JPH11311122A - Two-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure relatively high environmental compatible nonpollutional properties and economical efficiency in an engine by a simply, inexpensively advantageous means, in the case of a two-cycle engine having a cylinder with an air supplying opening-slit device 4 for supplying a charging medium being controllable by a piston belonging to the cylinder, and an exhaust opening device being opened in an opening time span extending over the specified crank angle range, and for discharging the exhaust gas, especially in a two-cycle large-sized diesel engine. SOLUTION: An exhaust opening device has a plurality of exhaust ports 10, 11 and 12 with which three exhaust valve 13, 14 and 15 being separately operable with one another are affiliated, therefore these exhaust valves are opened during the partial opening times T10, T11 and T12 different from one another in an opening time span Ta, and further the whole exhaust gas quantity is divided into a plurality of exhaust gas partial flows V10, V11 and V12, and each of these exhaust gas partial flows is feedable to a different object spot, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cylinder having an inlet-slit arrangement for supplying a filling medium, which can be controlled by a piston belonging to the cylinder, and over a predetermined crank angle range. The present invention relates to a two-stroke engine of the type having an exhaust port for exhaust gas exhaust, which is open for an open time span (open duration), in particular a two-stroke large diesel engine.

[0002]

2. Description of the Related Art In known systems of the above type, for example in our two-cycle large diesel engine, the exhaust system has only one large exhaust valve. Thus, only one exhaust gas stream results, which contains all pollutants and environmentally harmful substances,
The mean temperature of the exhaust gas stream is significantly lower than the temperature of the expanding combustion gases discharged during the pre-exhaust period (opening of the exhaust valve before opening the inlet-slit device), and
Significantly higher than the temperature of the almost clean scavenging air that is exhausted during the post-exhaust period (inlet-exhaust period after closing the slit device).

[0003] Such a known device of the above-mentioned type therefore requires a relatively large group of devices for the purification of exhaust gases and the removal of toxic substances, which have a volume flow corresponding to the total amount of exhaust gas. Must be processed. However, this does not produce good results based on existing installation space conditions.

Further, since the average temperature of the exhaust gas is relatively low, a group of purification devices for purifying the exhaust gas containing nitrogen oxides is provided between the exhaust gas tank and the inlet of the turbocharger turbine. It is necessary to ensure that the catalytic treatment process takes place. If placed behind the turbocharger turbine, the temperature would be excessively low.

Furthermore, in this case, a part of the exhaust gas energy is lost. This is because the total amount of exhaust gas in the tank is reduced and the relatively high pressure in the cylinder drops to the pressure in the exhaust gas tank during pre-exhaust without being used for mechanical work. This has consequences for the overall economy. Such loss in pressure reduction means that in today's two-stroke diesel engines, the energy potential of almost 8% of the engine's shaft power is lost.

[0006]

It is therefore an object of the present invention, starting from such prior art, to provide engines of the type mentioned at the outset with a relatively high environmental friendliness (simple and cost-effective). Pollution-free) and economical efficiency.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided, in accordance with the present invention, an exhaust port device having a plurality of exhaust ports, each of which is associated with an exhaust valve which can be operated independently of one another. The exhaust valve is open during different partial opening times within the opening time span, and the total exhaust gas amount is divided into a plurality of exhaust gas partial flows, and each of these exhaust gas partial flows Can be supplied to different destinations.

With such measures, the disadvantages mentioned above are minimized or completely avoided. The division of the total exhaust gas volume into a plurality of exhaust gas substreams makes it possible, in an advantageous manner, to use the exhaust gas individually or in accordance with the characteristics of each exhaust gas substream, which results in high purification It is advantageous for achieving purity and good economy.

Advantageous refinements and improvements of the above measures according to claim 1 of the present invention are set out in the dependent claims. The outlet devices advantageously have at least two outlet groups, each having at least one outlet. This allows the optimization of the measures already in one direction or in the other direction with relatively little construction cost.

