JP2013124652A - Torsional vibration stress reduction control device, marine vessel having the same, and torsional vibration stress reduction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torsional vibration stress reduction control device for reducing torsional vibration stress by simple control.SOLUTION: A torsional vibration stress reduction control device 50 is configured to reduce torsional vibration stress generated in a propulsion shafting 10 in a marine vessel 100 including a propulsion shafting 10 which rotates integrally with a propulsion propeller 11, a main engine 20 for driving the propulsion shafting 10, and a supercharger 30 which has a turbine 31 driven by exhaust 27 expelled from the main engine 20 and which uses the rotational force of the turbine 31 as motive power to compress new air and supply scavenged air 24 to the main engine 20. The pressure of the scavenged air 24 is reduced when the torsional vibration stress is a predetermined value or greater.

Description

  The present invention relates to a torsional vibration stress reduction control device for reducing torsional vibration stress generated in a propulsion shaft system of a ship, and a ship equipped with this torsional vibration stress reduction control device. The present invention also relates to a torsional vibration stress reduction method for reducing torsional vibration stress.

  The main engine mounted on the ship is a structure that converts the reciprocating motion of the pistons into rotational motion by the crankshaft.Since multiple pistons reciprocate at different phases, the force applied to the crankshaft depends on the rotational angle position of the crankshaft. In contrast, the torsional stress generated in the propulsion shaft system including the crankshaft also varies depending on the rotation angle position of the crankshaft. As a result, the torsional stress generated in the propulsion shaft system varies mainly in synchronization with the rotation of the main engine. On the other hand, the propulsion shaft system has a natural frequency for each vibration mode. When the rotation of the main engine coincides with the natural frequency of the propulsion shaft system, the torsional stress described above increases at a stretch, and in some cases, the propulsion shaft system may be damaged. For the torsional vibration stress at the time of resonance, countermeasures have been studied conventionally.

  As one of countermeasures against torsional vibration stress, there is a method of changing the natural frequency of the propulsion shaft system by changing the balance of the size and weight of the members constituting the propulsion shaft system. According to this method, the peak of the torsional vibration stress can be moved to a low rotational speed that is not frequently used for ship operation, or the value of the torsional vibration stress can be lowered. However, a change that reduces the shaft diameter of the component of the propulsion shaft system has a problem that the strength decreases, and a change that increases the shaft diameter increases the manufacturing cost and the weight. . In addition, there is a method of expanding the allowable value of torsional vibration stress by changing the material of the constituent members of the propulsion shaft system to a material having high strength. There is a possibility that this problem may occur. As described above, the measures for changing the constituent members of the propulsion shaft system are likely to cause problems in terms of manufacturing cost and strength.

  On the other hand, measures for avoiding or reducing torsional vibration stress from the control surface without changing the constituent members of the propulsion shaft system have been studied. For example, Patent Document 1 discloses a dangerous rotational speed range avoidance countermeasure device that escapes early from a dangerous rotational speed range through which the main engine passes during acceleration by temporarily releasing a governor scavenging pressure limiter. Yes.

  Further, Patent Document 2 discloses a crankshaft torsion prevention device configured to increase the supercharging pressure when the engine rotational speed becomes equal to or higher than a predetermined rotational speed. According to this device, the force acting upward on the crankshaft is reduced, and the torsion of the crankshaft is reduced.

  Patent Document 3 discloses a diesel engine crankshaft torsional vibration suppression device configured to adjust the fuel injection timing or the fuel injection period when the rotational speed of the diesel engine is within the range of the resonant rotational speed. It is disclosed. According to this apparatus, the vibration generating torque component is reduced and the resonance stress can be reduced.

Japanese Utility Model Publication No. 06-39072 JP 2005-273571 A Japanese Patent Laid-Open No. 03-275958

  However, the invention described in Patent Document 1 is not a fundamental solution because the magnitude of the torsional vibration stress itself does not change. Further, the invention described in Patent Document 2 is a countermeasure in a region where the inertial force is dominant with respect to torsional vibration where the engine speed is high and the engine load is low, and the object is limited. In particular, it is difficult to apply to engines mainly for low speed and high load operation such as marine main engines. In addition, the invention described in Patent Document 3 has a mechanism for adjusting the fuel injection timing and the injection period as well as complicated control because the object of control is fuel injection and control directly related to the performance of the main engine. There is a problem that must be done.

