JP2016089825A - Method for controlling rapid reverse rotation in reciprocating piston type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling a reciprocating piston type internal combustion engine in which its reverse rotation can be carried out more efficiently and rapidly in its opposite direction.SOLUTION: An engine has a cylinder in which a piston is arranged to be enabled to reciprocate and move between a top dead center corresponding to a crank angle of 180° and a bottom dead center corresponding to a crank angle of 0° or 360°. The cylinder has an outlet valve that can be hydraulically operated with a prescribed releasing pressure through hydraulic liquid medium, preferably through valve hydraulic pressure from hydraulic oil. In accordance with this invention, fuel supplying to the engine is interrupted at a stage of applying brake and the hydraulic medium is applied by a prescribed maximum releasing pressure of valve hydraulic pressure at the first outlet valve of the first cylinder and under the first crank angle in a region of the top dead center position of the first piston related to the first cylinder, thereby the first outlet valve is automatically released at the second crank angle by the valve hydraulic pressure when the first piston passes through the top dead center position at its most fastest speed.SELECTED DRAWING: None

Description

  The invention relates to a reciprocating piston internal combustion engine, in particular a rapid reversal of rotation in a first direction of rotation of a crankshaft of a low speed uniflow scavenging large two-stroke diesel engine according to the preamble of independent claim 1. Or it relates to a method for controlling braking.

  Large diesel engines are frequently used as a ship drive or in steady state operation, for example in steady state operation for driving large generators for generating electrical energy. In this respect, the engine generally operates in a permanent operation over a long period of time, and thus security and convenience in operation are strongly required. Thus, particularly long service periods, low friction, economical handling of fuel and operating materials are the main criteria for machine operation for the operator. The piston movement behavior of such a large-diameter low-speed diesel engine is a decisive factor, especially for the length of maintenance, convenience and lubricant consumption, and directly the operating cost and even the operating efficiency. .

  In ocean shipping, it is possible to brake the ship from full speed at the shortest possible distance in the event of an emergency or to reverse the engine as quickly as possible so that the propeller rotates in the opposite direction as quickly as possible, There has always been a desire and need to be able to continue operation in the opposite direction as soon as possible. Over the years, various processes for this purpose have been tried for relatively small motor or motorboats, and reversal could often be done simply by a transmission. On the other hand, “emergency braking”, that is, rapid braking of a large vessel equipped with a large reciprocating piston internal combustion engine such as a low-speed uniflow scavenging large two-stroke diesel engine has not been widely used. It is a problem of resolution. This is related to the problem of rapidly reversing the engine from one direction of rotation to the opposite direction of rotation in addition to the braking of the ship, which is closely related to this.

  This is a problem that should not be underestimated, especially for low speed uniflow scavenging large two-stroke diesel engines. This is because this engine is so large and powerful that it is practically impossible to make wise use of the transmission and / or clutch between the engine and the propeller. Therefore, the propeller is fixedly connected to a crankshaft of a large diesel engine of a ship equipped with an engine so as to be rotatable through the shaft.

  Clearly, therefore, the structure of the drive device is substantially simpler than a drive device in which a transmission is provided between the propeller and the engine. However, the disadvantage of such a structure without transmission or clutch is that the propeller is always fixedly connected to the engine for rotation in all operating conditions, at least the engine is in operating condition, i.e. completely stopped As long as it is not, it cannot be separated from the engine. That is, in an operating state where the engine is stopped to brake the ship (essentially meaning that the fuel supply to the engine has been interrupted), the ship does not stop suddenly on the spot. However, at first, the voyage is continued due to the inertia of the huge mass, and gradually decelerates gradually.

  In this regard, the propeller is clearly no longer driven by the engine. However, the propeller is driven by advancing through the water with a continuous relative speed between the propeller and the water. However, since the propeller is rotatably fixed and connected to the engine and cannot be separated from the engine, the engine is also driven by the propeller in such an operating state. This nevertheless means that since the motor is driven by the propeller, it continues to rotate in the original direction for a considerable amount of time after the fuel supply is stopped.

  The braking of the ship or the acceleration of the reversal of the direction of travel of the ship can only be realized in that the engine is restarted in the direction opposite to the rotation. In the most well-known marine engines, especially the large uniflow scavenging large two-stroke diesel engines, this is the compressed air, referred to in technical terms as starting air, at the right time, ie the right crank angle. Is only possible in that it is pressed into the cylinder liner at a sufficiently high pressure and the engine is restarted in the opposite direction to the desired rotation by the starting air acting on the piston.