It is possible for the partial opening time of the at least one outlet to be at least partially, preferably completely, in accordance with the range after the closing control of the inlet-slit device. This exhaust gas partial stream has a relatively high cleanliness and a relatively low temperature. This exhaust gas partial stream can therefore be passed directly or indirectly through a separate cooling-purification device of the engine or through an engine-specific scavenging air cooler,
It can be fed to a slitting device and thus circulated. If the circulated exhaust gas partial stream is returned through the cooler, this enhances the scavenging performance of the engine, which in turn lowers the temperature at the start of the engine compression stroke and increases the efficiency of the engine. Since the cleanliness of the scavenging air is reduced by the circulation of this exhaust gas partial stream, the NO
The possibility of product generation is reduced. Further advantages are recognized in the following points. That is, the required amount of clean supercharged air sent through the compressor of the turbocharger is also reduced, thereby making the structure of the compressor compact. During this phase of the engine cycle, the intake-slit arrangement of the engine is closed, so that the upward movement of the compression stroke is advantageous in order to pump the exhaust gas into the supercharged air accumulator of the engine by pumping. work. If it is desired to increase the amount of exhaust gas circulation, the duration of the open time of the exhaust port is increased, so that the exhaust port is already closed before the intake-slit device of the engine is closed by the piston. It needs to be opened. For this purpose, furthermore, a compressor for conveying the exhaust gas in the system must be provided in the exhaust gas partial flow path. However, this compressor operates at a much lower pressure ratio than the turbocharger compressor, thus significantly reducing the power required to generate scavenging air (gas).

According to a further refinement of the invention, the partial opening time of the at least one exhaust valve is at least partially, preferably completely, of the inlet-slit arrangement. In the range before the opening control. During this time of the engine cycle, the exhaust gas stream and the supercharged air accumulator are not directly connected, so that the pressure in the associated exhaust gas tank is lower than the pressure in the supercharged air accumulator without backflow. Can be higher. This exhaust gas partial stream has a relatively high pressure and high temperature,
Therefore contains high energy. The relatively high pressure in the associated exhaust gas accumulator increases the potential for converting the energy in the exhaust gas into mechanical work.
This potential is used in practice in connected turbocharger turbines and / or power turbines. This exhaust gas stream, which is only a limited part of the total exhaust gas volume, also contains a large proportion of the total amount of pollutants and environmentally hazardous substances. Thus, a large portion of the total amount of engine pollutants and environmental pollutants is purified by relatively small devices, which are located before and after the turbocharger turbine. Because the temperature is still high enough, catalytic treatment is possible both before and after expansion in the turbine.

In each case, the partial opening time of the at least one exhaust valve at least partially corresponds to or lies in the range between the opening and closing control of the inlet-slit device. They can completely overlap. The exhaust gas partial stream generated in this case can advantageously drive a specific exhaust turbocharger, wherein the specific exhaust turbocharger has the abovementioned exhaust gas partial flow, that is, its partial opening time. With the exhaust gas turbocharger, which can be loaded at least partially by the exhaust gas partial flow before the opening control of the inlet-slit device, the filling air quantity required by the engine can be filled sufficiently.
This makes it possible to use the excess energy in the entire exhaust gas stream, advantageously for driving the power turbines connected in parallel in some way, thereby increasing the overall efficiency of the engine. Connecting the power turbines in parallel has the advantage that each power turbine can be relatively small.

[0013] Further advantageous refinements and improvements of the measures of the invention according to claim 1 are set out in the other dependent claims.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a schematic block diagram of the principle of a large-sized two-stroke diesel engine according to the present invention with a plurality of exhaust ports; FIG. 2 is a diagram showing the relationship between crank angle or time and exhaust gas volume flow and filling volume flow; It is.

The basic structure and mode of operation of a two-cycle heavy duty diesel engine, for example a two-stroke heavy duty diesel engine which can be used as a marine drive engine, are known per se and therefore need not be described in detail here. is there. Engines of this type generally have cylinders 1 arranged in parallel, of which only one cylinder 1 is shown as a representative in FIG. Each cylinder 1
A piston 2 cooperating with a crankshaft, not shown, which defines a combustion chamber 3. Fuel and air are supplied to the combustion chamber 3. Fuel (here, diesel oil) is injected into the combustion chamber. The injection device is not shown in FIG. 1 to make the drawing easier to see. The supply of air is effected via an air inlet arranged in the region of the cylinder wall-a slit 4 and the piston 2 is connected to the air inlet-
It passes through the slit in the range of the bottom dead center of the piston, and thereby controls the opening and closing of the intake port-slit.