  Therefore, an object of the present invention is to provide a torsional vibration stress reduction control device that can reduce torsional vibration stress by simple control.

  A torsional vibration stress reduction control device according to the present invention includes a propulsion shaft system that rotates integrally with a propeller for propulsion, a main machine that drives the propulsion shaft system, and a turbine that is driven by exhaust gas discharged from the main machine. And a supercharger that compresses fresh air using the rotational force of the turbine as a motive power and supplies the scavenged air to the main engine, for reducing torsional vibration stress generated in the propulsion shaft system The torsional vibration stress reduction control device is configured to reduce the scavenging pressure when the torsional vibration stress is a predetermined value or more.

  According to such a configuration, since the scavenging pressure is reduced when the torsional vibration stress is equal to or higher than a predetermined value, there is a risk of reducing the efficiency of the main engine, but the torsional vibration stress can be surely reduced.

  In the torsional vibration stress reduction control apparatus, the scavenging pressure may be reduced by reducing the pressure of the exhaust gas that drives the turbine of the supercharger.

  Further, in the above torsional vibration stress reduction control device, the supercharger has an exhaust passage for guiding the exhaust discharged from the main engine to the turbine, and a bypass valve provided in the exhaust passage. The exhaust pressure may be reduced by opening the bypass valve.

  In the above torsional vibration stress reduction control device, the supercharger has a variable nozzle in the front stage of the turbine, and the exhaust pressure is reduced by changing the opening of the variable nozzle. It may be configured to be performed.

  The torsional vibration stress reduction control device may further include a scavenging bypass valve that bypasses scavenging supplied from the supercharger to the main engine, and the scavenging pressure is reduced by adjusting the scavenging bypass valve. It may be configured to be performed.

  The torsional vibration stress reduction control device may be configured to determine whether or not the torsional vibration stress is a predetermined value or more based on a rotation speed of the main machine.

  The torsional vibration stress reduction control apparatus may be configured to determine whether or not the torsional vibration stress is a predetermined value or more by measuring the torsional vibration stress.

  Furthermore, the ship according to the present invention includes any one of the above torsional vibration stress reduction control devices.

  Furthermore, the torsional vibration stress reducing method according to the present invention is driven by a propulsion shaft system that rotates integrally with a propeller for propulsion, a main unit that drives the propulsion shaft system, and exhaust gas discharged from the main unit. A torsional vibration stress for reducing a torsional vibration stress generated in the propulsion shaft system in a ship having a turbine, and a supercharger that compresses scavenging using the rotational force of the turbine as a power and supplies the compressed scavenging gas to the main engine In this method, it is determined whether or not the torsional vibration stress is equal to or greater than a predetermined value, and when it is determined that the torsional vibration stress is equal to or greater than a predetermined value, the function of the supercharger is reduced.

  According to the torsional vibration stress reduction control device according to the present invention, the torsional vibration stress can be reduced by simple control.

FIG. 1 is a schematic view of a ship according to an embodiment of the present invention. FIG. 2 is a graph showing the relationship between the rotational speed of the main machine and the torsional vibration stress. FIG. 3 is a graph showing a control curve of the variable nozzle under the control of the scavenging air pressure control device. FIG. 4 is a flowchart showing the operation of the torsional vibration stress reduction control device. FIG. 5 is a graph showing the relationship between the load of the main engine and the scavenging pressure when the control by the torsional vibration stress reduction control device is performed. FIG. 6 is a graph showing the relationship between the rotational speed of the main engine and the torsional vibration stress when the control by the torsional vibration stress reduction control device is performed.

  Hereinafter, embodiments of the present invention will be described. In the following description, the same or corresponding components are denoted by the same reference symbols throughout the drawings, and redundant description is omitted.

  FIG. 1 is a schematic view of a ship 100 according to an embodiment of the present invention. As shown in FIG. 1, the ship 100 includes a propulsion shaft system 10, a main engine 20, a supercharger 30, a scavenging air pressure control device 40, and a torsional vibration stress reduction control device 50. Hereinafter, each of these components will be described in order.

