CN111852654A

CN111852654A - Monitoring system

Info

Publication number: CN111852654A
Application number: CN202010322094.XA
Authority: CN
Inventors: 森勇人; 猿渡洋平; 穴井恒平; 柴田隼平; 赤荻祐亮
Original assignee: Hitachi Zosen Corp
Current assignee: Hitachi Shipbuilding Marine Prime Motors Co ltd
Priority date: 2019-04-25
Filing date: 2020-04-22
Publication date: 2020-10-30
Anticipated expiration: 2040-04-22
Also published as: JP7208099B2; JP2020180586A; CN111852654B; TW202039993A; KR20200125516A

Abstract

A monitoring system (76) of the present invention includes a throttle valve (75), a lead-out flow path (760), a pressure sensor (765), and a detection unit (767). The throttle valve (75) has an inlet and an outlet (755) for drive oil from the first hydraulic drive line (71). The throttle valve (75) receives the pressure of the drive oil when the pressure of the drive oil is increased to close the outlet (755), and opens the outlet (755) when the pressure of the drive oil is not increased to exhaust the first hydraulic drive line (71). The lead-out flow path (760) leads the drive oil flowing out from the outlet (755) of the throttle valve (75). The pressure sensor (765) measures the pressure of the drive oil flowing out of the outlet (755) in the lead-out flow path (760). A detection unit (767) detects an abnormality in the gas content in the first hydraulic drive line (71) on the basis of the measurement value of the pressure sensor (765).

Description

Monitoring system

Technical Field

The present invention relates to a monitoring system that monitors an oil pressure drive line of a diesel engine.

Background

Conventionally, a diesel engine for a ship is provided with an exhaust port for discharging gas burned in a combustion chamber and an exhaust valve for opening and closing the exhaust port, and the operation of the exhaust valve driven by hydraulic pressure is monitored by a stroke sensor (stroke sensor). However, the oil pressure drive line that drives the exhaust valve is not typically monitored.

On the other hand, japanese patent No. 5835004 (document 1) proposes the following technique: in a gasoline engine for a vehicle, the pressure of oil supplied to a hydraulically driven component is detected, and when the fluctuation width of the pressure pulsation of the oil is smaller than a threshold value, it is estimated that the oil pump is in an intake state and the bubble fraction of the oil is increased. Further, japanese patent No. 4730100 (document 2) proposes the following technique: in a brake control device for a vehicle, the pressure of a working fluid supplied to a wheel cylinder (wheel cylinder) for applying a braking force to a wheel is detected, and the presence or absence of air mixing into the working fluid and the air mixing amount are determined based on the pressure variation of the working fluid.

In the monitoring devices of

documents

1 and 2, pressure fluctuations of the drive oil pumped from the pump and supplied to the drive target (for example, a wheel cylinder) are measured in the hydraulic drive line, and the mixing of air into the drive oil is detected based on the measurement results. However, since the flow rate of the drive oil supplied to the drive target is relatively large and the pressure is also relatively high, it is difficult to exhibit the influence of air entrainment in the drive oil, and it is difficult to accurately detect air entrainment in the monitoring device. Further, if the amount of air mixed increases to a state where the monitoring device can detect air mixing, there is a possibility that an abnormality may have occurred during operation of the driving target.

Disclosure of Invention

The invention aims to provide a monitoring system for monitoring a hydraulic drive line of a diesel engine, and aims to realize early detection of gas content abnormality in the hydraulic drive line.

A monitoring system according to a preferred aspect of the present invention includes: a throttle (throttle valve) having an inlet and an outlet for the drive oil from the hydraulic drive line, the throttle valve being configured to receive the pressure of the drive oil to close the outlet when the pressure of the drive oil is increased and to open the outlet when the pressure of the drive oil is not increased to exhaust the hydraulic drive line; a lead-out flow path that leads the drive oil flowing out from the outlet of the throttle valve; a pressure sensor that measures a pressure of the drive oil flowing out of the outlet in the lead-out flow path; and a detection unit that detects an abnormality in the gas content in the hydraulic drive line based on a measurement value of the pressure sensor.

