Patent ID: 12241401

DETAILED DESCRIPTION

In the context of the invention it can be provided, that for all embodiments, the supply line9to the pre-chamber4can be either branched off the intake manifold19and/or the intake port10. In the case of branching off from the intake port10, the pre-chamber4can be directly fluidically connected to the respective intake port10. It should be mentioned, that although not every drawing indicates the possibility regarding how the pre-chamber4can be supplied, any combination of the embodiments depicted in the drawings is conceivable.

FIG.1schematically shows a cylinder2of an internal combustion engine1in which a piston3is arranged so as to be movable along an axis of the cylinder2, whereby a main combustion chamber12is formed between the piston3, the cylinder head16, and the cylinder2. At its top dead center position, the piston3with the cylinder2forms the so-called compression volume.

The cylinder2may be designed as part of a cylinder liner and/or a crank case. For the purpose of embodiments of the present invention, such components are collectively referred to as cylinder2.

The intake port10can interface with the main combustion chamber12through an intake valve6.

The exhaust manifold11can interface with the main combustion chamber12through an exhaust valve7.

The intake valve6and the exhaust valve7can be actuated by the actuators8. Example actuators for the intake valve6and exhaust valve7are a camshaft or hydraulic devices.

It can be provided that at least one gas mixer22is arranged upstream of the intake port10, wherein by use of the gas mixer22a fuel-air-mixture (e.g., a mixture of air and natural gas) can be provided for the intake port10. Furthermore, at least one compressor can be arranged upstream of the intake port10, wherein the provided air or air-fuel mixture for the intake port10can be charged.

A pre-chamber4communicates with the main combustion chamber12via transfer passages17and has an ignition source13and a pre-chamber gas valve5in the form of a check valve, which is connected to a source for an air-gas mixture (as the air-fuel-mixture for the main combustion chamber12an the pre-chamber4). In this embodiment, the source for an air-gas mixture is provided by a gas mixer22(indicated by the dotted square). Additionally or alternatively, a further injector20could be provided for introducing a gaseous fuel to the intake port10.

The ignition source13is in this embodiment a spark plug.

In this exemplary embodiment, the intake port10itself serves as the source for the air-gas-mixture.

The supply line9, which is formed as a cavity in the cylinder head16realizes the source for the air-fuel-mixture for the pre-chamber4.

To regulate the quantity of air-gas-mixture that can be fed into the pre-chamber4, a throttle valve14is arranged in the supply line9in this exemplary embodiment.

Furthermore, a tempering device15is provided in the form of pre-heating by means of engine coolant, such as water, in order to keep the supply line9at a temperature that prevents condensation of the gas-air mixture.

In the intake port10, a fuel injector18is arranged—in this embodiment provided as a hydrogen injector—wherein the fuel injector18is configured to enrich the fuel, air, or air-fuel-mixture supplied to the main combustion chamber12with molecular hydrogen.

During the intake stroke, the pre-chamber4is supplied with the same—but not enriched—air or air-fuel-mixture as it is directed to the main combustion chamber12before hydrogen enrichment through the fuel injector18.

During the compression stroke, the enriched air or air-fuel-mixture of the main combustion chamber12is pressed into the pre-chamber4through the transfer passages17, wherein the enriched air-fuel-mixture of the main combustion chamber12is mixed with the fuel, air, or air-fuel-mixture of the pre-chamber4, wherein the same air-fuel-mixture is used for the air-fuel-mixture supplied to the pre-chamber4and air-fuel-mixture provided for the main combustion chamber12before enrichment.

FIG.2shows a further schematic representation of the parts of an internal combustion engine1, wherein the piston3comprises a particularly curved piston crown (top surface of the piston).

Furthermore, compared toFIG.1, inFIG.2a further fuel injector20is arranged upstream of the supply line9. This further fuel injector20is designed as a port injection valve introducing a gaseous fuel to the intake port11.