  The propulsion shaft system 10 is a series of shaft systems that rotate integrally with the propeller 11 for propulsion. The propulsion shaft system 10 includes a propeller 11 for propulsion, a propeller shaft 12 coupled to the propeller 11, an intermediate shaft 13 coaxially coupled to the propeller shaft 12, and the vicinity of the main shaft 20 of the intermediate shaft 13 in order from the left side of FIG. A flywheel 14 attached to the crankshaft, a crankshaft 15 which is a component of the main machine 20 and connected to the intermediate shaft 13, and a tuning attached to the end of the crankshaft 15 opposite to the intermediate shaft 13 A wheel 16 is used. The tuning wheel 16 is attached as necessary. The propulsion shaft system 10 receives rotational power from the main machine 20 via the crankshaft 15 and rotates as a whole.

  The main machine 20 is a device that drives the propulsion shaft system 10. The main machine 20 according to the present embodiment is a uniflow type diesel engine. The main machine 20 is driven as follows. First, scavenging (fresh air) 24 is supplied from the scavenging pipe 21 through the scavenging port 22 into the cylinder 23. The supplied scavenging air 24 is compressed as the piston 25 rises, and the fuel injected from the fuel injection nozzle 26 ignites and explodes. Due to this explosion, the piston 25 is pushed back downward, and then the exhaust (air mixture after combustion) 27 is discharged to the outside from the exhaust port 28 at an appropriate timing. The crankshaft 15 is connected to the lower end of the piston 25, and the crankshaft 15 rotates as the piston 25 repeats the vertical movement as described above.

  The solid line in FIG. 2 shows an example of the relationship between the rotational speed of the main machine 20 and the torsional vibration stress (torsional vibration stress curve 101). The horizontal axis in FIG. 2 is the rotational speed of the main machine 20, and the vertical axis is the torsional vibration stress. As an example to the last, in the case of FIG. 2, the 65% rotational speed of the main machine 20 is the resonance rotational speed, and the torsional vibration stress increases at a stretch at that rotational speed.

  Here, the broken lines in FIG. 2 indicate the first danger curve 102 and the second danger curve 103. Of these, the first danger curve 102 is a curve indicating that there is a possibility that fatigue failure may occur in the propulsion shaft system if continuous operation is performed in a state where a torsional vibration stress exceeding this is generated. Further, the second risk curve 103 is a curve indicating that a propulsion shaft system in which a torsional vibration stress exceeding the second risk curve 103 cannot be adopted for a ship. In actual ship operation, a rotational speed region called a barred range is set. The bird range refers to a rotation speed region in which continuous use of the main engine is prohibited in actual operation. In the present embodiment, a region between intersections where the first risk curve 102 and the torsional vibration stress curve 101 intersect is set as a bird range.

  The supercharger 30 is a device that draws in fresh air and supplies the compressed scavenging air 24 to the main engine 20 via the scavenging pipe 21. The supercharger 30 is mainly configured by a turbine 31, a variable nozzle 32, a compressor 33, an exhaust passage 34, and a bypass valve 35. The exhaust 27 discharged from the main machine 20 is introduced into the variable nozzle 32 through the exhaust passage 34. The variable nozzle 32 is located in the front stage of the turbine 31 and includes a plurality of nozzle vanes (not shown). The nozzle vane is configured to change the angle, and the opening degree of the variable nozzle 32 can be adjusted by changing the nozzle vane angle. When the opening of the variable nozzle 32 increases, the pressure (dynamic pressure) of the supplied exhaust 27 decreases, and when the opening of the variable nozzle 32 decreases, the pressure of the supplied exhaust 27 increases.

  The exhaust 27 that has passed through the variable nozzle 32 rotates the turbine 31. The turbine 31 and the compressor 33 are connected by a rotor shaft 36, and the compressor 33 rotates as the turbine 31 rotates. The compressor 33 compresses fresh air taken in from the outside and supplies the scavenging air 24 to the main engine 20 via the scavenging pipe 21. If the rotational speed of the compressor 33 increases, the scavenging air 24 at the outlet of the compressor 33 is compressed. The pressure increases, thereby increasing the pressure in the scavenging pipe 21 (hereinafter referred to as “scavenging air pressure”). The exhaust passage 34 is provided with a bypass valve 35. When the bypass valve 35 is opened, a part of the exhaust 27 guided to the turbine 31 is bypassed to the outside, and the pressure of the supplied exhaust 27 is reduced. The bypass valve 35 may be an open / close switching (ON-OFF switching) type valve that can be switched between open and closed, and is an opening adjustment type valve that can arbitrarily adjust the opening. Also good.

