JP5698292B2 - Internal combustion engine operating method equipped with large reciprocating piston with crosshead and appropriate engine accordingly - Google Patents

Description

  The present invention relates to a method of operating an internal combustion engine equipped with a large reciprocating piston with a crosshead.

Technical background

  The engine (hereinafter referred to as an engine) includes at least one cylinder that surrounds a combustion chamber and is divided by each piston, and is coupled to a rotatable output crankshaft through means having a crosshead function. It has a piston. During the operating period of the engine, combustion takes place in this combustion chamber, in particular with fuel supplied directly to the combustion chamber. This combustion scavenging is performed by introducing pressurized scavenging gas from the second end of the cylinder toward the first end. And at least a part of the combustion products generated by the combustion action in the combustion chamber is used for recirculation in order to reduce NOx-containing substances in the exhaust gas that is subsequently released from the engine to the atmosphere. The At the first end of the cylinder, exhaust gas is discharged from the combustion chamber through the opening of the exhaust port, and recirculated gas is discharged from the opening of the recirculation gas discharge port.

  An engine of the kind described above is described in DE 10 2005 057 207 A1 (Patent Document 1), which describes the opening stage of the recirculation gas outlet before the start of the outlet opening stage. Is described as starting. This is because undiluted combustion gas needs to be secured for recirculation. However, since this combustion gas is very hot and pressurized, the recirculation gas outlet control valve through which this high-temperature and pressurized combustion gas passes is subjected to severe thermal stress. In order to solve this problem, DE 10 2005 057 207 A1 patent publication discloses two recirculation gas valves that operate alternately as exhaust valves through which combustion gas passes and as intake valves through which recirculation gas passes. Has proposed. However, the arrangement of two such valves is very complicated and expensive.

  Also, US 2004/0103863 A1 describes another engine of the same type as described above, in which the recirculation gas outlet performs several opening operations during each operating cycle of the engine. ing. In this engine, the first opening operation of the recirculation gas outlet is started simultaneously with the opening operation of the exhaust port, and the last opening operation is already completed before the exhaust port is closed. . Accordingly, the valve for controlling the recirculation gas discharge port operates at the stage of the operation cycle held for discharging the high-temperature exhaust gas. For this reason, the valve controlling the recirculation gas outlet is in contact with the hot exhaust gas during each opening stage of the valve, and the thermal stress of the valve may not be reduced properly due to the opening operation more than once. Concerned.

  Another engine of the same kind as described above is known from Japanese Patent JP 3213616A (Patent Document 3). In this patent, the recirculation gas outlet is opened with a slight overlap period following the opening stage of the outlet. Therefore, since the recycle gas contains only a small amount of combustion products, the NOx reduction effect is very small.

German Patent Application Publication No. 10 2005 057 207 Specification US Patent Application Publication No. 2004/0103863 JP-A-3-213616

  The object of the present invention, starting from the prior art described above, is not only that a suitable amount of combustion products can be recirculated, but also that proper cooling of the combustion gas valve is ensured and nevertheless manufactured. It is to improve the engine and the operating method of the engine having a two-stroke reciprocating piston with combustion gas recirculation function so that the costs can be made relatively low.

  The object of the invention is achieved by a method combining the features of claim 1 and an engine by the feature combination of claim 10.

  The gist of the present invention is to open the exhaust port and operate the designated valve several times during the engine operation cycle, and allow the gas to pass for each operation. The first opening stage of the exhaust port, which is performed every operation of the specified valve in one operation cycle, is started at least before the start of the scavenging operation of the combustion chamber, and is performed every operation of the specified valve. The final opening stage of the exhaust is performed after the basic scavenging of the combustion chamber is complete.

  The first opening phase of the recirculation gas valve is carried out early in the operation process, so that a very beneficial recirculation is used to properly reduce the NOx content of the exhaust gas that is subsequently released into the atmosphere. For this purpose, it is beneficial to obtain undiluted combustion gas during this first opening phase. However, there is an adverse effect due to the high-temperature gas during the original function execution period of the recirculation gas valve, but this adverse effect is advantageously improved by further introducing the opening stage of the recirculation gas valve. This is because the further introduced opening stage occurs while a relatively low scavenging gas temperature is present in the combustion chamber and is heated by the moderately pressurized gas stream entering the recirculation gas valve. This is because the stressed recirculation valve will result in better cooling, and the thermal stress will be much smaller since the next thermal effect will occur in the next cycle of operation before the next occurrence. This is because the valve functions safely, and therefore the life of the valve is extended. Furthermore, an advantage of the present invention is that a single recirculation gas valve is sufficient, and such a plurality of valves per cylinder is completely unnecessary, allowing for simple and low cost production. .

