FI127022B - Two-stroke internal combustion engine and method of operating it - Google Patents

Description

Two-stroke internal combustion engine and method of operating it

The invention relates to a two-stroke internal combustion engine machine according to the preamble of claim 1. The invention further relates to a method for operating a two-stroke internal combustion engine machine according to the preamble of claim 2.

From DE 20 2004 002 185 U1 there is known a two-stroke internal combustion engine with several cylinders which is suitable for diesel operation. Each cylinder has a passageway provided with a movable piston in the passageway, the piston being mounted on a piston rod which is connected by a cross member and a connecting rod to the crankshaft pin. According to this state of the art, at the bottom of each cylinder passageway there are provided supercharging air inlets, also called flushing openings, whereby the respective cylinder piston releases each of the supercharged air inlets at the lower dead end or at the lower dead end of the piston. Further, it is already known in the prior art that at least one exhaust valve for exhaust gas and at least one main injector for supplying fuel via the main fuel or to the main fuel for compressed compressed air for diesel operation at relatively high pressure in the respective combustion space of the respective cylinder, thus when the piston is located in the region adjacent to the upper piston dead point of the piston. Self-ignition of fuel for diesel operation occurs. Two-stroke internal combustion engines suitable for this type of diesel use, which use especially heavy fuel oil as diesel fuel and typically come in the form of so-called large diesel engine engines in container ships or the like, emit relatively large amounts of nitrous oxides and soot with high emission limits. Therefore, there is a need for a two-stroke internal combustion engine, which emits less nitrogen oxides and soot and can also comply with stricter emission limits. Henceforth, the invention is based on the task of creating a new type of two-stroke internal combustion engine and a method for operating it. This task is solved by a two-stroke internal combustion engine machine according to claim 1. In accordance with the invention, the cylinders are operable in addition to diesel operation, or at least alternatively in pure gas operation, to this end each cylinder is provided with at least one gas inlet for supplying gas for gas operation, in particular natural gas, to the respective cylinder. in the adjacent location so that the fuel for gas operation can be supplied to the compressed air at relatively low pressure in the respective combustion space of the respective cylinder.

The two-stroke internal combustion engine machine according to the invention is thus not only available for diesel operation but also for pure gas operation in addition to diesel operation. In gas, in particular, natural gas can be used as a fuel that can be burned cleaner than, for example, heavy fuel oil, which can reduce the emissions of a two-stroke engine compared to diesel.

To ensure gas operation, each cylinder is provided with at least one gas inlet through which fuel can be supplied to the respective cylinder for gas operation, namely when the piston of each cylinder is located at and / or near the lower dead center of the piston. Fuel for gas operation can be introduced into the compressed air at relatively low pressure in the respective combustion space of the respective cylinder. This has the advantage that the formation of the mixture for gas operation in the combustion space of the respective cylinder takes place at relatively low pressure, so that there is no need to compress the fuel for gas operation outside the cylinder to high pressure. The fuel supply system for the gas fuel will then only need to be operated at relatively low pressures, which will result in a system as opposed to a fuel injection system operating at relatively high injection pressures and bringing the gas to the gas analogously to the top of the respective cylinder. at relatively high pressure in the respective combustion chamber of the respective cylinder, the lower safety requirements must be met and it is simpler in its technical implementation.

The gas inlet or each gas inlet through which fuel for gas operation can be fed into the respective cylinder is provided at the bottom of the passage of the respective cylinder.

When the gas inlet or each gas inlet is disposed in the lower portion of the passageway, the orifice in the upper region of the respective cylinder to which at least one outlet valve and at least one main injector is already fitted, no structural space, thereby simplifying the structural modification of the invention.

Each cylinder is further provided with at least one pilot injector through which, in the case of gas operation, for external ignition of the compressed compressed-air mixture for gas operation, the diesel fuel can be supplied at relatively high pressure to the combustion-fueled gas supply of the respective cylinder.