According to the present invention, it is possible to early detect an abnormality in the gas content in the hydraulic drive line.

Preferably, the detection unit detects an abnormality in the gas content in the hydraulic drive line by comparing a measurement value of the pressure sensor with a reference value in a normal state with respect to a peak pressure of the drive oil immediately before the outlet of the throttle valve is closed.

More preferably, the detection unit detects that the gas content in the hydraulic drive line is abnormal when the peak pressure continuously decreases in a plurality of cycles.

Preferably, the measurement by the pressure sensor is performed based on a drive control signal for a drive target of the hydraulic drive line.

Preferably, the discharge flow path is provided independently of a drain line through which the drive oil discharged from a portion of the hydraulic drive line other than the throttle valve flows.

Preferably, the detection unit acquires a gas content in the hydraulic drive line based on a measurement value of the pressure sensor.

More preferably, the monitoring system further includes an alarm unit configured to give an alarm when a gas content in the hydraulic drive line acquired by the detection unit is greater than a predetermined threshold value.

Preferably, the driving object of the oil pressure driving line includes an exhaust valve of a diesel engine.

The above and other objects, features, aspects and advantages will become apparent from the following detailed description of the present invention, which is to be read in connection with the accompanying drawings.

Drawings

Fig. 1 is a diagram showing a configuration of a diesel engine according to an embodiment.

Fig. 2 is a sectional view showing the vicinity of the exhaust valve cylinder.

Fig. 3 is a sectional view showing a throttle valve.

Fig. 4 is a sectional view showing a throttle valve.

Fig. 5 is a diagram showing a reference variation in the pressure of the drive oil.

Fig. 6 is a diagram showing a configuration of the monitoring unit.

Fig. 7 is a diagram showing pressure fluctuations of the drive oil in an abnormal state.

Fig. 8 is a diagram showing pressure fluctuations of the drive oil in an abnormal state.

[ description of symbols ]

1: diesel engine

25: air exhaust valve

71: first oil pressure driving pipeline

75: throttle valve

76: monitoring system

754: (of throttling valve) inlet

755: (of a throttle valve) outlet

760: lead-out flow path

765: pressure sensor

767: detection part

768: alarm part

Detailed Description

Fig. 1 is a diagram showing a configuration of a diesel engine 1 according to an embodiment of the present invention. The diesel engine 1 illustrated in fig. 1 is a two-stroke engine used as a main engine of a ship. Fig. 1 shows a part of the diesel engine 1 in cross section.

The diesel engine 1 includes: the engine includes a cylinder 2, a piston 3, an exhaust valve 25, an exhaust path 241, an exhaust pipe 42, a supercharger 5, an air cooler 43, a scavenging pipe 41, a scavenging chamber 231, a fuel supply mechanism 6, and a hydraulic drive mechanism 7.

The cylinder 2 includes a cylinder liner 21 and a cylinder head 22. The cylinder liner 21 is a substantially cylindrical member. The cylinder head 22 is a substantially cylindrical member having a cover attached to the upper portion of the cylinder liner 21. The cylinder head 22 covers an upper opening of the cylinder liner 21. A plurality of through holes are circumferentially provided near the lower end portion of the cylinder liner 21. The plurality of through holes are scavenging ports 23 for supplying scavenging gas, which will be described later, into the cylinder 2. A scavenging chamber 231 is disposed around the scavenging port 23. The scavenging port 23 is connected to the scavenging pipe 41 via a scavenging chamber 231.

An exhaust port 24 for discharging gas in the cylinder 2 to the outside of the cylinder 2 is provided at an upper end portion of the cylinder head 22. The shape of the exhaust port 24 in plan view (i.e., the shape viewed from the top-bottom direction in fig. 1) is substantially circular. Further, the vertical direction in fig. 1 does not necessarily coincide with the direction of gravity.