  Due to the huge force that the propeller exerts on the piston in the cylinder liner of the engine via the crankshaft so that the engine continues to rotate in the original direction even when the fuel supply is stopped as described above. The engine can be restarted in the opposite direction when the earliest possible maximum possible starting air pressure is sufficient to compensate for the force from the propeller acting on the piston. The engine is set to rotate sufficiently quickly in the opposite direction by the starting air, so that when the fuel supply resumes, the engine can eventually be independently restarted in the opposite direction. When the engine is restarted in the opposite direction of rotation, the propeller that is rotatably fixedly connected to the engine is naturally driven in the opposite direction by the engine as well. This gradually accelerates the braking of the vessel and eventually stops the vessel running or, if desired, the vessel starts to run in the opposite direction.

  The disadvantages of the previously described ship braking and reversing process, which were previously common, are clear. On the other hand, it takes a very long time to brake a ship, particularly for a ship equipped with a low-speed uniflow scavenging large two-stroke diesel engine. This is because, before the engine restarts in the opposite direction, it is necessary to wait for a long time until the ship is sufficiently stalled and slowed down so that the driving of the engine by the propeller is offset by the starting air. is there. This also takes a very long time, especially if you have to brake quickly to ensure that collisions with other ships, icebergs and other obstacles are avoided with certainty and margin in emergency situations, for example. It is a serious drawback. In particular, the famous Titanic tragedy that was not able to brake the ship with plenty of room is still remembered today. Although the Titanic was not driven by a low speed uniflow scavenging large two-stroke diesel engine, the problem is the same in principle.

  Frequent attempts to reverse the engine at the earliest possible point by supplying start-up air to the cylinder liner to minimize the distance covered by the ship when braking or reversing in the opposite direction of travel Has been made. However, the faster the engine is driven by the propeller and moves faster in the original direction, the more start-up air or start-up air energy is needed to start reversing in the opposite direction. This method is not only expensive and energy consuming, but the start-up air must first be generated with a corresponding compressor and stored in the pressure chamber, so that a large part of the total start-up air accumulation is Despite being consumed, it creates the risk that the engine cannot start in the opposite direction. This not only delays braking, but can also be a safety risk. This is because in this situation, it is necessary to supply new starting air again, during which time the engine cannot be started again. This can have serious consequences under certain circumstances because the ship does not have a drive in such situations.

  Accordingly, it is an object of the present invention to provide a method by which a particularly low speed uniflow scavenging large two-stroke diesel engine can be reversed more efficiently and rapidly in the opposite direction. In this way, most of the problems described from the prior art can be avoided. In particular, fatal safety problems known from the prior art can be avoided and engine reversal can be made more economical and energy saving.

  The subject matter of the present invention that fulfills these objectives is characterized by the structure of independent claim 1.

  The dependent claims relate to particularly advantageous embodiments of the invention.

  The present invention relates to a method for controlling rapid reversal or braking of rotation in a first rotational direction of a crankshaft of a reciprocating piston internal combustion engine, in particular top dead center corresponding to a crank angle of 180 ° and 0 ° or 360 °. A cylinder in which a piston is arranged so as to be able to reciprocate between a bottom dead center corresponding to a crank angle of the cylinder and a predetermined pressure is determined by a valve oil pressure using a hydraulic medium, preferably hydraulic oil (hydraulic oil). The present invention relates to a method for controlling a low-speed uniflow scavenging large two-stroke diesel engine having a cylinder having an outlet valve that can be hydraulically operated at an open pressure. According to the invention, the fuel supply to the reciprocating piston internal combustion engine is interrupted during the braking phase, and the hydraulic medium is supplied with a valve hydraulic pressure (valve) of the first outlet valve of the first cylinder at a predetermined maximum opening pressure. are supplied at a first crank angle in the region of the top dead center position of the first piston associated with the first cylinder, whereby the first outlet valve is the earliest and first piston Is automatically released by the valve hydraulic pressure at the second crank angle when passes through the top dead center position.

  The present invention provides a method by which an engine, particularly a low speed uniflow scavenging large two-stroke diesel engine, can be reversed more efficiently and rapidly in the opposite direction of rotation while at the same time further saving valuable start-up air. Offer for the first time. In a particularly preferred embodiment of the method according to the invention, on a ship, restarting in the opposite direction of rotation starts completely without using start-up air (for example using the braking energy provided to the engine by the propeller). It can even be done. This means not only an improvement that cannot be underestimated from an economic point of view, but also a great advancement in terms of safety technology, especially when the method according to the invention is used for reversing or braking a marine engine. To do.