1 is a schematic view of an internal combustion engine having a large reciprocating piston with a crosshead according to the present invention. It is a diagram which shows the relationship between the opening area at the time of gas passage, and cylinder pressure with respect to the crank angle after an upper dead center.

  Hereinafter, exemplary operations of the present invention will be described in detail with reference to the accompanying drawings.

  Further useful examples with beneficial development and higher ideas are detailed in the subclaims.

  Thus, it has been confirmed in the past that the recirculation gas valve may be beneficial with respect to the final opening phase during the time period during which the piston is going up. This time period occurs as soon as possible after the exhaust valve is closed, which is beneficial. As a result, the scavenging gas that is at its lowest temperature and lowest pressure and therefore in its leanest state leaves the combustion chamber at the time before many operations are performed by compression heating by the piston during the upward stroke of the piston. This scavenging gas cools around the recirculation gas valve. Such a final opening stage preferably occurs in the vicinity of a crank angle of 250 to 280 degrees after the top dead center.

  The main field in which the present invention is used is as a one-way scavenging two-stroke diesel engine and / or gas engine used for ship propulsion and / or power plant operation. In the field of internal combustion engines with large reciprocating pistons with crossheads.

  The engine shown in FIG. 1 is usually provided with a crankcase 1 in which several rows of cylinders 2 are arranged, but at least one cylinder 2 is arranged. Each cylinder 2 includes a reciprocating piston 3 that operates as a moving section of the combustion chamber 4. The piston 3 is linked to a crankshaft 5 disposed in the crankcase 1 by a piston rod 6, a crosshead 7 and a connecting rod 8. A scavenging port 9 is arranged as an elongated gap below the cylinder 2 (located at the second end). The scavenging port 9 is controlled by the piston 3 through which the piston 3 can pass. In the region of the scavenging port 9, each cylinder 2 is surrounded by a scavenging gas passage 10, which is connected to a common scavenging gas receiver 11 by a scavenging gas line 12. One-way scavenging of the combustion chamber 4 occurs during the operation of the piston 3 by introducing pressurized scavenging gas from the second end of the cylinder toward the opposite upper end (first end). Followed by combustion, producing combustion gases. This combustion is usually generated by fuel supplied by a fuel injection means (not shown) for injection into the combustion chamber. This fuel supply, usually performed in the form of injection, is performed as a series of operations. However, as a pilot injection for ignition, it is also possible to introduce a part of the fuel at an early stage and then perform the main injection. When combustible gas is used for engine operation, main injection is possible even by pilot injection for ignition of this combustible gas. Usually, the fuel is introduced directly into the combustion chamber 4. However, when a combustion chamber having a pre-combustion chamber is arranged, it is possible to introduce a part of fuel at an early stage as pilot injection into the pre-combustion chamber.

  In the upper part of the cylinder 2, an exhaust port controlled by an assigned exhaust valve 14 is provided together with a recirculation gas outlet 15 controlled by an assigned recirculation gas valve 16. Exhaust valve 14 and recirculation gas valve 16 are operated by assigned independent actuators that are controlled according to engine running parameters. The exhaust port 13 of each cylinder 2 is connected by a bent tube 17 to an exhaust receiver 18 common to one or more all engine cylinders. Exhaust gas collected in the exhaust receiver 18 is guided to a turbocharger 19, and the turbocharger 19 receives air via an air conduit 20 including a turbine driven by exhaust gas and an air cooler 21. And a compressor that supplies the scavenging gas receiver 11. Although not shown, devices for gas processing and / or energy utilization may be inserted and installed at various locations in the flow path shown in FIG.

  The exhaust gas passing through the turbocharger turbine is here released directly into the surrounding area. It is desirable that the exhaust gas to be released has a low NOx content. In order to achieve this object, the combustion gas generated by the combustion in the combustion chamber 4 is partially recirculated. For this purpose, the recirculation gas outlet 15 is connected to a recirculation conduit 22. In the scavenging conduit 20, etc., this recirculation conduit 22 can enter any function of the scavenging gas system, such as the scavenging gas receiver 11 in the example of operation shown in FIG. The recirculation conduit 22 is connected to a recirculation gas receiver 23, which is supplied with recirculation gas by a line 24 connected to the recirculation gas outlet 15 of the cylinder 2. In this example, a control valve 26 for controlling the flow rate is disposed downstream of the recirculation gas receiver 23. Here, a recirculation gas processing device 25 is provided downstream of the control valve 26, and this device includes, for example, a gas cleaning device, a cooler, and a water fog collector.