In gas operation, the charge air / fuel mixture is ignited by external ignition, for which diesel fuel is introduced through at least one pi-Lotti injector at a relatively high pressure in the respective combustion space of each cylinder for gas operation. Through the pilot injector or each pilot injector, the diesel fuel required for external ignition can be dispensed more accurately than through the main injector or each main injector for diesel operation. Thus, it is possible to accurately dispense the diesel fuel supplied through the pilot injector or each pilot injector for external ignition, thereby minimizing emissions in gas operation.

The method for operating a two-stroke internal combustion engine machine according to the invention is defined in claim 2.

Preferred embodiments of the invention will be apparent from the dependent claims and the following description. Embodiments of the invention will be described, without being limited, by way of illustration. Figure 1 is a schematic view of a first embodiment of a two-stroke internal combustion engine of the invention, Figure 2 is a schematic cross-sectional view of the two-stroke internal combustion engine of Figure 1 taken along section line A-A of Figure 1.

Figures 1 and 2 show schematic views of a two-stroke internal combustion engine 10 according to the invention in the area of its cylinder 11, wherein the two-stroke internal combustion engine 10 or its cylinders 11, on the other hand, are available for diesel and diesel fuel use. Each cylinder 11 of the two-stroke internal combustion engine 10 according to the invention has a passageway 12 into which the piston 13 is received movably. The piston 13 in the passageway 12 moves back and forth between the upper dead center and the lower dead center of the piston. The piston 13 is mounted on the piston rod 14 and engages via the piston rod 14 typically by analogy to DE 20 2004 002 185 U1 to the connecting rod and through the connecting rod to the crankshaft pin.

From Figure 1, it can be seen that a plurality of charge air inlets 16 are provided in the lower portion 15 of the passage sleeve 12, whereby the charge air inlets 16 are then distributed over the circumference of the passage sleeve 12. Through the charge air inlets 16, when the piston 13 of the respective cylinder 11 releases the charge air inlets at the lower dead center of the piston 13 or in the area adjacent to the lower dead point, the charge air in the the charge air to be introduced is made available for use in one or more of the charge air collector 18 of the exhaust gas compressor not shown in detail.

At least one exhaust valve 20 for the exhaust gas and at least one main injector 21 for supplying fuel to the diesel fuel for each of the cylinders 11 can be introduced into the compressed compressed air already under relatively high pressure in the combustion space 17 of the respective cylinder 11, thus when the piston 13 is located at or near the upper dead center.

In diesel operation, the fuel injected into the combustion chamber 17 of the respective cylinder 11 is spontaneously ignited for diesel operation, in which case heavy fuel oil is used for the diesel fuel operation.

The two-stroke internal combustion engine machine according to the invention, namely its cylinders 11, is not only suitable for diesel operation but, alternatively, for gas operation in addition to diesel operation. To this end, each cylinder 11 is provided with at least one gas inlet 22 through which fuel for gas operation, in particular natural gas, can be supplied to the respective cylinder 11, namely to the combustion space 17 of the respective cylinder 11, namely the piston 13 of the respective cylinder 11. in the lower dead center and / or in the area adjacent to the lower dead center so that the fuel for gas operation can be introduced into the compressed air at relatively low pressure in the respective combustion space 17 of the respective cylinder 11.

Accordingly, the fuel supply system for gas operation is effected at relatively low injection pressures for the gas fuel, particularly for natural gas, since, as already mentioned, gas for gas operation is introduced at the lower piston dead center and / or near the lower dead end site. Thus, for gas operation of the fuel supply system, only minor safety requirements need to be met, and it can also be implemented more simply than hitherto.

According to a preferred further development of the invention, the gas inlet or each gas inlet 22 through which gas is supplied to the respective cylinder 11 of the two-stroke internal combustion engine 10 for gas operation is fitted to the lower part of the the lower portion 29 of the passageway 12 then corresponds to the lower portion 15 of the passageway 12.

