JP2006029327A - Diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high safety and reliability of a 2-cycle diesel engine having a plurality of cylinders, and save the consumption of starting air. <P>SOLUTION: This diesel engine comprises a combustion air intake device 7, and a single actuation chamber 3 provided with an exhaust gas discharge device 10, a fuel injection device 8, and a starting air intake device 13, composed in such a way that a starting operation mode is changeable to an injection operation mode by a changing device 22 that is actuated when a changing speed is reached after engine start. The exhaust gas discharge device is released longer in the starting operation mode than in the injection operation mode. The changing device changes the cylinder 1 from the starting operation mode into the injection operation mode with phase deflection depending on the crank angle of a crankshaft 4 allotted to a piston 2 in it. In this case, changing of the cylinder is conducted every time before the piston passes a closing position to the exhaust gas discharge device in the injection operation mode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a diesel engine, in particular a two-cycle diesel engine having a plurality of cylinders operating out of phase according to a predetermined firing sequence, each cylinder defined by a piston cooperating with a crankshaft and It has a working chamber equipped with an air intake device, an exhaust gas discharge device, a fuel injection device, and a start air intake device. It is possible to switch from the start mode to the injection mode, in which at least some of the cylinders are operated by the start air in each operating cycle, and in the injection mode all the cylinders The operating stroke performed by the combustion of fuel in the operating cycle Related to a two-cycle diesel engine.

  In known engines of this type, the opening and closing times of the exhaust gas exhaust device are the same in both modes of operation. For this reason, compression also occurs in the start-up mode, which is due to the expansion of the start-up air and to the mass moment of inertia of the mechanism that is moved when switching from start-up mode to injection mode. Acts in the opposite direction. When the predetermined switching speed of the crankshaft is achieved in the starting operation mode, all cylinders are conventionally switched from the starting operation mode to the injection operation mode at the same time. Nevertheless, due to the inevitable dead time of the mechanisms involved in the switching process, the actual switching of the individual mechanisms takes place with a corresponding delay with respect to the operation of the switching device, ie with respect to the switching command. This may result in fuel injection not occurring in the switching operating cycle in some situations. In the past, the rotational speed could be reduced due to the braking action of compression, which could result in no more orderly ignition and combustion. For this reason, there is a risk of false start, which can cause an accident, especially in the case of a ship operating process in a harbor or the like. Furthermore, there is a risk of leading to an explosion in the exhaust gas conduit. In order to prevent such drawbacks, a high switching speed must be provided. This still results in a large start-up air consumption, which results in a large start-up air reservoir with a large attached compressor, which necessitates a large construction space, which is insufficient on a ship. The start-up air consumption can be further increased by the dead time of the start-up air intake valve. It is therefore clear that the known design is not simple, is neither compact nor secure and is not sufficiently reliable.

  Therefore, the object of the present invention is to improve the diesel engine of the type mentioned at the beginning in a simple and inexpensive way so that high safety and reliability as well as savings in starting air consumption are achieved. .

  This problem depends on the invention in that the exhaust gas discharge device is opened longer in the start-up mode than in the injection mode, and the switching device depends on the crank angle of the crankshaft assigned to each of the pistons of the cylinder. The phase is shifted from the start operation mode to the injection operation mode, and in this case, the cylinder is changed each time before the piston passes the position where the exhaust gas discharge device is closed in the injection operation mode. Is done.

