in the area of ​​the sealing seat, to which an outflow region 16 with at least one outflow opening 17 is connected, which opens into an end face facing the combustion chamber 5. Ideally, the outflow region 16 has a trough-like section 22 immediately downstream of the sealing seat. Due to the specific internal contour 9, the medium flowing into the attachment body 8 is guided stably from the sealing seat and the flow velocity is largely maintained up to the inlet cross-section of the outflow opening 17. Such an adaptation in conjunction with different shapes of outflow openings 17 enables targeted shaping of the gas jet as well as optimized mixture formation in the combustion chamber 5.The resulting increased flow rate also reduces the back pressure in the internal volume of the attachment body 8, thus improving flushing and reducing the forces acting on the underside of the valve closing element 6.

[0040] The flow control geometry generated by the inner contour 9 has several essential aspects and geometric specifications. Downstream of the valve closing element 6, the inner contour 9 of the attachment body 8 is shaped such that the tapered, in particular conical, section 22 follows, which ensures a significant tapering of the inner contour 9 over a short axial length, thus advantageously contributing to the desired optimized flow result. The jet guidance from the sealing seat occurs via the inner contour 9 in the conical and overall trough-shaped section 22. With a relatively large angle of the conical section 22, a strong radially inward flow component is generated over a very short axial length, so that in this area immediately downstream of the valve closing element 6, flow guidance is achieved in R.417008.

[0041] - 8 - advantageously in the form of an "S-curve". Instead of the conical shape of section 22, this section 22 can also be slightly concave. The inner contour 9 ensures that a supercritical flow is guaranteed and that back pressures below the valve closing element 6 are limited.

[0042] The hydrogen injector 7 is installed off-center to the cylinder 3, deviating from the central axis XX, wherein the hydrogen injector 7 has a central axis YY which, due to an inclined installation position on the cylinder head 4, runs at an angle β to the central axis XX of the cylinder 3.

[0043] The object of the invention is to design a hydrogen injector 7 with an optimized attachment body 8, positioned precisely relative to the combustion chamber 5, enabling optimized and stable jet guidance regardless of the operating point or charge movement. The optimal positioning of the hydrogen injector 7 with the aforementioned attachment body 8 on the combustion chamber 5 is to be determined.

[0044] According to the invention, the hydrogen injector 7 is provided at its downstream end, facing the combustion chamber 5, with the attachment body 8 and the outflow opening 17, wherein the outflow opening 17 has at least two successive opening sections in the flow direction, having different orientations, wherein the second opening section directed towards the combustion chamber 5 is the inclined section 28, which runs at an angle α to the central axis XX and thus defines a jet direction angle, wherein an optimized position of the hydrogen injector 7 for stable jet guidance can be defined via the angles α, β and a distance s of the hydrogen injector 7 to the central axis XX. R.417008

[0045] - 9 -

[0046] The arrangement of the hydrogen injector 7 with its inclined installation position on the cylinder 3 at an angle β to the central axis XX of the cylinder 3, as well as the specific design of the attachment body 8 on the hydrogen injector 7 with a similarly inclined jet guidance coming from the inclined section 28 of the outflow opening 17 at an angle to the central axis YY of the hydrogen injector 7, but also at an angle a to the central axis XX of the cylinder 3, allow a large variability in the arrangement of the hydrogen injector 7 on the cylinder head 4.

[0047] The intersection of the axes at the transition between coaxial section 27 and inclined section 28 of the outflow opening 17 of the attachment body 8 represents the reference point for the positioning of the hydrogen injector 7 and is defined by the distance s to the central axis XX of the cylinder 3. The distance s to the positioning of the hydrogen injector 7 with attachment body 8 on the combustion chamber 5 is described by the ratio to the radius R of the cylinder 3.

[0048] The following two case distinctions can be made. The geometric relationships according to the invention result in the following associated specifications:

[0049] Implementation according to Figure 1: 0.6 x R > s > 0.01 x R, for angle β 1°...45°, for angle a = 0°...40°. Usually, a < β will hold.

[0050] Implementation according to Figure 2: 0.9 x R > s > 0.6 x R, for angle β: 1°...70°, for angle a = 0°...70°. Usually, a > β will hold.

[0051] The concept according to the invention 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 5, which improves mixture formation and increases efficiency.

Claims

R.417008 - 10 - Claims 1. Hydrogen internal combustion engine, comprising: at least one cylinder (3) with a central axis XX and a cylinder head (4) defining a combustion chamber (5), a hydrogen injector (7) arranged in the cylinder head (4) for injecting hydrogen directly into the combustion chamber (5), wherein the hydrogen injector (7) is installed off-center to the cylinder (3) and deviates from the central axis XX, wherein the hydrogen injector (7) has a central axis YY which, due to an inclined installation position on the cylinder head (4), runs at an angle (β) to the central axis XX of the cylinder (3), characterized in that the hydrogen injector (7) has at its downstream end facing the combustion chamber (5) an attachment body (8) with an outlet opening (17), wherein the outlet opening (17) has at least two successive opening sections in the flow direction, having different orientations,wherein the second opening section directed towards the combustion chamber (5) is an inclined section (28) which runs at an angle (a) to the central axis XX and thus defines a jet direction angle, and an optimized position of the hydrogen injector (7) for stable jet guidance can be defined via the angles (a, β) and a distance (s) of the hydrogen injector (7) to the central axis XX.

2. Hydrogen combustion engine according to claim 1, characterized in that the attachment body (8) on the hydrogen injector (7) is designed with an inner contour (9) such that a sealing seat of the R.417008 - 11 - Downstream of the hydrogen injector (7) is an outflow area (16) with a trough-like section (22) and the outflow opening (17), 3. Hydrogen internal combustion engine according to claim 1 or 2, characterized in that the successive opening sections of the outflow opening (17) of the hydrogen injector (7) are a first coaxial section (27) and a second inclined section (28).

4. Hydrogen combustion engine according to claim 3, characterized in that an intersection of the axes in the transition of coaxial section (27) and inclined section (28) of the outflow opening (17) of the attachment body (8) represents the reference to the positioning of the hydrogen injector (7) and thus the distance (s) to the central axis XX of the cylinder (3) is defined.

5. Hydrogen combustion engine according to claim 4, characterized in that when the hydrogen injector (7) is positioned in the range 0.6 x R > s > 0.01 x R, an angle (β) between 1° and 45° is provided for the inclined installation position of the hydrogen injector (7), wherein R is the radius of the cylinder (3).

6. Hydrogen combustion engine according to claim 5, characterized in that the angle (a) of the orientation of the inclined section (28) of the outflow opening (17) to the central axis XX a = 0°...40° applies.

7. Hydrogen combustion engine according to claims 5 and 6, characterized in that a < ß applies.

8. Hydrogen combustion engine according to claim 4, characterized in that when the hydrogen injector (7) is positioned in the range 0.9 x R > s > 0.6 x R, an angle (β) between 1° and 70° is formed for R.417008 - 12 - the inclined installation position of the hydrogen injector (7) is provided, where R is the radius of the cylinder (3).

9. Hydrogen combustion engine according to claim 8, characterized in that the angle (a) of the orientation of the inclined section (28) of the outflow opening (17) to the central axis XX a = 0°...70° applies.

10. Hydrogen combustion engine according to claims 8 and 9, characterized in that a > ß applies.

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