  The scavenging air pressure control device 40 is a device that controls the scavenging air pressure, and controls the scavenging air pressure by controlling the pressure of the exhaust 27 that rotates the turbine 31. More specifically, the scavenging air pressure control device 40 controls the pressure of the exhaust 27 by adjusting the opening degree of the bypass valve 35 and the variable nozzle 32, thereby controlling the scavenging air pressure. The scavenging air pressure control device 40 is provided for the purpose of improving the efficiency of the main engine 20 by increasing the scavenging air pressure at the partial load of the main engine. The scavenging air pressure control device 40 generates a control signal for controlling the bypass valve 35 and the variable nozzle 32 based on a control curve 104 described later, and sends the control signal to the torsional vibration stress reduction control device 50 as shown in FIG. Configured to send. Further, the scavenging air pressure control device 40 can acquire a signal related to the rotation speed of the main engine 20 from the tachometer 41 and can acquire a signal related to the fuel rack amount (fuel injection amount) from the fuel index transmitter 61 attached to the fuel pump 60. The scavenging air pressure meter 42 can acquire a signal related to the scavenging air pressure.

  Here, the control (control signal generation method) by the scavenging air pressure control device 40 will be described focusing on the case where the variable nozzle 32 is controlled. The solid line in FIG. 3 shows an example of the control curve 104 of the variable nozzle 32. The horizontal axis in FIG. 3 is the load of the main machine 20, and the vertical axis is the scavenging pressure. Also, of the two broken lines shown in FIG. 3, the straight line on the higher scavenging pressure is the scavenging line when the opening of the variable nozzle 32 is normally minimum (hereinafter referred to as the “first scavenging line”). 105, and the straight line on the low scavenging pressure side is a scavenging line (hereinafter referred to as “second scavenging line”) 106 when the opening of the variable nozzle is normally maximum. First, the scavenging pressure control device 40 acquires the rotational speed of the main engine 20 from the tachometer 41, acquires the fuel rack amount from the fuel index transmitter 61, and determines the main engine 20 from the acquired rotational speed and fuel rack amount. Estimate the load. The main engine load may be estimated by obtaining a signal related to the in-cylinder pressure or a signal related to the turbocharger rotation. Then, the scavenging air pressure corresponding to the estimated load of the main engine 20 is read from FIG. Then, the variable nozzle 32 is controlled (a control signal is generated) so that the scavenging air pressure read from FIG. Note that the actual opening of the variable nozzle varies slightly depending on atmospheric conditions and the like.

  Thus, since the scavenging pressure control device 40 generates the control signal based on FIG. 3, if the scavenging pressure control device 40 alone performs control, the scavenging pressure is controlled as shown in FIG. It will change along the curve 104. That is, in the example of FIG. 3, when the load of the main machine 20 is smaller than the 75% load, the opening degree of the variable nozzle 32 is the minimum, and the scavenging pressure changes along the first scavenging pressure line 105. And if the load of the main machine 20 exceeds 75% load, the opening degree of the variable nozzle 32 will become large gradually, and, thereby, the rate of a raise of scavenging pressure will fall. When the load of the main engine 20 finally reaches 100% load, the opening degree of the variable nozzle 32 becomes maximum, and the scavenging pressure intersects the second scavenging pressure line 106. Although the case where only the variable nozzle 32 is controlled has been described above, the bypass valve 35 can be similarly controlled. In particular, when the bypass valve 35 is an opening adjustment type valve, it is the same as the variable nozzle 32 in that the opening can be finely adjusted. Therefore, the control can be performed using a control curve similar to FIG. it can. When the bypass valve 35 is an open / close switching type valve, when the load on the main engine 20 reaches a certain value (for example, 75% load), control is performed so that the bypass valve 35 is switched from fully closed to fully open. Is called.