The remaining characteristics are analogous toFIG.1(which shows a piston4configured as flat piston).

FIG.3shows a further schematic representation of the parts of an internal combustion engine1. In the embodiment shown byFIG.3, the fuel injector18is arranged in the intake port10in flow direction upstream of the branch of the intake port10and the transfer passage17.

The intake port10is connected to an intake manifold19, wherein the intake manifold19provides an air-fuel-mixture (e.g., a mixture of air and natural gas) for the intake port10.

Intake manifolds19are used to provide air or an air-fuel-mixture for more than one main combustion chamber12(see alsoFIGS.4to9). In most cases, the intake manifold19fluidically connects the intake ports10with an air or air-fuel-mixture source, e.g., a gas mixer22.

The fuel injector18is, in this embodiment, provided as a hydrogen injector, wherein the fuel injector18is configured to enrich the air-fuel-mixture—provided by the intake manifold19—supplied to the main combustion chamber12with hydrogen.

During the intake stroke, the pre-chamber4is supplied with the air-fuel-mixture provided by the intake manifold19via the intake port10and the transfer passage17. During this procedure, the main combustion chamber12is also supplied with the (same) air-fuel-mixture provided by the gas mixer22via the intake port10.

During the intake stroke, the supply of the pre-chamber4is stopped by closing the throttle valve14. This could also be done by closing the pre-chamber gas valve5(or e.g., an alternative valve which could be arranged in the transfer passage17).

This stopping of a supply of the pre-chamber has to be timed in such a way that the pre-chamber4is only scavenged or supplied by an air-fuel mixture of the intake manifold19.

After stopping the supply of the pre-chamber4, the air-fuel mixture of the intake manifold19can be enriched by the fuel injector18, wherein the enriched air-fuel-mixture is supplied to the main combustion chamber via the intake port10.

It is not necessary to have this strict timing for stopping the supply of the pre-chamber4and starting the enrichment afterwards. It can also be provided that the enrichment is started during the supply of the pre-chamber4, wherein the supply of the pre-chamber4is stopped in the moment when the enriched air-fuel-mixture reaches the throttle-valve14or the pre-chamber gas valve5or shortly before. Therefore, it is possible (for a short time) that the enrichment and the supply of the pre-chamber4happen in parallel.

Furthermore, it would also be possible to enrich the air-fuel-mixture provided by the intake manifold19the whole time, wherein also the enriched air-fuel-mixture would be supplied to the pre-chamber4, wherein only a lightly enriched air-fuel-mixture could be supplied to the pre-chamber4and a more strongly enriched air-fuel-mixture is supplied to the main combustion chamber12.

This could be done—for example—by controlling the fuel injector18in such a way, that after providing the air-fuel-mixture of the pre-chamber4the injection volume supplied by the fuel injector18is increased (to provide an enriched air fuel mixture for the main combustion chamber12, having a lower ignition delay than the fuel of the air-fuel-mixture provided to the pre-chamber4).

FIG.4shows an embodiment according to embodiments of the invention, wherein a schematic representation of an internal combustion engine1comprising four main combustion chambers12is illustrated. The main combustion chambers12are provided with an air-fuel-mixture of a gas mixer22via an intake manifold19and intake ports10.

Additionally, a compressor23(illustrated by the dotted lines) can be arranged at the intake manifold19for providing charged boost pressure in the intake manifold19to increase the combustion efficiency. A compressor23can be part of a turbo charger or can be mechanically driven (e.g., by connecting the compressor23to the crankshaft of the internal combustion engine1). The compressor23could also be arranged downstream of the gas mixer22and/or can be provided with more than one compressor stage.

The supply line9for supplying the pre-chambers4with an air-fuel-mixture branches in this embodiment from the intake manifold19downstream of the gas mixer22and upstream of a single fuel injector21.