The supercharged air is compressed using the energy of the exhaust gas. For this purpose, a device having two exhaust turbochargers 5, 6 is provided here, behind which a single supercharged air common to both exhaust turbochargers is provided. A cooler 7 is arranged, by means of which the temperature of the supercharged air is reduced. Cooler 7
Behind, a supercharged air accumulator 8 common to all cylinders 1 is arranged, from which branch conduits 9 extend to each cylinder 1.

Exhaust gas generated during combustion is pushed out of the combustion chamber 3 through a plurality of exhaust ports 10, 11, 12 arranged in the area of the cylinder head. In the illustrated example, three exhaust ports 10, 11, and 12 are provided. Each exhaust port 1
The exhaust valves 0, 11 and 12 can be opened and closed by exhaust valves 13, 14, and 15 respectively assigned to the exhaust ports. Each of the exhaust ports 10, 11, 12 is connected to each of the associated exhaust connection conduits 1.
Exhaust manifold pipe 1 belonging via 6, 17, 18
9, 20, 21 are connected. In this case, the corresponding exhaust ports 10 or 11 or 12 of all cylinders 1 are connected to the same exhaust manifold pipe 19 or 20 or 21, respectively.

The exhaust valves 13, 14, 15 can be operated independently of each other. The operating device provided for this purpose is not shown for the sake of clarity of the drawing. Exhaust valve 13,1
The control of this operating device of 4, 15 is designed such that the exhaust ports 10, 11, 12 of each cylinder 1 are opened sequentially. It is also possible for them to be opened in duplicate. Correspondingly, an opening time span indicated by Ta in the diagram of FIG. 2 occurs, during which the outlets 10, 11, 1
2 is opened. This open time span extends in this case back and forth beyond the time span indicated by Te, in which the inlet-slit device 4 is open. T in each case
It is also possible that the extension of Ta with respect to e is extended only in one direction before or after.

FIG. 2 shows the times t ₁ , t ₂ , t ₃ and t _{4 in which} the open time span Ta of the exhaust ports ₁₀ , ₁₁ and ₁₂ is divided into three partial open times T ₁₀ , T ₁₁ and T _12. It is shown. Among partially open time T _10, the exhaust valve 13 that belong to the exhaust port 10 is open. This time span completely or partially coincides with the time span in which the inlet-slit device 4, typically illustrated by the area-curve Ve, is open. Among partially open time T _11, the exhaust port 11
The exhaust valve 14 belonging to is open. Partial opening time T ₁₂
Inside, the exhaust valve 15 belonging to the exhaust port 12 is open. Multiple Correspondingly, three in this case, the exhaust gas partial flow, which is shown by curve V _10, V ₁₁ and V ₁₂ is generated in FIG. The lower surfaces of the curves each correspond to the associated open range of the exhaust valve. The charge volume flow supplied to the combustion chamber 3 through the inlet-slit 4 is the curve Ve
Indicated by

The outlet 10 is open during the scavenging of the combustion chamber 3 via the inlet-slit device 4, as described above. Exhaust gas partial flow V ₁₀ is the maximum of the exhaust gas partial flow Correspondingly. The exhaust gas partial stream serves to drive the first exhaust turbocharger 5. Correspondingly, the exhaust manifold pipe 19 is connected via line 22 to the turbine 5a of the exhaust turbocharger 5, and the compressor 5b of the exhaust turbocharger 5, as already described above, 2
3 is connected to a supercharged air cooler 7. In this case at the same time the power turbine 28 is driven by the exhaust gas partial flow (exhaust gas partial flow volume) V _10. This power turbine is arranged in a fluid-dynamic manner parallel to the turbine 5 a of the exhaust turbocharger 5 in order to achieve a small structure size in this example. A series arrangement is of course also possible.