The exhaust valve 25 is disposed at a position overlapping the exhaust port 24 in the vertical direction, and opens and closes the exhaust port 24. The exhaust valve 25 includes a valve body 251 and a valve stem 252. The valve body 251 is a substantially conical portion located below the exhaust port 24. The valve body 251 has a larger diameter in plan view than the exhaust port 24 in plan view. The valve rod 252 is a substantially columnar portion extending upward from the upper end of the valve body 251. The upper end portion of the valve rod 252 is accommodated in an exhaust valve hydraulic cylinder 253 provided above the cylinder 2, and is supported to be movable in the vertical direction.

The exhaust valve 25 is moved in the vertical direction by the hydraulic drive mechanism 7. As shown by the solid line in fig. 1, in a state where the valve body 251 of the exhaust valve 25 is spaced downward from the exhaust port 24, the exhaust port 24 is opened, and the gas in the cylinder 2 is discharged to the outside of the cylinder 2 through the exhaust port 24. On the other hand, in a state where the valve body 251 is positioned at the position indicated by the two-dot chain line in fig. 1, the valve body 251 contacts the peripheral edge portion of the exhaust port 24 to close the exhaust port 24, and therefore, the gas in the cylinder 2 is not discharged from the exhaust port 24. In the following description, the position of the exhaust valve 25 indicated by the solid line in fig. 1 is referred to as "open position", and the position of the exhaust valve 25 indicated by the two-dot chain line is referred to as "closed position". The exhaust valve 25 is movable in the vertical direction between an open position and a closed position above the open position.

In a state where the exhaust valve 25 is located at the open position, gas discharged from the exhaust port 24 to the outside of the cylinder 2 (hereinafter referred to as "exhaust gas") is guided to the exhaust pipe 42 via the exhaust path 241. In an actual diesel engine 1, a plurality of cylinders 2 are provided in parallel, and one scavenging pipe 41 and one exhaust pipe 42 are connected to the plurality of cylinders 2.

The exhaust gas in the exhaust pipe 42 is sent to the supercharger 5 as a turbocharger, and is supplied to the turbine 51 of the supercharger 5. The exhaust gas used for rotation of the turbine 51 is discharged to the outside of the diesel engine 1 via a reduction catalyst or the like (not shown) for reducing Nitrogen Oxides (NOX). In the compressor 52 of the supercharger 5, intake air (air) taken in from the outside of the diesel engine 1 is pressurized by the rotational force generated by the turbine 51. The pressurized air (hereinafter referred to as "scavenging") is cooled by a refrigerant such as seawater in the air cooler 43, and then supplied into the scavenging pipe 41. In this way, the supercharger 5 pressurizes intake air with exhaust gas to generate scavenging gas.

The piston 3 is movable in the cylinder 2 in the up-down direction in fig. 1. In fig. 1, the position of the piston 3 indicated by the two-dot chain line is the top dead center, and the position of the piston 3 indicated by the solid line is the bottom dead center. The piston 3 includes a piston head 31 and a piston rod 32. The piston head 31 is a thick, substantially disk-shaped portion inserted into the cylinder liner 21. The piston rod 32 is a substantially cylindrical portion having an upper end connected to the lower surface of the piston head 31. The lower end of the piston rod 32 is connected to a crank mechanism, not shown. In the diesel engine 1 exemplified in fig. 1, a space surrounded by the cylinder liner 21, the cylinder head 22, the exhaust valve 25, and the upper surface of the piston head 31 is a combustion chamber 20 for combustion gas.

The fuel supply mechanism 6 includes a fuel injection portion 61 and a fuel supply pump 62. The fuel injection portion 61 is a nozzle attached to the cylinder head 22 with its tip end portion directed toward the combustion chamber 20. The fuel supply pump 62 is connected to a fuel tank (not shown) via a fuel pipe, and sends fuel in the fuel tank to the fuel injection portion 61. The fuel injection unit 61 injects the fuel supplied from the fuel supply pump 62 into the combustion chamber 20. The fuel supply pump 62 is also driven by the hydraulic drive mechanism 7.