This single fuel injector21—in this embodiment provided as a hydrogen injector—is configured to enrich the air-fuel-mixture provided by the gas mixer22which is supplied to the main combustion chambers12. Using a single fuel injector21in the intake manifold19, high pressure injections can be performed to enrich the air-fuel-mixture supplied to the main combustion chambers12.

Furthermore, in the supply line9of the pre-chambers4, an optional additional fuel or air supply24can be provided. If desired, the additional fuel and/or air supply24can be used to modify the air-fuel-mixture supplied and/or ignited in the pre-chambers4.

FIG.5shows another embodiment according to the invention, wherein (compared toFIG.4) an additional fuel supply25for the main combustion chamber12is provided. Using this additional fuel supply25for the main combustion chambers12, an additional fuel (e.g., hydrogen) can be supplied to the intake ports10to enrich the air-fuel-mixture (and therefore decrease the ignition delay) supplied to the main combustion chambers12. As the fuel injectors18are provided close to the main combustion chambers12, a fast response regarding a change of the air-fuel-mixture of the main combustion chambers12can be achieved by varying the supply of the fuel injectors18.

Furthermore, in this embodiment, it is illustrated that the supply line9can also branch from the intake ports10upstream of the additional fuel supply25. Of course, the supply lines9can be provided for each pre-chamber4separately (as indicated inFIG.6). Optionally, the supply lines9for the pre-chambers can be branched off the intake manifold19, either in the form of a single rail or preferred that each pre-chamber4is fluidically connected to the intake manifold19via a separate supply line9.

InFIG.5, the compressor23is arranged downstream of an additional or optional gas mixer22(illustrated by the dotted lines).

FIG.6shows a further embodiment according to the invention, wherein (compared toFIG.5) the supply line9branches from the intake ports9. This embodiment generally corresponds withFIG.1.

FIG.7shows a schematic representation of an embodiment according to the invention, comprising fuel injectors18for every cylinder2, wherein the pre-chamber4supply line9for every pre-chamber4is branched off of the intake manifold19(optionally branched off the intake ports10), further comprising a fuel injector21(single port injection valve) in the intake manifold10downstream the branch of the pre-chamber supply line9.

The air or air-fuel-mixture (depending if the additional dotted illustrated gas mixer22is present and/or active) provided by the compressor23can be supplied from the intake manifold19by the supply line9to the pre-chambers4.

Downstream of the supply line9, a single fuel injector21is arranged in the intake manifold19for enrichment of the air-fuel-mixture or the air provided by the compressor23. This enriched air-fuel-mixture can further be enriched in the cylinder2individually by activating the fuel injectors18in the intake ports10, which intake ports10branch downstream of the single fuel injector21.

The supply line9can additionally branch from the intake ports10or the intake manifold19.

The remaining components and additional components correspond to the already mentioned ones of the previous Figures.

The embodiment shown byFIG.8mainly correspond toFIG.7excluding the arrangement of the single fuel injector21, which is arranged in the embodiment ofFIG.8upstream of the branch of the supply line9in the intake manifold19.

Also, with such an arrangement of the single fuel injector21, an air or an air-fuel-mixture (depending if the additional dotted illustrated gas mixer22is present) can be enriched, and the same enriched air-fuel-mixture can be supplied to the pre-chambers4and the main combustion chambers12, wherein the enriched air-fuel-mixtureis further enriched in the intake ports10by the fuel injectors18before it is supplied to the main combustion chambers12and/oris mixed with a further fuel or air by the supply24before it is supplied to the pre-chambers4.

USED REFERENCE SIGNS

1internal combustion engine2cylinder3piston4pre-chamber5pre-chamber gas valve6intake valve7exhaust valve8actuators9supply line10intake port11exhaust manifold12combustion chamber13ignition source14throttle valve15tempering device16cylinder head17transfer passages18fuel injector19intake manifold20further fuel injector (intake port)21single fuel injector (intake manifold)22gas mixer23compressor24additional fuel or air supply for the pre-chamber25additional fuel supply for the main combustion chamber