  The torsional vibration stress reduction control device 50 is a control device for reducing torsional vibration stress. As shown in FIG. 1, the torsional vibration stress reduction control device 50 receives a control signal for controlling the variable nozzle 32 and the bypass valve 35 from the scavenging air pressure control device 40, and the rotational speed of the main engine 20 from the tachometer 41. And a control signal can be transmitted to the variable nozzle 32 and the bypass valve 35. The torsional vibration stress reduction control device 50 operates as follows.

  FIG. 4 is a flowchart showing the operation of the torsional vibration stress reduction control device 50. First, as shown in FIG. 4, the torsional vibration stress reduction control device 50 determines whether or not the torsional vibration stress is equal to or greater than a predetermined value (step S1). In the present embodiment, the rotational speed of the main machine 20 is acquired from the tachometer 41, and it is determined whether or not the torsional vibration stress is greater than or equal to a predetermined value depending on whether or not the rotational speed of the main machine 20 is in the dangerous rotational speed region. . Here, the critical rotational speed region is a region of rotational speed when the torsional vibration stress is equal to or greater than a predetermined value, and is set in advance based on the torsional vibration stress curve shown in FIG. 2 (see FIG. 6). In the present embodiment, the dangerous rotation speed region is set to a region slightly wider than the above-described bird range. In this embodiment, whether or not the torsional vibration stress is greater than or equal to a predetermined value is determined based on the rotational speed of the main engine 20, but a torsional stress measuring device is provided in the propulsion shaft system 10 to directly measure the torsional vibration stress. You may make it determine by measuring a value. In determining whether the torsional vibration stress is equal to or greater than a predetermined value, a predetermined value that does not depend on the rotational speed of the main machine 20 may be set as the predetermined value, and a value that varies according to the rotational speed of the main machine 20 may be set to the predetermined value. It is good.

  Subsequently, when it is determined that the torsional vibration stress is not equal to or greater than the predetermined value (NO in step S1), the torsional vibration stress reduction control device 50 directly receives the control signal received from the scavenging air pressure control device 40 and the variable nozzle 32 and the bypass valve 35. (Step S3). That is, at this time, the variable nozzle 32 and the bypass valve 35 are controlled by the scavenging air pressure control device 40. On the other hand, when it is determined that the torsional vibration stress is equal to or greater than the predetermined value (YES in step S1), the torsional vibration stress reduction control device 50 transmits a control signal that maximizes the opening degree to the variable nozzle 32. Then, a control signal for maximizing the opening degree is transmitted to the opening adjustment type bypass valve 35, and a control signal for opening the valve is transmitted to the opening / closing switching type bypass valve 35. (Step S2). That is, when it is determined that the torsional vibration stress is equal to or greater than a predetermined value, the function of the supercharger 30 is reduced so that the pressure of the exhaust gas supplied to the turbine 31 is reduced to the maximum. To control. The above is the control by the torsional vibration stress reduction control device 50.

  When the torsional vibration stress reduction control device 50 performs the above control, the scavenging pressure changes as shown in FIG. The solid line in FIG. 5 shows the relationship between the load of the main engine 20 and the scavenging pressure (scavenging pressure curve 107) when the control by the torsional vibration stress reduction control device 50 is performed. The horizontal axis of FIG. 5 is the load of the main machine 20, and the vertical axis is the scavenging pressure. FIG. 5 is a diagram when only the variable nozzle 32 is controlled, as in the case of FIG. 3. The broken lines shown in FIG. 5 are the first scavenging line 105 and the second scavenging line 106 shown in FIG. As shown in FIG. 5, when the load of the main engine 20 is smaller than the load corresponding to the dangerous rotational speed region, the control signal of the scavenging air pressure control device 40 is transferred to the variable nozzle 32 as it is. As with the transition of the control curve 104, the scavenging air pressure changes along the first scavenging air pressure line 105. When the load of the main engine 20 is a load corresponding to the dangerous rotation speed region, a control signal for maximizing the opening degree is transmitted to the variable nozzle 32. Transition along the two scavenging line 106. Further, when the load of the main engine 20 is larger than the load corresponding to the dangerous rotation speed region, the control signal of the scavenging air pressure control device 40 is transferred to the variable nozzle 32 as it is, so that the control curve 104 shown in FIG. In the same manner as the transition, the scavenging air pressure changes along the first scavenging air pressure line 105 until the load of the main engine 20 becomes 75% load, and then changes toward the second scavenging air pressure line 106. As described above, according to the control of the torsional vibration stress reduction control device 50, when the torsional vibration stress is greater than or equal to a predetermined value (when the main engine 20 is at a dangerous rotational speed), the scavenging air pressure is reduced.