Next, the operation of the diesel engine 1 will be described. In the diesel engine 1, when the piston 3 rises from the bottom dead center to be located near the top dead center, the exhaust valve 25 is located at the closed position, and the exhaust port 24 is closed. Therefore, the gas (scavenging gas, described later) in the combustion chamber 20 is compressed. Then, fuel is injected from the fuel injection portion 61 into the combustion chamber 20, the vaporized fuel ignites by itself, and the gas in the combustion chamber 20 is combusted (i.e., exploded). Thereby, the piston 3 is pressed downward and moves toward the bottom dead center. The gas in the combustion chamber 20 is not necessarily self-ignited, and the gas in the combustion chamber 20 may be ignited by using a spark plug or the like.

After the combustion of the gas in the combustion chamber 20, the exhaust valve 25 descends from the closed position to the open position before the piston 3 reaches the bottom dead center, and the exhaust port 24 is opened. Thereby, the discharge of the burned gas in the combustion chamber 20 is started. As described above, the gas discharged from the combustion chamber 20 (i.e., the exhaust gas) is supplied to the turbine 51 of the supercharger 5 via the exhaust path 241 and the exhaust pipe 42, and is discharged to the outside of the diesel engine 1 through the reduction catalyst and the like.

When the piston 3 is lowered near the bottom dead center and the upper surface of the piston head 31 moves to a lower side than the scavenging port 23, the scavenging port 23 is opened, and the combustion chamber 20 and the scavenging chamber 231 communicate with each other via the scavenging port 23. Thereby, the scavenging gas in the scavenging chamber 231 is supplied into the combustion chamber 20.

The piston 3 is turned to rise after reaching the bottom dead center. The upper surface of the piston head 31 rises to the upper side than the scavenging port 23, whereby the scavenging port 23 is closed, thereby stopping the supply of scavenging gas into the combustion chamber 20. Then, the exhaust port 24 is closed by an exhaust valve 25, and the combustion chamber 20 is closed. The scavenging gas in the combustion chamber 20 is compressed by the piston 3 further rising. When the piston 3 reaches the vicinity of the top dead center, fuel is injected from the fuel injection portion 61 into the combustion chamber 20, and the combustion occurs in the combustion chamber 20. In the diesel engine 1, the operation is repeated.

Next, the details of the hydraulic drive mechanism 7 will be described. The hydraulic drive mechanism 7 includes a hydraulic drive line 71, a hydraulic drive line 72, a drive oil tank 73, a drive oil pump 74, and a drive oil supply section 77. The drive oil tank 73 stores drive oil. The drive oil pump 74 sends the drive oil in the drive oil tank 73 to the hydraulic drive line 71 and the hydraulic drive line 72. The hydraulic drive line 71 is connected to the exhaust valve cylinder 253 and drives the exhaust valve 25. The oil pressure drive line 72 is connected to the fuel supply mechanism 6, and drives the fuel supply pump 62. That is, the hydraulic drive line to which the exhaust valve 25 is driven is the "first hydraulic drive line 71". The hydraulic drive line to which the fuel supply pump 62 is driven is referred to as a "second hydraulic drive line 72". The drive oil supply unit 77 supplies drive oil to the drive oil tank 73. The drive oil supply unit 77 continuously measures the amount of drive oil stored in the drive oil tank 73, for example, and supplies the drive oil to the drive oil tank 73 when the amount of drive oil is less than a predetermined amount.