  In practice, in a particularly preferred embodiment, the reciprocating piston internal combustion engine is a marine low speed uniflow scavenging large two stroke diesel engine. The ship here is, for example, a container ship with a super-large engine that has up to 12 cylinders or more and can have power up to 10,000 kW per cylinder or more. is there.

  As is known to those skilled in the art, the piston reciprocates between top dead center and bottom dead center in a cylinder liner that is in the normal operating state of a reciprocating piston internal combustion engine, to the piston and propeller. The propeller is driven by a crankshaft that is operatively fixedly connected. The cylinder cover outlet valve of the cylinder liner is actually hydraulically actuated by the valve oil pressure using a programmable controller having a hydraulic system and electronics. In this respect, the crank angle at which the outlet valve operates can in principle be predetermined as desired by the programmable controller. The engine can be started from a stopped state by actuating a start air valve, or the direction of rotation of the engine can be changed at a sufficiently low rotational speed.

  In order to better understand the present invention, the general operating mode of a reciprocating piston internal combustion engine, which is well known per se, in the normal operating state is briefly and briefly recalled below. Within the framework of this application, a crank angle of 0 ° or 360 ° is specified with the bottom dead center UT, respectively, and a crank angle of 180 ° is specified with the top dead center OT.

  The piston started from the bottom dead center corresponding to the crank angle of 0 ° first moves in the operating state in the direction of OT corresponding to the crank angle of 180 °. When the piston is located near the bottom dead center, the scavenging slit is opened in the lower region of the cylinder liner, and the outlet valve 5 is opened in the normal operation state. The scavenging slit is opened by the piston, and fresh air (fresh air) is supplied to the combustion space of the cylinder liner through the scavenging slit, and at the same time, the piston moves in the direction toward the top dead center through the outlet valve. Exhausted from the combustion space. If the piston passes completely through the scavenging slit and, as a result, the combustion space and the scavenging slit are not in communication, the outlet valve is also closed using the control device at a predetermined crank angle as the cranking angle increases. In the subsequent process, fuel is supplied to the combustion space of the engine by an injection valve. The combustion space is formed by an upper cylinder region, a cylinder cover located above it, and a piston base. This fuel ignites in the air heated by compression in the region of top dead center and then burns, and this energy release increases the pressure in the combustion space.

  After passing through the top dead center, the piston moves again in the direction toward the bottom dead center corresponding to a 360 ° crank angle. Under normal operating and running conditions of the ship, the outlet valve is then reopened and a new working cycle of the cylinder is started with a crank angle considerably greater than 180 °.

  If the ship is to be braked, especially if it is to be braked in the shortest possible distance in the event of an emergency, the reciprocating piston internal combustion engine is set to different operating conditions for braking or reversing in an already known manner. obtain. In the first step, it is known to interrupt the fuel supply to the cylinder liner of the reciprocating piston internal combustion engine. By interrupting the fuel supply, the engine speed is first reduced, thereby causing the first moderate deceleration of the vessel. If no further action is taken, the speed of the ship is substantially reduced due to the friction of the ship in the water. In general, since this friction is relatively small, the speed of the ship decreases very slowly. The propeller is not driven by the reciprocating piston internal combustion engine after the fuel supply is interrupted, but is driven as a turbine by the still existing kinetic energy of the ship, and the propeller is fixedly connected rotatably via the crankshaft. To drive.

  If the control of the outlet valve is maintained unchanged in normal operating conditions and as previously implemented in the prior art, some of the kinetic energy of the ship will be between 0 ° and 180 ° Within the angular range, it is converted to compressive energy in the cylinder, as will be appreciated. However, when the scavenging air enclosed in the cylinder liner subsequently expands during piston movement from top dead center to bottom dead center, this compression energy is again almost completely returned to the ship by the propeller in the form of kinetic energy. It is.

  The present invention starts from this point, and if the braking energy transmitted to the engine by the propeller is used cleverly according to the present invention, the rapid reversal or braking of the engine is particularly free of starting air. Also, at least with a smaller amount of starting air than previously required in the prior art, it is practically possible only by properly controlling the outlet valve and can actually be restarted in the opposite direction. Based on recognition.

  In a preferred embodiment of the control process according to the invention, the second crank angle is a value between 180 ° and 360 °, preferably between 180 ° and 225 ° or between 180 ° and 200 °. A range between the top dead center and the bottom dead center of the first piston, particularly preferably at a second crank angle between 180 ° and 190 ° after the top dead center of the first piston. Selected within.

  In order to further improve the braking effect on the reverse rotation, the first outlet valve is closed again at a third crank angle in the region between the second crank angle and the bottom dead center of the first piston, A predetermined vacuum is formed in one cylinder.