As can be seen from FIG. 2, the exhaust port 11 is already opened before the start of the scavenging described above. Before the start of the scavenging of the combustion chamber 3, the exhaust gas has a relatively high temperature and a relatively high pressure, as well as a high pollutant content and an environmentally harmful content. Exhaust gas partial flow V ₁₁ belongs therefore has a relatively large amount of energy, this energy is used to drive Again exhaust turbo supercharger. In order to be able to make full use of this energy, one unique exhaust turbocharger, in this example the second
The exhaust turbocharger 6 is provided, and the turbine 6a is connected to the exhaust manifold pipe 20 via a conduit 24. The compressor 6 b of the exhaust turbocharger 6 is in this case connected via a conduit 25 to the supercharged air cooler 7. In this case too, as can be seen from FIG. 1, at least one additional, preferably parallel, power turbine 29 can be loaded with exhaust gas.

In the exhaust manifold pipes 19 and / or 20, it is possible to arrange catalysts, each of which comprises a soot filter and a NOx catalyst element. The amount of pollutants and environmentally harmful substances released into the atmosphere is therefore dependent on whether the catalyst is in both exhaust gas partial streams V ₁₀ and V
₁₁ or both, or only one of them, or neither of them.

[0023] When compared to the total quantity of exhaust gas, is small the amount of the exhaust gas partial flow V _11, however, as noted above, contains a large amount of pollutants and environmental toxins. Thus, by providing a relatively small catalyst in this exhaust gas partial stream, a significant reduction in the total amount of pollutants and environmentally harmful substances released into the atmosphere can be achieved. Furthermore, the temperature of the exhaust gas partial stream is high enough that the required catalysis takes place without problems in the catalyst arranged downstream of the turbine. According to this principle, 25% of the total exhaust gas stream
Catalytic treatment of less than 10% of the exhaust gas partial stream can reduce total pollutant emissions into the atmosphere by more than 50%.

[0024] In the example shown in FIG. 2, the span of the opening time for the exhaust gas partial flow V ₁₁ is the air supply opening - in front of the point where the slit 4 is controlled open. Thereby, as mentioned above, there is a higher pressure in the exhaust manifold pipe 20 than in the supercharged air accumulator 8, which increases the expansion work performed by the turbine 6a or 29. The total amount of pollutants and environmentally hazardous substances is 50
When further trying to reduce than percent, and a longer span of the opening time of the exhaust gas partial flow V _11, the span of the result the open time the air supply port - to overlap with the opening time span of the slit device 4 . Thus, the flow rate of the exhaust gas partial flow V ₁₁ increases, the amount to be processed by the catalytic action of the provided catalyst device in the exhaust manifold pipe 20 is increased.

The outlet 12 is opened after the scavenging process described above has been completed. Exhaust gas partial flow V ₁₂ belonging to the exhaust port 12 is therefore contained only relatively small contaminants, temperature is relatively low. Exhaust gas partial flow V ₁₂ is thus fed again into the combustion chamber 3 along with fresh charge air. This circulation of the exhaust gas partial flow reduces the required supercharging air volume, so that the exhaust turbochargers 5 and 6 can be manufactured with a relatively small construction size.

The exhaust gas partial stream V ₁₂ can be supplied directly to the supercharged air accumulator 8. In the illustrated example, the exhaust gas partial flow V _12, as indicated by a conduit 26 extending from an exhaust manifold pipe 21 to the boost air cooler 7, is supplied to the supercharger air cooler 7. In this case, it is also possible to use a specific cooler. The conduit 26 is disposed a cleaning device in the form of a soot filter 27, which removes fine particles (particulates rate) contained in the exhaust gas partial flow V _12. By using this principle,
That is, by directing the exhaust gas partial stream V ₁₂ through the supercharged air cooler 27 or through a separate cooler,
The total scavenging flow rate flowing through the inlet-slit device 4 can be increased, thereby improving the scavenging performance of the engine with cold air-cold exhaust gas and the cylinder 3 at the start of compression (closing of the exhaust valve 15). Inside temperature can be reduced. This reduced temperature at the start of compression results in improved efficiency of the engine work process.