Fig. 2 is an enlarged cross-sectional view of the vicinity of the exhaust valve cylinder 253. Fig. 2 also shows the structure of the first hydraulic drive line 71. The first hydraulic drive line 71 includes a pipe 711, a valve 712, a flow passage 713, a hydraulic piston 714, a spring 715, and a throttle valve 75. The flow passage 713 is formed in the exhaust valve cylinder 253. The hydraulic piston 714, the spring 715, and the throttle valve 75 are housed inside the exhaust valve cylinder 253. A monitoring system 76 that monitors the first oil pressure drive line 71 is provided near the throttle valve 75.

The pipe 711 guides the drive oil sent from the drive oil pump 74 (see fig. 1) to the flow path 713. In fig. 2, the drive oil flowing through the flow path 713 and the like is also indicated by parallel oblique lines. The valve 712 is provided in the pipe 711 and controls supply of the drive oil to the flow passage 713. The state of the drive oil of the first hydraulic drive line 71 is switched between a pressure-increasing state and a non-pressure-increasing state by opening and closing the valve 712. In fig. 2, the first oil pressure drive line 71 at the time of non-pressure increase is shown.

The flow passage 713 is connected to the upper end of the hydraulic piston 714 and the lower end of the throttle valve 75. The hydraulic piston 714 is a substantially cylindrical member having a lid. A spring 715 is housed inside the hydraulic piston 714. The lower end of the spring 715 is in contact with the upper end surface of the valve stem 252 of the exhaust valve 25. The valve rod 252 is pressed against the spring 715 (i.e., upward) by an air piston 254 provided in the exhaust valve cylinder 253. The spring 715 is, for example, a coil spring. The spring 715 may be various elastic members other than a coil spring.

In the first hydraulic drive line 71 at the time of non-pressure increase, the valve stem 252, the hydraulic piston 714, and the spring 715 are pressed upward by the pressure of the air piston 254. The upper end of the hydraulic piston 714 is in contact with or close to the top cover of the exhaust valve hydraulic cylinder 253, and the exhaust valve 25 is closed. On the other hand, the spring 715 is pressed downward by the pressure of the pressurized drive oil received in the first hydraulic drive line 71 at the time of pressure increase. Thereby, the spring 715 and the valve rod 252 move downward against the pressure of the air piston 254, and the exhaust valve 25 is opened. When the pressure of the drive oil is increased in the first hydraulic drive line 71 and the drive oil returns to the non-increased pressure state, the valve rod 252 and the spring 715 are pushed up by the pressure of the air piston 254, and the exhaust valve 25 is closed.

The drive oil in the exhaust valve hydraulic cylinder 253 flows out through a plurality of orifices provided in the side wall of the exhaust valve hydraulic cylinder 253, is received by the drive oil reservoir 255 provided below the air piston 254, and is temporarily stored therein. The drive oil stored in the drive oil reservoir 255 flows downward along the outer surface of the valve rod 252 from the gap between the drive oil reservoir 255 and the valve rod 252. Thereby, frictional resistance is reduced at a sliding portion of the exhaust valve 25 (for example, a portion 257 between the support portion supporting the valve stem 252 and the valve stem 252), and the vertical movement of the exhaust valve 25 is smoothly performed. In addition, the sliding portion is hermetically sealed.

The drive oil flowing down from the drive oil reservoir 255 is temporarily stored as drain oil in a crankcase (not shown) located below the cylinder 2. The drain oil is pumped up by the circulation pump, purified by a filter or the like, and returned to the drive oil tank 73 to be reused. In the following description, the flow path of the drive oil from the exhaust valve hydraulic cylinder 253 to the crankcase is referred to as a "drain line".

The throttle valve 75 is a mechanical valve that exhausts the drive oil of the first hydraulic drive line 71. The throttle valve 75 is disposed above the hydraulic piston 714 in the first hydraulic drive line 71, for example. The upper end portion of the throttle valve 75 is disposed inside a buffer portion 716 formed in the exhaust valve cylinder 253. The buffer 716 is a relatively small space that temporarily stores the drive oil flowing out of the flow path 713 via the throttle valve 75.