  This measure ensures that the compression process can be disturbed during the start-up mode. Nevertheless, each cylinder can still carry out one complete compression stroke after switching from its starting mode of operation to the injection mode of operation, so that the subsequent first injection is also ignited and burned, and thereby It is certain that the actual energy supply will result. At the time of the switching device operation, the cylinder is still not able to carry out one complete compression stroke during the operating cycle starting at this time, and thus has already passed the position where the exhaust gas discharge device is closed in the injection mode of operation. It is switched for the first time in the next operating cycle, so that starting air can be obtained again at that time. Therefore, the measure according to the invention is that combustion already occurs in some cylinders, but the other cylinders are still filled with starting air, which causes a high energy supply during the switching process and prevents a reduction in the rotational speed. Return to the switching mode. The switching process can thus be started in an advantageous manner at a relatively low switching speed, which has a favorable effect on the start-up air consumption. Therefore, a relatively small starting air reservoir is sufficient in an advantageous manner. The same is true for the compressor attached to it. Nevertheless, the measure according to the invention guarantees a very stable starting behavior and therefore erroneous starting is reliably avoided. The measure according to the invention thus completely avoids the first-mentioned drawbacks of known designs.

  Advantageous embodiments of the above measures and developments suitable for the purpose are described in the dependent claims. Thus, the cylinders can be individually switched from the starting operation mode to the injection operation mode in order to achieve a particularly high reliability of the switching device.

  Advantageously, the switching device can be configured such that the switching of the cylinder to be switched takes place only after its piston has passed the position where injection has ended in the injection mode of operation. This ensures that erroneous injection is avoided.

  In switching the cylinder from start-up mode to injection mode in the piston angle range between opening and closing of the start-up air intake, the start-up air intake remains open to the specified closed position in that start-up mode , Yet another measure that suits the purpose holds. This ensures that the starting air energy is utilized as much as possible.

  In a particularly preferred embodiment of the above measures, cylinders that have not yet passed through the position where the exhaust gas discharge device is closed in the injection mode of operation when the piston is operating during the operating cycle during which the switching device is operating. Are switched during this operating cycle, and the other cylinders are switched during each subsequent cycle. This reduces the switching process to fewer operating cycles, usually two operating cycles.

  It is advantageous for the exhaust gas discharge device to be closed first in front of top dead center in the start-up mode. This also avoids light compression. Advantageously, the exhaust gas exhaust device can be opened even more slowly in start-up mode than in injection mode. This increases the operating stroke of the starting air in an advantageous manner.

  In yet another advantageous measure, the distance between the position where the start-up air intake device is closed and the position where the exhaust gas discharge device is opened is such that the start-up air taken into the working chamber enters the working chamber before compression. Selected to be able to expand to the pressure of the incoming air. This ensures that the starting air energy is not lost. In this connection, it is likewise advantageous if the exhaust gas discharge device is closed in the start-up mode before the start-up air intake device is opened.

  In yet another development of the invention, an electronically controlled engine is planned. This is a simple method that allows the realization of freely selectable controls independent of the mechanical drive of the mechanism of the injection device, the exhaust gas discharge device and the start-up air intake device, and thus at the time of their start of use. The end point can be moved according to the desire of the present invention. Moreover, this measure has the advantage that the dead time of the controllable mechanism is eliminated in a simple way.

  Further advantageous embodiments of the above measures and developments suitable for the purpose are described in the remaining dependent claims and can be extracted in more detail from the description of the examples below with reference to the drawings.

  The main field of application of the present invention is the two-cycle large diesel engine, for example as it finds application in ship drive systems. The basic structure and mode of operation of this type of engine are well known.

  The two-cycle large diesel engine shown in FIG. 1 comprises a plurality of, in this case four, cylinders 1 arranged in a row, each cylinder 1 having a working chamber 3 defined by a vertically moving piston 2. . Each piston 2 cooperates with the crankshaft 4 through a power transmission device. The power transmission device is depicted here as a connecting rod joint 5. Nevertheless, in large diesel engines, the power transmission device actually includes a crosshead not shown in detail here, which crosshead is connected to the belonging piston through a piston rod and cooperates with the crankshaft through a connecting rod joint. Work.

  The crankshaft 4 is coupled directly or indirectly to the driven unit. In the illustrated embodiment, the crankshaft 4 is directly connected to the propeller 6 of the ship. This can be formed as a propeller with fixed vanes as shown in FIG. 1 as a fixed propeller.