  As a result of the scavenging pressure changing as shown in FIG. 5 under the control of the torsional vibration stress reduction controller 50, the torsional vibration stress changes as shown in FIG. The solid line in FIG. 6 shows the relationship (torsional vibration stress curve 108) between the rotational speed of the main engine 20 and the torsional vibration stress when the control by the torsional vibration stress reduction control device 50 is performed. The horizontal axis of FIG. 6 is the rotational speed of the main machine 20, and the vertical axis is the torsional vibration stress. Here, of the two curves shown by the one-dot broken line in FIG. 6, the curve having the larger torsional vibration stress is the same as the torsional vibration stress curve 101 in FIG. 2, and the opening of the variable nozzle 32 is the smallest. This is a torsional vibration stress curve (hereinafter referred to as a “first torsional vibration stress curve”) 109 during normal operation (so-called normal operation). Further, the curve on the side where the torsional vibration stress is small is the torsional vibration stress curve when the opening degree of the variable nozzle 32 is maximum (that is, when the scavenging pressure is lowered) (hereinafter referred to as “second torsional vibration stress curve”). ) 110. Further, as in the case of FIG. 2, the first danger curve 102 and the second danger curve 103 are also drawn in FIG. 6.

  Based on the above, the transition of the torsional vibration stress when the control by the torsional vibration stress reduction control device 50 is performed will be described with reference to FIG. When the rotational speed of the main engine 20 is smaller than the critical rotational speed region, the variable nozzle 32 is controlled so that the opening degree is minimized, so that the torsional vibration stress changes along the first torsional vibration stress curve 109. When the rotational speed of the main engine 20 enters the dangerous rotational speed region, the variable nozzle 32 is controlled so that the opening degree is maximized, so that the scavenging pressure is reduced at a stretch and the torsional vibration stress is reduced at a stretch. The torsional vibration stress changes along the second torsional vibration stress curve 110 while the rotation speed of the main engine 20 is in the critical rotation speed region. Further, when the rotational speed of the main engine 20 is larger than the critical rotational speed region, the variable nozzle 32 is controlled so as to minimize the opening, so that the torsional vibration stress returns to the original and the first torsional vibration stress. Transition along curve 109. As described above, according to the control by the torsional vibration stress reduction control device 50, the torsional vibration stress can be reduced in the dangerous rotational speed region (originally in the region where the torsional vibration stress becomes high).

  In the above, the case where the torsional vibration stress reduction control device 50 controls the variable nozzle 32 has been described with reference to FIGS. 5 and 6. However, the case where only the bypass valve 35 is controlled and the variable nozzle 32 and the bypass valve 35 are controlled. Similar results are obtained when both are controlled. Even if the bypass valve 35 is an opening adjustment type valve, the result is not different depending on the type of the valve because the bypass valve 35 is fully opened when the rotational speed of the main engine 20 enters the dangerous rotational speed region. As described above, the control by the torsional vibration stress reduction control device 50 of the present embodiment is very simple because the torsional vibration stress can be reduced only by adjusting the opening of the variable nozzle 32 and the bypass valve 35. It can be said that it is control. In the variable nozzle and the opening adjustment type valve, the nozzle / valve opening adjustment at the dangerous rotational speed may be changed stepwise or gradually in order to realize stable control.

  As described above, according to the torsional vibration stress reduction control device 50 of the present embodiment, the torsional vibration stress can be reduced in a region where the torsional vibration stress is originally high. Even the propulsion shaft system 10 that exceeds the two danger curves 103 can be used in the ship 100 without changing the constituent members of the propulsion shaft system 10. Further, as apparent from the comparison between FIG. 6 and FIG. 2, according to the control of the torsional vibration stress reduction control device 50, the range of the bird range can be narrowed, and more efficient operation is possible. Moreover, since the torsional vibration stress reduction control device 50 according to the present embodiment reduces the torsional vibration stress from the control surface, it is not necessary to change the components of the propulsion shaft system 10.