Fig. 3 and 4 are enlarged cross-sectional views of the throttle valve 75. Fig. 3 shows the throttle valve 75 in an open state when the first hydraulic drive line 71 is not pressurized. Fig. 4 shows the throttle valve 75 in a closed state when the pressure of the first hydraulic drive line 71 is increased. The throttle valve 75 is a substantially cylindrical member centered on the center axis J1. In the example shown in fig. 3, the center axis J1 is oriented in a substantially vertical direction. The length of the throttle valve 75 in the vertical direction is, for example, 4.3cm to 5.5 cm.

The throttle valve 75 includes an outer cylinder portion 751, an inner cylinder portion 752, and an elastic member 753. The outer cylinder portion 751 and the inner cylinder portion 752 are each a substantially cylindrical member extending in a substantially vertical direction about a central axis J1. The outer tube 751 has a lower opening 754 and an upper opening 755 at the lower end and the upper end, respectively. The inner tube portion 752 is disposed inside the outer tube portion 751 between the lower opening 754 and the upper opening 755. The inner tube portion 752 is movable in the vertical direction between the position shown in fig. 3 and the position shown in fig. 4. The elastic member 753 is disposed between the outer surface of the inner cylinder 752 and the inner surface of the outer cylinder 751 in a state compressed in the vertical direction. The elastic member 753 presses the inner tube portion 752 downward. In the example shown in fig. 3 and 4, the elastic member 753 is a coil spring.

A plurality of orifices 756 each penetrating the inner cylinder portion 752 are provided on the upper side surface of the inner cylinder portion 752. In the throttle valve 75, the inner space of the inner tube 752 and the inner space of the outer tube 751 communicate with each other through the plurality of orifices 756. In the example shown in fig. 3 and 4, the four orifices 756 are arranged at substantially equal angular intervals in the circumferential direction around the central axis J1. The number and arrangement of orifices 756 may be changed as appropriate.

In the first hydraulic drive line 71 shown in fig. 3, during non-pressure-raising, the drive oil in the flow path 713 (see fig. 2) flows into the throttle valve 75 through the lower opening 754 and flows upward in the internal space of the inner tube portion 752. The drive oil flows out from the internal space of the inner tube 752 to the space between the upper outer surface of the inner tube 752 and the inner surface of the outer tube 751 through the plurality of orifices 756, and flows out to the outside of the throttle valve 75 through the upper opening 755. The gas in the drive oil of the first hydraulic drive line 71 is discharged to the outside of the first hydraulic drive line 71 together with the drive oil that flows out to the outside from the throttle valve 75. In the throttle valve 75, the lower opening 754 is an inlet of the drive oil, and the upper opening 755 is an outlet of the drive oil. In the following description, the lower opening 754 and the upper opening 755 of the throttle valve 75 are referred to as an "inlet 754" and an "outlet 755", respectively.

On the other hand, in the first hydraulic drive line 71 at the time of pressure increase shown in fig. 4, the inner tube 752 is pressed upward by the pressure of the pressurized drive oil. Thereby, the inner tube portion 752 moves upward while compressing the elastic member 753, and the upper end outer surface of the inner tube portion 752 comes into contact with the inner surface of the outer tube portion 751. As a result, the outlet 755 is closed by the inner tube 752, and the flow of the drive oil out of the throttle valve 75 is stopped. When the pressure of the drive oil is increased and the throttle valve 75 returns to the non-pressure-increased state, the inner tube 752 is pushed down by the restoring force of the elastic member 753, and the outlet 755 is opened.

As shown in fig. 2, the monitoring system 76 includes the throttle valve 75, a sensor portion 761, a monitoring portion 762, and an outflow line 769. The sensor portion 761 includes a mounting portion 764 and a pressure sensor 765. The mounting portion 764 is attached to the outer wall of the exhaust valve cylinder 253 on the side of the buffer portion 716. A flow path through which the drive oil flowing out from the buffer portion 716 to the outside of the exhaust valve cylinder 253 flows is formed inside the mounting portion 764. The pressure sensor 765 is disposed below the flow path of the mounting portion 764, and measures the pressure of the drive oil flowing through the flow path (i.e., the pressure of the drive oil flowing out of the outlet 755 of the throttle valve 75) at the lower portion of the flow path. The pressure sensor 765 is preferably disposed at a lower side than the outlet 755 of the throttle valve 75.