Thus, Figure 2 illustrates an exemplary embodiment in which the three functions of the charge air inlets 16 distributed around the circumference of the passageway 12 are modified as gas inlets 22, namely by providing a separate gas valve 23 in each of the charge air inlets 16 now operating as gas inlet 22. operating charge inlets 16 and connected thereto a radially outwardly extending gas passage 24 of the cylinder 11 or passage 12 through which fuel can be supplied for gas operation from the fuel supply system 25 of the two-stroke combustion engine 10 for gas operation.

A gas duct 24 fitted to each cylinder 11 communicates with a gas supply fuel system 24 common to all cylinders 11 via a gas line 26.

Unlike the embodiment shown in Figs. 1 and 2, it is also possible that the gas inlets 22 of each cylinder 11 are provided with a common gas valve, which can then be integrated, for example, into the gas line 26.

When, as in the embodiment of Figs. . For this purpose, only some of the charge air inlets 16, which then serve as gas inlets 22, need to be fitted with gas valves 23 and connected to a fuel supply system 25 for gas operation.

The ignition of the charge air-fuel mixture for gas operation occurs, unlike diesel operation, not through this self-ignition, but vice versa by external ignition, for which each cylinder 11 is further fitted with at least one pilot injector 27 through which for ignition, the diesel fuel can be introduced at relatively high pressure into the respective combustion chamber 17 of the respective cylinder 11 into a compressed gas-fuel mixture.

In Figure 1, the pilot injector 27 is then fitted to the upper part 19 of the cylinder 11, whereby the pilot injector or each pilot injector 27 can be used for more accurate metering of fuel, namely diesel fuel, through the main injector or each main injector 21. Thus, for the external ignition of the compressed air-fuel mixture in gas operation, a well-defined, low amount of diesel fuel can be fed into the compressed air-fuel mixture, whereby the amount of diesel fuel required for external ignition is reduced to an absolute minimum. In this way, it is also possible to reduce emissions in the use of gas.

Fig. 3 shows another embodiment of a two-stroke internal combustion engine 10 'having the basic structure corresponding to the two-stroke internal combustion engine 10 of Figs. 1 and 2, therefore the same reference numerals are used for the same machine part groups.

In the following, only the details in which the embodiment of Fig. 3 differs from the embodiment of Figs. For all other details, reference is made to the implementation of the embodiment of Figures 1 and 2.

In the embodiment of Figure 3, the gas inlets 22 are in turn disposed in the lower part of the passage 12 of the respective cylinder 11, however, the gas inlets 22 are This embodiment has the advantage that all the charge air inlets 16 are available for supplying charge air so that the amount of charge air that can be introduced into the combustion space 17 of the respective cylinder 11 is not limited by the gas inlets 22. The additional advantage of this formation is that then through the gas inlet or each gas inlet 22 of the gas then to the combustion chamber 17 at a relatively low pressure inside, when the charge air inlets 16 are again closed by the piston 13 so that There is no risk that gas may enter through the gas inlets 16 from the combustion chamber 17 into the area of the exhaust air collector 18. However, even in the embodiment of Figures 1 and 2, there is hardly any risk that the gas may escape from the combustion chamber 17 into the area of the charge air collector 18.

The internal combustion engine 10 or 10 'according to the invention is accordingly usable both in diesel and in gas.

In the diesel-powered operation of a two-stroke internal combustion engine 10 or 10 ', diesel fuel, in particular heavy fuel oil, is already introduced into the compressed charge air at relatively high pressure or at relatively high pressure through the main .

In the gas operation of the two-stroke internal combustion engine 10 or 10 ', the fuel for gas operation, in particular natural gas, is not yet or only insufficiently compressed in the compressed air at relatively low pressure or at relatively low pressure in the cylinder 11.

In diesel operation, the gas inlets 22 of the cylinder 11 are closed or the gas valve of each cylinder 11 or each gas valve 11 is closed. In diesel operation, the fuel for diesel operation is preferably further supplied to the main injectors 21 also through the pilot injector of each cylinder 11 or each pilot injector 27 into the combustion space of the respective cylinder 11 to prevent the pilot injectors 27 from closing in diesel operation.