  Depending on the stage of engine reversal where this action is taken, two additional positive effects can be substantially brought about.

  If the formation of a vacuum in the first cylinder takes place in the first rotational direction during the braking phase of the rotation of the reciprocating piston internal combustion engine and the third crank angle is selected accordingly, the third With the proper choice of crank angle, a vacuum can be created in the first cylinder by closing the outlet valve. As a result, the formation of a vacuum facilitates braking of the rotation of the reciprocating piston internal combustion engine in the first rotational direction. This therefore results in at least a slight suction effect on the piston, resulting in a corresponding piston motion braking which further removes the kinetic energy from the engine to facilitate braking.

  On the other hand, by closing the first outlet valve at the third crank angle, a vacuum is created in the first cylinder, and as a result, the vacuum formation in the first cylinder causes the second cylinder to be supplied with fuel. The third crank angle is the reverse of the reciprocating piston internal combustion engine following the braking phase so that the restart of the reciprocating piston internal combustion engine in a second rotational direction opposite to the first rotational direction initiated is facilitated. It can also be selected in stages. This results in a braking suction effect in the first cylinder relative to the first rotational direction of the engine, so that the engine is restarted, i.e. in a new second rotational direction opposite to the first rotational direction. It means that reversal is facilitated or facilitated, so that early reversal is possible or start-up air that can still be needed is minimized or completely eliminated.

  A further additional or alternative measure of the method according to the invention is the fourth crank angle between bottom dead center and top dead center, preferably reached after the end of the supply of scavenging air to the cylinder. With a crank angle of 4, it has a closed first outlet valve.

  Even with the last mentioned measures, there are virtually two additional positive effects depending on the engine reversal stage in which the outlet valve is closed at the fourth crank angle. .

  On the other hand, by closing the first outlet valve at the fourth crank angle, overpressure is accumulated in the first cylinder, and as a result, reciprocating piston internal combustion in the first rotational direction is caused by the accumulation of overpressure. The fourth crank angle may be selected during the braking phase of the reciprocating piston internal combustion engine rotation so as to facilitate braking of the engine rotation. Also, the conversion of kinetic energy into pressure energy actually removes kinetic energy from the engine due to pressure buildup in the cylinder, which effectively promotes braking of the engine in the first rotational direction. .

  On the other hand, by closing the first outlet valve at the fourth crank angle, overpressure is accumulated in the first cylinder, and as a result, overpressure accumulation in the first cylinder is initiated by the fuel supply. The fourth crank angle in the reverse rotation phase of the reciprocating piston internal combustion engine following the braking phase so as to be properly harmonized with the restart of the reciprocating piston internal combustion engine in the second rotational direction opposite to the first rotational direction. When is selected, restart opposite to the direction of rotation is effectively facilitated by the accumulation of overpressure in the first cylinder.

  This causes a braking pressure effect in the first cylinder relative to the first direction of rotation of the engine, so that the engine is restarted, i.e. in a new second direction of rotation opposite to the first direction of rotation. It means that reversal is facilitated or facilitated, so that early reversal is possible or start-up air that can still be needed is minimized or completely eliminated.

  In particular, when the reversal occurs particularly rapidly, or when, for example, emergency braking of the ship is necessary, or when it is separately necessary to carry out the method according to the invention very quickly, it was started in the reversal phase. The restarting of the reciprocating piston internal combustion engine in the second rotational direction opposite to the first rotational direction naturally involves introducing a predetermined minimum amount of starting air into at least one cylinder of the reciprocating piston internal combustion engine. Can be further promoted. Thereby, reverse rotation in the second rotation direction or braking from the first rotation direction can be further accelerated.

  In particular, but not limited to this, when a very rapid procedure is not required, such as in an emergency, the reciprocating piston internal combustion engine is used to accelerate the restarting of the second rotational direction in the reverse rotation stage. It is also possible to introduce continuously into only some of the cylinders. This is preferably introduced only into the selected single cylinder and not into the other cylinders.

  With the method according to the invention, as described above, the reciprocating piston internal combustion engine is restarted in the second direction of rotation opposite to the first direction of rotation started in the reverse phase without using starting air. Is possible. This is because the kinetic energy returned to the engine by the propeller is ideally used by skillfully controlling the outlet valve.

  In practice, the reciprocating piston internal combustion engine comprises a plurality of cylinders which are arranged in a manner known per se, at least partly simultaneously with different crank angles in each case. Thereby, the measures mentioned here for accelerating the braking or reversing of the engine can be taken simultaneously so that the cumulative effect of the different measures arises.