[0027] In the example shown in FIG. 2, the opening time span of the exhaust gas partial flow V ₁₂ is the air supply opening - located after closed control point of the slit 4, so that the piston 2 is an exhaust port 12 to exhaust gas, exhaust The pressure can be sent to the supercharged air accumulator 8 via the manifold pipe 21, the soot filter 27, and the supercharged air cooler (scavenging air cooler) 7. Exhaust gas partial flow V ₁₂
Can be started before the closing control of the air inlet / slit device 4 in some cases, whereby the exhaust gas circulation amount can be increased. However, this requires that a suction blower 30, shown in broken lines in FIG. If a suction blower is used for the conduit 26, it is advantageous to provide a separate cooler 31 in front of the blower, as further shown in FIG.

The mixing of the clean supercharged air with the circulated exhaust gas reduces the temperature and the oxygen content of the cylinder charge at the beginning of the compression stroke, thereby reducing the NO during the combustion process.
The possibility of product generation can be reduced.

As mentioned above, the amount of fresh air passing through the compressors 5b and 6b is reduced compared to the amount passing through the compressor in a known device having only one common exhaust valve. ing. Furthermore, the amount of energy supplied to the reduced mass flow is substantially unchanged compared to known devices. This means that a larger amount of energy is needed to drive the compressors 5b and 6b than the turbine 5b.
a and 6a, which means that the amount of energy can be further used in the illustrated power turbines 28 and / or 29. The power turbine 28 or 29 can drive various device units such as a generator.

As can be seen from the above description, according to the means of the present invention, the characteristics of each exhaust gas partial flow can be utilized particularly effectively, and as a result, a high engine output can be achieved as a whole. it can. It is easily possible to increase the power of the engine by 3-5% compared to known engines having only one exhaust valve. In the example shown, three exhaust gas partial streams are provided, two of these exhaust gas partial streams occurring before or after the scavenging process.
Particularly good results are achieved in this case. However, it will already significant output increase only by providing a simple one or the other of the exhaust gas partial flow of the two exhaust gas partial flow V ₁₁ or V ₁₂ will be obtained.

In the example shown, one exhaust port is assigned to each exhaust gas partial stream. However, it is also conceivable to assign a group of outlets comprising a plurality of outlets to each exhaust gas partial stream. Similarly, it is also conceivable to cross the partial opening times.

The example shown is based on a two-cycle large diesel engine. However, the invention can also be used to advantage with other two-stroke engines, for example gas engines, diesel-gas engines, Otto-gas engines and Otto engines.

[Brief description of the drawings]

1 is a basic schematic block diagram of a two-cycle large diesel engine according to the present invention with a plurality of exhaust ports.

FIG. 2 is a diagram showing a relationship between a crank angle or a time and an exhaust gas volume flow and a filling volume flow.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 3 Combustion chamber 4 Supply port-slit device 5 Exhaust turbocharger 5a Turbine 6 Exhaust turbocharger 6a Turbine 7 Supercharged air cooler 8 Supercharged air accumulator 10, 11, 12 Exhaust port 13 , 14, 15 exhaust valve 19, 20, 21 an exhaust manifold pipe 26 conduit 27 gas purification device 28 turbine 29 turbine 30 air blower 31 cooler Ta opening time span T ₁₀ partially open time T ₁₁ partially open time T ₁₂ partially open time V ₁₁ gas partial flow V ₁₂ gas partial flow V ₁₃ exhaust gas partial flow

Claims (18)