In gas operation, the gas inlets 22 are active, while the main injectors 21 of the cylinders 11 are inactive. Only the pilot injectors 27 of the cylinders 11 are active in the gas operation of the two-stroke internal combustion engine 10 or 10 'for external ignition of the supercharged fuel mixture for the gas operation to bring the diesel fuel into the combustion space of the cylinders. Mon-fuel mixture.

According to the invention, according to the invention, in gas operation, fuel for gas operation, in particular natural gas, is introduced into the lower dead center region of the respective piston 13 into the respective cylinder 11. This may occur at relatively low pressure 17 there is relatively little pressure. In addition, a good distribution of the fuel for gas operation in the supercharged air as the piston 13 moves in the direction of the dead center is thereby ensured to ignite the supercharged-fuel mixture to provide a homogeneous mixture. As already mentioned above, the homogeneous compressed compressed-air fuel mixture for gas operation is supplied via at least one pilot injector 27 with diesel fuel for external ignition, namely in or near the upper dead center of the respective piston 13.

However, the injection pressure required to supply the fuel for gas operation is somewhat higher than the charge air pressure so that the safety requirements for the gas supply fuel supply system 25 are low.

The geometric arrangement of the gas inlet openings 22 and gas valves 23 in the lower part 15 or 29 of the passageway 12 of the cylinders 11 has the advantage that the main injector 20 or each outlet valve 20, the main injector or each main injector 21 and the pilot injector each pilot injector 27, no additional space is needed to supply fuel for gas, in particular for natural gas.

Claims (2)

A two-stroke internal combustion engine machine with a plurality of diesel-driven cylinders (11), wherein each cylinder (11) comprises a passageway (12) provided with a piston (13) movable within the passageway (12), with a supercharged lower part of the passageway (12). inlets (16) through which, when the piston (13) of the cylinder (11) releases the charge air inlets (16) at or below the dead center of the piston (13), the charge air is supplied to the passage (12) of the cylinder (11) at least one exhaust valve (20) for exhaust gas and at least one main injector (21) for supplying fuel for diesel, e.g. heavy oil, already compressed to the compressed air at relatively high pressure in the cylinder combustion space, is provided at the top (19) of each cylinder (11), the cylinders (11) are available for diesel operation or alternatively in gas operation, for this purpose at least one gas inlet (22) is provided to each cylinder through which fuel for gas operation, in particular natural gas, can be supplied to the cylinders (12) when the cylinder piston is in the vicinity of the dead point, so that fuel for gas can be supplied to the compressed air at relatively low pressure in the cylinder combustion space, so that the gas inlet or each gas inlet (22) through which the fuel can be supplied to the gas in the cylinder (11) 12) at the lower part (29) that each cylinder (11) is further provided with at least one pilot injector (27) through which the diesel fuel can be introduced into the cylinder (11) for external ignition of the compressed compressed-air mixture at relatively high pressure. ) in the combustion space (17) for the charge air-fuel mixture that the gas inlet or each gas inlet (22) through which fuel for gas use can be fed into the cylinder (11) above the charge air inlets (16) through which the charge air , is mounted in the cylinder passageway (12), and each gas inlet (22) of each cylinder is provided with a separate gas valve (23). A method for operating a multi-cylinder two-stroke internal combustion engine, in particular a two-stroke internal combustion engine according to claim 1, wherein the two-stroke , characterized in that, in gas operation, the fuel for gas operation, in particular natural gas, is not yet or only slightly compressed charge air at relatively low pressure into the cylinders; that in the case of diesel-powered inactive gas inlets, the main via orifices and preferably also through pilot injectors into the cylinders, in contrast to gas in the case of inactive main injectors, fuel for gas is supplied through the gas inlets and for external ignition through the pilot injectors into the cylinders. claim