  It is possible that the embodiments of the invention described in this application can be combined in an appropriate manner depending on the application, and that the specific embodiments described are only to be understood as examples. Understood. The person skilled in the art will immediately recognize the concise and advantageous further improvements of the described embodiments of the invention and understand that such concise further improvements are naturally covered by the present invention.

Claims (12)

Control method for rapid reversal or braking of rotation in a first rotational direction of a crankshaft of a reciprocating piston internal combustion engine, in particular a low speed uniflow scavenging large two-stroke diesel engine, each of which is 180 A cylinder having a piston arranged to reciprocate between a top dead center corresponding to a crank angle of 0 ° and a bottom dead center corresponding to a crank angle of 0 ° or 360 °; In a control method, comprising an outlet valve that can be hydraulically actuated at a predetermined opening pressure through a valve oil pressure with a medium, preferably hydraulic oil,
Fuel supply to the reciprocating piston internal combustion engine is interrupted in a braking phase, and the hydraulic medium is at a predetermined maximum opening pressure of a valve oil pressure of a first outlet valve of a first cylinder, and the first Provided with a first crank angle in the region of the top dead center position of the first piston relative to the cylinder of the first piston, whereby the first outlet valve is the earliest and the first piston is A control method characterized in that, when passing through the top dead center position, the valve is automatically opened by the valve hydraulic pressure at the second crank angle.   The second crank angle is a value between 180 ° and 360 °, preferably between 180 ° and 225 ° or between 180 ° and 200 °, particularly preferably the first piston. The second crank angle between 180 ° and 190 ° after top dead center is within a range between top dead center and bottom dead center of the first piston. Control method.   The first outlet valve is closed again at a third crank angle in a region between the second crank angle and the bottom dead center of the first piston, and the predetermined pressure is set in the first cylinder. The control method according to claim 1, wherein a vacuum is formed.   Closing the first outlet valve at the third crank angle creates a vacuum in the first cylinder, resulting in rotation of the reciprocating piston internal combustion engine in the first rotational direction. 4. The control of claim 3, wherein the third crank angle is selected during a braking phase of rotation of the reciprocating piston internal combustion engine in the first rotational direction so that braking is aided by the formation of the vacuum. Method.   Closing the first outlet valve at the third crank angle creates a vacuum in the first cylinder so that the first rotation initiated in the second cylinder by fuel supply The third crank angle is in the braking phase so that restarting of the reciprocating piston internal combustion engine in a second rotational direction opposite to the direction is assisted by the formation of the vacuum in the first cylinder. 4. The control method according to claim 3, wherein the control method is selected in a subsequent reversing stage of the reciprocating piston internal combustion engine.   The first outlet valve is closed at a fourth crank angle between bottom dead center and top dead center, preferably the fourth crank angle reached after the end of the supply of scavenging air to the cylinder. The control method according to any one of claims 1 to 5.   By closing the first outlet valve at the fourth crank angle, an overpressure is accumulated in the first cylinder, resulting in the rotation of the reciprocating piston internal combustion engine in the first rotational direction. 7. A control method according to claim 6, wherein the fourth crank angle is selected during a braking phase of rotation of the reciprocating piston internal combustion engine so that braking is aided by the accumulation of overpressure.   By closing the first outlet valve at the fourth crank angle, an overpressure is accumulated in the first cylinder, resulting in the first cylinder being started in the second cylinder by fuel supply. The fourth crank angle is braked so that restart of the reciprocating piston internal combustion engine in a second rotational direction opposite to the rotational direction is aided by the accumulation of the overpressure in the first cylinder. The control method according to claim 6, wherein the control method is selected in a reverse phase of the reciprocating piston internal combustion engine following a phase.   The restart of the reciprocating piston internal combustion engine in the second rotational direction opposite to the first rotational direction initiated in the reverse rotation stage causes a predetermined minimum amount of at least one cylinder of the reciprocating piston internal combustion engine to 9. A control method according to any one of claims 1 to 8, which is aided by introducing start-up air.   To help restart the second direction of rotation in the reverse phase, the start-up air is supplied to only some of the cylinders of the reciprocating piston internal combustion engine, preferably only to a single selected cylinder. The control method according to claim 9, wherein the control method is continuously introduced and is not introduced to other cylinders.   9. The reciprocating piston internal combustion engine is restarted in the second direction of rotation opposite to the first direction of rotation started in the reverse rotation stage without using start air. The control method according to any one of the above.   The control method according to any one of claims 1 to 11, wherein the reciprocating piston internal combustion engine is a ship drive unit.