  The flow path described in FIG. 1 is a purely illustrative system, consisting of several typical components and the general flow paths required for exhaust and scavenging gas. Of course, some processing equipment may be omitted, and the internal flow path downstream of the compressor and upstream of the turbine may include other suitable processing equipment. Within the scope of the claims, processing devices other than this system may also be provided upstream of the compressor and / or downstream of the turbine. Further, the recirculation conduit 22 may be connected to the scavenging flow path at any point between the scavenging port and the compressor. Of course, you may provide the functional apparatus other than the above-mentioned.

  2, the graph 30 shows the opening area of the scavenging port 9 toward the combustion chamber 4, the graph 31 shows the opening area of the exhaust port 13, and the graphs 32a and 32b show the opening area of the recirculation gas discharge port 15. Is shown. The graph 33 represents the cylinder pressure, that is, the pressure in the combustion chamber 4. The horizontal axis shows the rotational position of the crankshaft 5 at a single operating cycle, the rotational position of the crankshaft 5 in the range of the crank angle from 100 degrees to 300 degrees, the position of 180 degrees corresponding to the bottom dead center (BDC), The positions of 0 degrees and 360 degrees (outside the horizontal axis) corresponding to the top dead center (TDC) are shown.

  As can be seen from FIG. 2, the scavenging port 9 shown by the graph 30 and the exhaust port 13 shown by the graph 31 are opened only once during the period of one operation cycle. In contrast, the recirculation gas outlet 15 is opened several times during a single operation cycle, as shown by the two graphs 32a, 32b. Therefore, the actuator for the recirculation gas valve 16 is controlled so that the valve 16 opens corresponding to the graphs 32a and 32b. Usually, two opening stages 32a, 32b are provided. The first opening stage is aimed at collecting undiluted combustion products for recirculation. The last (second) opening stage is aimed at cooling the recirculation gas valve 16 and the surrounding environment.

  Accordingly, the first opening stage (graph 32a) of the recirculation gas discharge port 15 is started at the same time as the opening operation of the exhaust port 13 at the latest, and is substantially completed at the start of the scavenging of the combustion chamber. Is preferred. In the example of FIG. 2, the opening stage of the scavenging port 9 has a crank angle between 140 ° and 220 ° after passing through the top dead center, and this angle is in the range of 40 ° symmetrically around the bottom dead center. is there. Further, in the opening stage of the exhaust port 13, the crank angle after passing through the top dead center is in a range of 120 degrees to 240 degrees, and this angle is in a symmetrical 60 degrees range before and after the bottom dead center. The case where the above two angular intervals are symmetrical with respect to the bottom dead center has been described. However, in the engine of the present invention, the intermediate value (bottom dead center) only needs to be included. As a result, these angular intervals may be located asymmetrically around bottom dead center. The first opening stage (graph 32a) of the recirculation gas valve 16 is started around the crank angle of 5 degrees before the opening stage of the exhaust port 13 starts. The recirculation gas valve 16 is almost completely closed while the scavenging port 9 is slightly opened in this interference region, so that it overlaps with the start of the opening of the valve by a crank angle of about 10 degrees. The low pressure, low temperature scavenging gas does not pose a significant risk of diluting the collected recycle gas.

  As described above, the graph 33 corresponds to the pressure in the combustion chamber 4. This pressure decreases with the opening of the exhaust port 13, and during the opening period of the scavenging port 9, the pressure in the combustion chamber 4 is the same as the pressure of the scavenging system. After closing the scavenging port 9 and the exhaust port 13 generated in the example shown in FIG. 2 near the crank angles of 220 degrees and 240 degrees after passing through the top dead center, the pressure in the combustion chamber 4 increases as the piston 3 rises. It rises according to the process. As a result, as indicated by 33a, the pressure in the combustion chamber 4 increases slowly, but gradually increases as indicated by 33b at the right end of the graph 33.

  The second opening stage of the recirculation gas outlet 15 (graph 32b) must be completed before the pressure in the combustion chamber 4 begins to gradually increase as described above. On the other hand, the second opening stage must be started after the scavenging port 9 and the exhaust port 13 are closed. In the example shown in FIG. 2, the second opening stage of the recirculation gas outlet 15 occurs at a crank angle of 250 degrees to 280 degrees after passing through the top dead center, as shown in the graph 32b. The above conditions are achieved. The value of the angle approximates a crank angle of ± 10 degrees. Here, the second opening stage is slightly shorter than the first opening stage.