  In normal operation, the working chamber 3 of the cylinder 1 is supplied with the air necessary for combustion taken out from the surroundings, that is, the combustion air, and the combustion air is ignited through the piston 2 to which the combustion air belongs, respectively. Compressed as much as possible. As a result of the subsequent combustion of the fuel, the piston 2 moves downward. After combustion, the exhaust gas produced at this time is released.

  Therefore, in each operation cycle, the compression stroke of the piston 2, the fuel injection, the operation stroke of the piston 2, the exhaust process and the filling process are performed. This operation mode is hereinafter referred to as an injection operation mode.

  Each cylinder here has a combustion air intake device in the form of an air intake slit 7 which is arranged in the lower cylinder region and can be controlled by the respective piston 2 through which the combustion chamber 3 belongs to which it belongs. Air is supplied or filled. In order to inject fuel, each cylinder 1 has at least one fuel injection device, which here takes the form of an injection nozzle 8 connected to a fuel supply pipe 9. Furthermore, each cylinder 1 is equipped with one exhaust gas discharge device, which here takes the form of at least one discharge valve belonging to the exhaust gas outlet 11 exiting the working chamber 3, to which an exhaust conduit 12 is connected. ing.

  In order to start or start the engine, all or selected cylinders 1 are charged with starting air during the downward movement of the piston 2 to which they belong respectively. In this case, the compressed air prepared in the starting air reservoir not shown in detail here is important, and this starting air reservoir is fitted with a compressor which is also not shown in detail. With the aid of this compressor, the start-up air reservoir is filled with air in normal operation. By convention, the starting reservoir is sized so that at least 12 startings can be performed. In the case of starting, in each operating cycle, the operating process performed first by the compressed starting air is performed, and then the exhaust process is performed. Hereinafter, this operation mode is referred to as a start operation mode.

  In order to introduce start-up air, each cylinder 1 is provided with a start-up air intake device. Here, the intake valve 13 for controlling the intake opening provided in advance in the upper cylinder region is important, and the intake opening is connected through a connecting pipe to a starting reservoir which is not shown in detail here.

  Each discharge valve 10 is provided with a drive device 15 in the form of a hydraulic cylinder, for example, which can be controlled by a mechanism that operates electrically or electronically. Similarly, a mechanism that operates electrically or electronically is attached to the injection valve 8 and the start air intake valve 13. This electrically or electronically operated mechanism can here be controlled by the associated electronic controller 16, as suggested through the signal lines 17, 18, 19 coming out of it. A sensor 20 that scans the angular position of the crankshaft 4 is attached to the control device 16. In order to process the sensor signal, the control device 16 includes a computer 21, which is connected to the sensor 20 through a signal line 24.

  However, the engine as a whole is configured as an electrically controllable engine with a central computer that cooperates with a sensor 20 that scans the angular position of the crankshaft 4 to electrically control any electronically controllable mechanism. You can also In any case, the electronics do not require the mechanical operation drive of the mechanism described above and can be controlled independently of each other, ensuring a simple method that allows displacement of the control points. Make things. This also in this case controls the mechanism to be controlled, here at least the exhaust gas discharge device, the fuel injection device, and the start-up air intake device by the advance corresponding to the dead time of these mechanisms and thus for switching. This is possible in a simple manner that the desired crank angle is achieved. The crankshaft movement of the switching point that occurs throughout the dead time depends on the speed, but can still be easily grasped by calculation.

  A switching device 22 is connected to the engine, and switching from the starting operation mode to the injection operation mode is performed through the switching device 22 when the engine is started. The switching device 22 is attached to the electronic control device 16, i.e. included therein. The switching device 22 is actuated as soon as the crankshaft 4 reaches a predetermined rotational speed during the starting process. The operating command can be given automatically with the help of the calculator 21. The initial start command can also be activated manually as suggested through the input device 23.