[Claims] Cylinder (1) having an inlet-slit device (4) for supplying a filling medium, controllable by a piston (2) belonging to the cylinder (1).
An exhaust port for discharging exhaust gas, which is opened during an open time span (Ta) over a predetermined crank angle range;
A two-stroke engine, in particular a two-stroke large diesel engine, comprising: a plurality of exhaust ports (10, 11, 12);
And each of these exhaust ports has an exhaust valve (13, 14, 15) operable independently of one another, the exhaust valves being different from each other within an open time span (Ta). It is open only for the opening time (T ₁₀ , T ₁₁ , T ₁₂ ), and the total exhaust gas amount is a plurality of exhaust gas partial flows (V ₁₀ ,
V ₁₁ , V ₁₂ ), characterized in that these exhaust gas partial flows can be supplied to different destinations. 2. The two-stroke engine according to claim 1, wherein the outlet-device has at least two outlet-groups each comprising at least one outlet (10 or 11 or 12). A two-stroke engine characterized by: 3. The two-stroke engine according to claim 1, wherein the outlet comprises three outlets each comprising at least one outlet (10 or 11 or 12).
A two-stroke engine characterized by having a group. 4. The two-stroke engine according to claim 1, wherein the partial opening time (T ₁₀ ) of the at least one exhaust port ( ₁₀ ) is at least partially, preferably completely, supplied. The exhaust gas partial flow (V ₁₀ ) which corresponds to the range (Te) between the opening and closing control of the vent-slit device (4) and which belongs to the at least one outlet (10). , 2-stroke engine, wherein at least one turbine (5a, 28) is drivable belonging to exhaust gas partial flow (V _10). 5. A two-stroke engine, characterized in that an exhaust gas turbocharger (5) belonging to the exhaust gas partial stream (V ₁₀ ) belongs. 6. The two-stroke engine according to claim 4, wherein at least one power turbine (28), preferably a turbine (5a) of an exhaust gas turbocharger (5), is added to the exhaust gas partial stream (V ₁₀ ). A) two-stroke engine, characterized by a power turbine (28) arranged in fluid motion parallel to the power turbine (28). 7. The two-stroke engine according to claim 1, wherein the partial opening time (T ₁₁ ) of the at least one exhaust port ( ₁₁ ) is at least partially, preferably completely, supplied. air outlet - slit device (4) of which matches the range of the previous opening control, and belongs exhaust gas partial flow by (V _11), at least one affiliation of the turbine (6a, 29)
A two-stroke engine characterized in that it can be driven. 8. The two-stroke engine according to claim 7, wherein an exhaust gas turbocharger (6) belongs to the exhaust gas partial flow (V ₁₁ ). 9. The two-stroke engine according to claim 7, wherein at least one power turbine (29) is provided in the exhaust gas partial stream (V ₁₁ ).
A two-stroke engine, comprising a power turbine (29) arranged in fluid motion parallel to the turbine (6a). 10. The two-stroke engine according to claim 1, wherein the partial opening time (T ₁₂ ) of the at least one exhaust port ( ₁₂ ) is at least partially, preferably completely, supplied. The range after the closing control of the vent-slit device (4) is matched, and the associated exhaust gas partial flow (V ₁₂ ) can be supplied directly or indirectly to the intake-slit device (4). A two-stroke engine characterized by: 11. The two-stroke engine according to claim 10, wherein a blower (30) is assigned to the exhaust gas partial stream (V12). 12. The two-stroke engine according to claim 11, wherein a cooler (31) belongs to the blower (30). 13. The method according to claim 10, wherein
In cycle engine air supply port - conduit belonging to the exhaust gas partial flow to be supplied to the slit device _{(4) (V 12) (} 2
6) A two-stroke engine, wherein a purifying device (27) is disposed in the engine. 14. The two-stroke engine according to claim 1, wherein each exhaust-group has a unique exhaust manifold pipe (1) extending over the entire cylinder (1).
9, 20 and 21). 15. The two-stroke engine according to claim 1, wherein a catalyst device is assigned to at least the first exhaust gas partial stream (V ₁₁ ).
Cycle agency. 16. The two-stroke engine according to claim 1, wherein at least one catalyst device belongs to each of the uncirculated exhaust gas partial flows (V ₁₁ , V ₁₀ ). A two-cycle institution. 17. The two-stroke engine according to claim 15, wherein the catalyst device is integrated into the associated exhaust manifold pipe (19, 20).
Cycle agency. 18. A two-stroke engine according to claim 1, further comprising a common supercharged air accumulator (8) extending over all cylinders (1). A common supercharger (7) is arranged in front of the at least one supercharger provided by at least one exhaust turbocharger (5, 6). A two-stroke engine, characterized in that it can also be loaded by an exhaust gas partial flow (V ₁₂ ), which can advantageously be supplied to the inlet-slit device (4).