  If there is no second opening stage of the recirculation gas outlet 15, the pressure in the combustion chamber increases according to the broken line in FIG. As shown at 33c, this second opening action delays this pressure increase somewhat. As can be seen from the curve of 33b, the second opening operation of the graph 32b is a slight decrease in the pressure in the combustion chamber compared to the case where there is no second opening stage (broken line above 33b and 33c). Result. Such a pressure decrease, however, can be easily compensated, for example, by slightly increasing the scavenging system pressure, closing the exhaust valve early, etc. However, the second opening operation of the recirculation gas valve 16 can also be used to control the compression pressure in the combustion chamber 4.

  The curve shown in FIG. 2 is a typical example for a clear explanation. For any particular embodiment of the present invention, the associated engine curves may differ, such as maximum values, curve shapes, and some relative positions with respect to crank angle. Furthermore, the case where the curves 30 and 31 are substantially symmetrical around 180 degrees (ie, bottom dead center) has been described, but this is not relevant to the present invention, but this may be performed by other methods. . The inventive idea here is to exhaust the cooling gas from the combustion chamber 4 through the recirculation gas outlet 15 via the recirculation gas valve 16 during the second opening operation (graph 32b). This pressure is realized by the combustion chamber being closed by the ascending piston.

  In the operation example of FIG. 1, the recirculation gas receiver 23 is filled with the gas discharged from the combustion chamber 4 during the opening stage of the recirculation gas discharge port 15 which is executed twice. In the receiver 23, the receiving gas is mixed, and all the mixed gas is recirculated via the recirculation conduit 22 and introduced into the entire processing apparatus 25. However, by appropriate means, the gas at the first opening stage and the gas at the second opening stage can be diverted to different downstream flow paths, which may be a problem as a special example. is there. Accordingly, the gas at the first opening stage can be introduced into the entire processing apparatus 25, while the gas at the second opening stage bypasses the receiver 23 and the processing apparatus 25 and is separated. It is possible to be led to the circulation path and merge with the gas of the first opening stage downstream of the processing device 25 or at least downstream of the gas scrubber of this device. In other embodiments, there is also the possibility that the gas at the second opening stage is released or used for something else.

  As a means of beneficially realizing the present invention, it can be arranged in a newly produced engine. On the other hand, as a method of providing the invented engine, necessary new means are incorporated into a conventional existing engine not included in any of the claims described below. When incorporating new means into engines that do not have a conventional CGR or EGR system, at least one recirculation gas discharge valve 16 is added by adding an exhaust recirculation conduit to the required theoretical and physical control elements. To the existing cylinder head or to the alternative cylinder head employed is substantially necessary. A new means of retrofitting an engine with an existing CGR valve and CGR flow path to the engine of the present invention is the addition of the necessary theoretical and physical control elements, and at least one recirculation gas discharge valve. 16 is to provide a new delay opening stage (graph 32b).

  For the sake of clarity, the operating cycle and sequence of the cylinders in the claims is the total stroke of two consecutive pistons (down stroke and start) of the cylinder with the exhaust valve 14 starting from the first end at top dead center. The explanation was specified as the ascending process). Of course, the characteristic positions of the first opening timing (graph 32a) and the final opening timing (graph 32b) of the recirculation gas discharge means 15 are the opening operation of the scavenging port 9 and the stroke of the piston. Of course, the operating principle of this engine is as long as it relates to the end of scavenging gas inlet to the first end of the cylinder while going to the first cylinder end as well as to the present invention. The initial claims for both the method and the engine due to the periodic nature of the are extended to include other definitions for the operating cycle of the cylinder.