  The injection operation mode corresponding to the normal operation and the start operation mode applied only to the engine start can be clearly seen from FIGS. In this case, the rotational motion carried out by each crankshaft 4 is suggested as a crank angle circle. In the case of a two-cycle engine, the operating cycle includes the upward and downward movement of the piston 2 and the accompanying rotation of the crankshaft 4 over 360 °. Therefore, each point of the crank angle circle corresponds to a corresponding position of the piston 2 in an operating cycle that includes one up and down movement of the piston 2. The top dead center is indicated by OT each time, and the bottom dead center is indicated by UT each time.

  In the injection mode, the discharge valve 10 is opened in the crank angle range before the UT and closed in the crank angle range after the UT. The opening time point before the UT is indicated by position 30 in FIG. 2 and the closing time point after the UT is indicated by position 31. The angular spacing between positions 30 and 31 is about 60 ° in the illustrated example. However, it is natural that there is a deviation from this depending on the structural style. Fuel injection occurs in the top dead center region. This can be started slightly before the OT to suit the purpose and ends up somewhat after the OT. The start of injection is indicated by position 32 in FIG. The spacing between positions 32 and 33 is about 30 ° in the illustrated example. Of course, there can be deviations here as well.

  In the start-up mode, the exhaust gas outlet opening 11 is more than in the injection mode to ensure that no compression occurs during the upward stroke of piston 2, and therefore no force acts on piston 2 in the opposite direction. Is also essentially open for a long time. Therefore, as is clear from FIG. 3, the closing time point of the discharge valve 10 is moved from the position 31 in FIG. 2 to the position 31a slightly before the OT. The position 30 for opening the discharge valve 10 can remain unchanged or can be even closer to the UT. The fuel injector is in a non-operating state in the starting mode of operation, i.e. switched off.

  In order to carry out the rotation of the crankshaft 4, the working chamber 3 of all or selected cylinders 1 is filled with starting air. For this purpose, the respective start-up air intake devices to which they belong operate correspondingly. Intake valve 13 belonging to the start-up air intake device opens according to FIG. 3 in the region of top dead center, preferably slightly before OT. The opening time is indicated by position 35 in FIG. In any case, the intake valve 13 is first opened and then the discharge valve 10 is closed. Therefore, the position 35 is arranged after the position 31a in the rotation direction. The intake valve 13 is closed at position 36, which is far behind the OT, but is located in front of the position 30 where the discharge valve 10 opens, as viewed in the direction of rotation.

  The distance between the position 36 where the start-up air intake device 13 closes and the position 30 where the exhaust gas discharge device 10 opens is the air where the start-up air supplied into the working chamber 3 enters the working chamber 3 before compression It is suitable for the purpose to be able to expand to a pressure of. This allows full utilization of the start-up air energy. Moreover, in order to extend the operating stroke carried out by the start-up air, the position 30 where the discharge valve 10 opens is set to the injection operation so that the discharge valve 10 opens later in the start-up mode than in the injection mode. It can be moved further in the direction of UT.

  In the case of a transition from the start-up operation mode introduced as already mentioned above to the injection operation mode, if the predetermined speed of the crankshaft 4 is reached in the start-up operation mode, all according to the invention The cylinders 1 are not switched at the same time, but depending on the position of the piston, that is, the phase is shifted depending on the crank angle of the crankshaft 4 belonging to each piston 2, more strictly speaking, one Alternatively, the plurality of cylinders 1, i.e. one or more pistons 2, still have the possibility of performing a complete compression stroke within the operating cycle involving the operation of the switching device 22, i.e. the discharge valve 10 The phase 31 is shifted so that it does not yet exceed the closing position 31 in the injection mode of operation and is switched in an operating cycle that includes the operation of the switching device 22. The other cylinder 1 is first switched in the next operating cycle, thus first still obtaining start-up air. The switching of the cylinder phase shift can be performed for each group or preferably individually.