  As mentioned above, although the ship 100 which concerns on embodiment of this invention was demonstrated, a concrete structure is not restricted to these embodiment, Even if there is a design change etc. of the range which does not deviate from the summary of this invention, this book Included in the invention. For example, in the above embodiment, the pressure of the exhaust 27 is reduced in order to reduce the scavenging air pressure, but the scavenging air pressure may be reduced by adjusting the angle of the guide vane provided at the inlet of the compressor 33. Good. Further, a scavenging air bypass valve that bypasses the scavenging gas supplied from the supercharger to the main engine may be provided at the compressor outlet, and the scavenging air pressure may be reduced by adjusting the scavenging gas bypass valve.

  In the above embodiment, the torsional vibration stress reduction control device 50 and the scavenging air pressure control device 40 are arranged in series. However, these devices are arranged in parallel, and the variable nozzle 32 and the bypass valve 35 are connected from both devices. You may comprise so that a signal may be transmitted directly.

  Since the torsional vibration stress reduction control device according to the present invention can reduce the torsional vibration stress by simple control, it is useful in technical fields such as ships.

DESCRIPTION OF SYMBOLS 10 Propulsion shaft system 11 Propeller 20 Main machine 24 Scavenging 27 Exhaust 30 Supercharger 31 Turbine 32 Variable nozzle 33 Compressor 34 Exhaust passage 35 Bypass valve 50 Torsional vibration stress reduction control device 100 Ship

Claims (9)

A propulsion shaft system that rotates integrally with a propeller for propulsion, a main machine that drives the propulsion shaft system, and a turbine that is driven by exhaust gas discharged from the main machine, and using the rotational force of the turbine as power A torsional vibration stress reduction control device for reducing torsional vibration stress generated in the propulsion shaft system in a ship equipped with a supercharger that compresses fresh air and supplies scavenging air to the main engine,
A torsional vibration stress reduction control device configured to reduce the scavenging pressure when the torsional vibration stress is equal to or greater than a predetermined value.   The torsional vibration stress reduction control device according to claim 1, wherein the reduction of the scavenging pressure is performed by reducing the pressure of the exhaust that drives a turbine of the supercharger. The supercharger has an exhaust passage that guides exhaust discharged from the main engine to the turbine, and a bypass valve provided in the exhaust passage,
The torsional vibration stress reduction control device according to claim 2, wherein the exhaust pressure is reduced by opening the bypass valve. The supercharger has a variable nozzle in the front stage of the turbine,
The torsional vibration stress reduction control device according to claim 2, wherein the exhaust pressure is reduced by changing an opening of the variable nozzle. A scavenging bypass valve for bypassing scavenging supplied from the supercharger to the main engine;
The torsional vibration stress reduction control device according to claim 1, wherein the scavenging pressure is reduced by adjusting the scavenging bypass valve.   The torsional vibration stress reduction control device according to any one of claims 1 to 4, wherein whether or not the torsional vibration stress is equal to or greater than a predetermined value is determined based on a rotation speed of the main machine.   The torsional vibration stress reduction control device according to any one of claims 1 to 4, wherein whether the torsional vibration stress is equal to or greater than a predetermined value is determined by measuring the torsional vibration stress.   The ship provided with the torsional stress reduction control apparatus as described in any one of Claims 1 thru | or 7. A propulsion shaft system that rotates integrally with a propeller for propulsion, a main machine that drives the propulsion shaft system, and a turbine that is driven by exhaust gas discharged from the main machine, and using the rotational force of the turbine as power A torsional vibration stress reducing method for reducing torsional vibration stress generated in the propulsion shaft system in a ship equipped with a supercharger that compresses fresh air and supplies scavenging air to the main engine,
A torsional vibration stress reduction method for determining whether or not the torsional vibration stress is greater than or equal to a predetermined value and reducing the function of the supercharger when it is determined that the torsional vibration stress is greater than or equal to a predetermined value.

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