Claims (14)

An output crankshaft (5) which has at least one cylinder (2) which surrounds the combustion chamber (4) and is divided by each piston (3) and which can be rotated via means (7) having a crosshead function. ) And a piston (3) connected to the combustion chamber (4) during the engine operation cycle, and the second end of the cylinder (2) is moved from the first end to the first end. On the other hand, in the method of operating an internal combustion engine having a large reciprocating piston with a crosshead, in which scavenging after combustion is performed by introducing pressurized scavenging gas,
Recirculating at least a portion of the combustion products generated by combustion in the combustion chamber (4) to reduce the NOx content of the exhaust gas subsequently released into the atmosphere from the engine;
At the first end of the cylinder (2), the exhaust gas passes through the opening of the exhaust port (13), and the recirculated gas passes through the opening of the recirculated gas discharge port (15), thereby opening the combustion chamber (4). And during the operating cycle of the engine, the recirculation gas outlet (15) is opened several times, allowing gas to pass through each opening,
At least before the start of scavenging of the combustion chamber (4), a first opening stage of the recirculation gas outlet (15) is started, during the operation of the piston stroke towards the first end of the cylinder, After the operation of introducing scavenging gas into the combustion chamber (4) at the second end of the cylinder is basically completed, the final opening stage of the recirculation gas outlet (15) is performed. A method for operating an internal combustion engine comprising a large reciprocating piston with a crosshead.  The first opening stage of the recirculation gas discharge port (15) is started at the same time as the opening of the exhaust port (13) at the latest, and when the scavenging of the combustion chamber (4) starts, the first opening stage is basically The operation method according to claim 1, wherein the operation is completed.  The operating method according to claim 1 or 2, characterized in that the second opening stage of the recirculation gas outlet (15) is the last opening stage started after the exhaust opening (13) is closed. .  4. The first opening stage of the recirculation gas outlet (15) starts in a crank angle range of 250 ± 10 degrees after passing through top dead center. The driving | running method as described in a term.  5. The method according to claim 1, wherein the final opening stage of the recirculation gas outlet ends in a crank angle range of 280 ± 10 degrees after passing through the top dead center. Driving method described in 1.  The last opening stage of the recirculation gas outlet (15) is in the range of a crank angle of 240 to 290 degrees after passing through the top dead center. The driving method described.  7. The length of the last opening stage of the recirculation gas outlet (15) is shorter than the length of the first opening stage of the recirculation gas outlet (15). The driving | running method of any one of these.  All the gas passing through the combustion chamber (4) via the recirculation gas outlet (15) in all opening stages in the same cycle is normally recirculated. The operation method according to any one of 1 to 7.  During the first opening phase, the gas passing through the combustion chamber (4) via the recirculation gas outlet (15) is used for exhaust gas recirculation while The gas passing during the opening period is diverted downstream of the recirculation gas outlet (15) and can be used for other applications. Driving method. Having at least one cylinder (2) surrounding the combustion chamber (4) and separated by each piston (3);
Having said piston (3) connected to a rotatable output crankshaft (5) via means (7) having a crosshead function;
At least one combustion gas outlet means (13) and at least one recirculation gas outlet means (15) at the first end of the cylinder (2);
Both means (13, 15) can be controlled independently by the specified valve means (14, 16),
Inhaling scavenging gas towards the first cylinder end and having at least one scavenging port (9) at the second end of the cylinder (2) controlled by the piston (3); Internal combustion engine with a large reciprocating piston with crosshead in which each recirculation valve means (16) designated as recirculation gas outlet means (15) is opened several times during two successive full strokes of the piston In
At least before the scavenging port (9) is opened for scavenging towards the first end of the cylinder, a first opening stage of the recirculation gas outlet (15) is started, the cylinder During the operation of the piston (3) stroke toward the first end of the cylinder and after the operation in which the scavenging gas toward the first end of the cylinder is sucked through the scavenging port (9) is basically completed, An internal combustion engine comprising a large reciprocating piston with a crosshead, characterized in that the final opening stage of the recirculation gas outlet (15) is performed.  Each valve means (16) assigned to the recirculation gas outlet means (15) is opened twice during the whole stroke of two successive pistons, the second and final opening stages being the exhaust valve means. 11. The engine according to claim 10, wherein the engine is executed after the closing of (14).  12. The last opening stage of the recirculation gas valve means (16) is in a range of crank angles of 250 ± 10 degrees and 280 ± 10 degrees after passing through the top dead center. Listed agencies.  The first opening of the designated recirculation gas outlet (15) further comprising one or more exhaust gas recirculation conduits (24, 22) connected to the designated recirculation gas outlet (15) 13. Engine according to any one of claims 10 to 12, characterized in that, in the stage, the exhaust gas recirculation conduit is filled with gas that has passed through the combustion chamber (4). One or more gas treatment and control devices (25, 26) are provided in the exhaust gas recirculation conduit (24, 22), the exhaust gas recirculation conduit being pressurized scavenging gas leading to the scavenging port (9) 14. Engine according to claim 13, characterized in that it is further attached to a working conduit (12, 20).

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