  This results in a switching mode in which many cylinders 1 are still filled with start-up air and the other cylinders already get fuel injection that leads to ignition and combustion. Thus, the energy intake into the engine during switching in this manner is optimized, which results in a very stable switching condition and avoids false starting. Here, the switching can already be carried out at a relatively low speed, which saves start-up air and thus requires less start-up air. Overall, the measure according to the invention of the space-saving construction of the start-up air supply is very beneficial. High energy carryover during the switching process has proven particularly advantageous when relatively heavy loads are applied to the engine, such as in the illustrated embodiment in the form of a stationary propeller 6.

  In order to make full use of the start-up air, this cylinder is used in the start-up mode when the cylinder 1 is switched from start-up mode to injection mode in the crank angle range between opening and closing of the start-up air intake 13. It can be planned to remain open to its prescribed closed position 36. However, it can be considered that the switching of the cylinder 1 is first caused when the corresponding piston 2 has already passed the position where the intake valve 13 is closed in the starting operation mode. In any case, first, in any case, when the corresponding piston 2 passes the position 33 where the injection ends in the injection operation mode, the switching device 22 is switched during an operation cycle in order to avoid erroneous fuel injection. Switching of one or more cylinders 1 occurs.

  It is suitable for the purpose that the switching device 22 is configured as a program stored in a computing device, here a computer. Therefore, adaptation to the circumstances of the individual case can be carried out using the software in an advantageous manner.

  The number of cylinders 1 that are charged with starting air when the engine is started can be determined according to the expected load. Furthermore, the corresponding program can be stored in the computer 21 here. In this case, the cylinders 1 that are not involved operate together empty. Nevertheless, all cylinders 1 are involved in switching to the injection mode. At this time, when the cylinder 1 first obtains fuel, that is, when the piston 2 of the corresponding cylinder 1 has the possibility of performing a complete compression stroke between the operation of the switching device 22 and the injection, the injection nozzle 8 It is valid in each case that is first put into operation.

1 is a schematic view of a diesel engine according to the present invention. FIG. 2 shows the cylinder according to FIG. 1 with a cycle of injection mode of operation. FIG. 2 shows a cylinder arranged according to FIG. 1 with a cycle of start-up mode.

Explanation of symbols

1 cylinder
2 piston
3 Working chamber
4 Crankshaft
5 Connecting rod joint
6 Ship propeller
7 Slit
8 Injection nozzle
9 Fuel supply pipe
10 Discharge valve
11 Exhaust gas outlet
13 Start-up air intake valve
15 Drive unit
16 Control unit
17,18,19 Signal line
20 sensors
21 Calculator
22 Switching device
23 Input device
24 signal lines
Open point position before 30 UT
Closing point position after 31 UT
Position just before 31a OT
32 Injection start position
33 Injection end position
35 Position at release
36 Closed position
OT top dead center
UT bottom dead center

Claims (21)

In a diesel engine, in particular a two-cycle diesel engine having a plurality of cylinders (1) operating out of phase according to a predetermined ignition sequence,
Each of the cylinders (1) is defined by a piston (2) that cooperates with the crankshaft (4), and includes a combustion air intake device (7), an exhaust gas discharge device (10), and a fuel injection device (8), It has a working chamber (3) equipped with a starting air intake device (13), and when starting the engine, the switching device (22) that can be operated when the switching speed is reached is switched from the starting operation mode to the injection operation mode. In the starting operation mode, at least part of the cylinder (1) is operated by the starting air in each operating cycle, and in the injection operating mode, each cylinder (1) is operated in each operation mode. A diesel engine in which an operating stroke performed by combustion of fuel in a cycle is performed,
The exhaust gas discharge device (10) is opened longer in the start-up mode than in the injection mode, and the switching device (22) has a crankshaft (4) assigned to the cylinder (1) and its piston (2), respectively. ) Is shifted from the start operation mode to the injection operation mode by shifting the phase depending on the crank angle, and each time the cylinder (1) is switched, the piston (2) is connected to the exhaust gas discharge device (10) in the injection operation mode. A diesel engine characterized in that the diesel engine is performed before passing the position where the engine is closed.   2. The diesel engine according to claim 1, wherein the switching device (22) individually switches the cylinder (1) from the start operation mode to the injection operation mode.   Switching from the start operation mode to the injection operation mode is performed each time after the piston (2) of the corresponding cylinder (1) passes through the position (33) where the injection has ended in the injection operation mode. Item 3. The diesel engine according to Item 1 or Item 2.   In switching the cylinder (1) from start-up mode to injection mode in the piston angle range between opening and closing of the start-up air intake device (13), the start-up air intake device is in the specified closed position ( The diesel engine according to any one of claims 1 to 3, wherein the diesel engine remains open until 36).   Switching from the start operation mode to the injection operation mode is performed each time after the piston (2) of the corresponding cylinder (1) passes through the position (36) where the start air intake device (13) is closed in the start operation mode. The diesel engine according to any one of claims 1 to 3, wherein   During the operation cycle in which the switching device (22) is operated, when the switching device (22) is operated, the piston (2) has not yet passed the position where the exhaust gas discharge device (10) is closed in the injection mode. The non-cylinders (1) are switched during an operating cycle in which the switching device (22) is operated, and the other cylinders (1) are switched during each subsequent cycle. 6. The diesel engine according to any one of claims 5.   The closed position (31a) of the exhaust gas discharge device (10) is slightly ahead of top dead center in the crank angle range in the starting operation mode, according to any one of claims 1 to 6. The listed diesel engine.   8. The diesel engine according to claim 1, wherein the exhaust gas discharge device (10) is opened later in the starting operation mode than in the injection operation mode.   9.Starting air intake device (13) opens at the piston position in the region of top dead center, preferably just before top dead center (position 35). The diesel engine according to one item.   10. Diesel engine according to any one of the preceding claims, characterized in that the starting air intake device (13) closes (position 36) before the exhaust gas discharge device (10) opens (position 30). .   The distance between the position (36) where the start air intake device (13) is closed and the position (30) where the exhaust gas discharge device (10) is opened is the distance between the start air taken into the working chamber (3) 11. Diesel engine according to claim 10, characterized in that it is selected to be able to expand to the pressure of the air that has previously entered the working chamber (3).   12. The exhaust gas discharge device (10) according to any one of claims 1 to 11, wherein the exhaust gas discharge device (10) is closed (31a) before the exhaust gas discharge device (10) is opened (position 35) in the starting operation mode. The listed diesel engine.   The diesel engine according to any one of claims 1 to 12, wherein a sensor (20) for scanning an angular position of the crankshaft (4) is connected to the switching device (22).   A computer (21) for calculating the rotational speed and crank angle of the crankshaft (4) based on a signal from the sensor (20) is connected to the switching device (22). The diesel engine as described in any one of.   15. The diesel engine according to any one of claims 1 to 14, wherein the switching device (22) is configured as a program stored in a computer (21).   At least the exhaust gas discharge device (10), the fuel injection device (8), and the start-up air intake device (13) have individual mechanisms independent of the mechanical drive unit. 15. The diesel engine according to any one of 15.   Electronics that cooperate with the sensor (20), including a computer (21) and a switching device (22) to control at least the injector (8), the exhaust gas exhaust device (10), and the start-up air intake device (13) The diesel engine according to any one of claims 1 to 16, further comprising a control device (16).   18. The diesel engine according to claim 17, wherein the diesel engine is configured as an electronically controllable engine.   Control of at least the controllable mechanisms of the exhaust gas discharge device (10), the injection device (8), and the start-up air intake device (13) is performed by a course corresponding to the dead time of these mechanisms. The diesel engine according to any one of claims 16 to 18.   In the starting operation mode, only a part of the cylinder (1) is subjected to the impact of the starting air, the other cylinders (1) are operated idle, and when the switching device (22) is operated, all cylinders ( 20. The diesel engine according to any one of claims 1 to 19, wherein 1) is switched to an injection operation mode so that injection occurs only when complete compression is performed in advance.   The diesel engine according to any one of claims 1 to 20, wherein the diesel engine is configured as a two-cycle large diesel engine.

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