The flow path inside the mounting portion 764 is connected to one end of the outflow line 769. The outflow line 769 is a pipe extending upward to a position above the outlet 755 of the throttle valve 75 and then downward outside the exhaust valve cylinder 253. The other end portion of the outflow line 769 is connected to the exhaust valve hydraulic cylinder 253, and communicates with the internal space of the exhaust valve hydraulic cylinder 253 above the drive oil reservoir 255. The outflow line 769 may be provided inside the exhaust valve cylinder 253.

The outflow line 769 returns the drive oil flowing out of the buffer 716 to the outside of the exhaust valve hydraulic cylinder 253 to the inside of the exhaust valve hydraulic cylinder 253. The drive oil introduced into the exhaust valve hydraulic cylinder 253 through the outflow line 769 is received by the drive oil reservoir 255 and temporarily stored therein. As described above, the drive oil stored in the drive oil reservoir 255 flows downward along the outer surface of the valve rod 252 from the gap between the drive oil reservoir 255 and the valve rod 252. This reduces frictional resistance at the sliding portion of the exhaust valve 25, and allows the exhaust valve 25 to smoothly move in the vertical direction. In addition, the sliding portion is hermetically sealed.

When the flow passage inside the buffer portion 716 and the mounting portion 764 and the outflow line 769 are collectively referred to as "the lead-out flow passage 760", the lead-out flow passage 760 is a flow passage for guiding the drive oil flowing out from the outlet 755 of the throttle valve 75 to the sliding portion of the exhaust valve 25. As described above, the drive oil guided to the sliding portion is used as the lubricating oil for reducing friction. The lead-out flow path 760 does not necessarily lead all of the drive oil flowing out of the throttle valve 75 to the sliding portion of the exhaust valve 25. The lead-out flow passage 760 is preferably a sliding portion that guides at least a part of the drive oil flowing out of the throttle valve 75 to the exhaust valve 25. The lead-out flow path 760 is provided separately from the drain line through which the drive oil discharged from the first hydraulic drive line 71 other than the throttle valve 75 flows.

As described above, the pressure sensor 765 is attached to the flow path inside the attachment portion 764 as illustrated in fig. 2, but the pressure sensor 765 may be attached to any portion of the lead-out flow path 760. For example, a pressure sensor 765 may be installed at the buffer portion 716 to measure the pressure of the driving oil in the buffer portion 716. Alternatively, a pressure sensor 765 may be installed at the outflow line 769 to measure the pressure of the driving oil in the outflow line 769. That is, the pressure sensor 765 measures the pressure of the drive oil flowing out of the outlet 755 of the throttle valve 75 in the lead-out flow path 760. The output from the pressure sensor 765 (i.e., the measured value of the pressure of the drive oil) is sent to the monitoring unit 762.

Fig. 5 is a diagram showing an example of the pressure of the drive oil flowing out from the throttle valve 75 to the lead-out flow passage 760. Fig. 5 shows an output from the pressure sensor 765 in a case where the gas content of the drive oil supplied from the first hydraulic drive line 71 to the exhaust valve 25 is within a normal range (hereinafter, also referred to as a "normal state"). In the following description, the periodic variation in the pressure of the drive oil flowing out from the outlet 755 of the throttle valve 75 in the normal state is referred to as "reference variation".

The normal state is a state in which the ratio of the gas contained in the drive oil supplied to the exhaust valve 25 to the drive oil is equal to or less than a predetermined threshold value. In other words, the normal state is a state in which the proportion of the space occupied by the gas in the internal space of the first hydraulic drive line 71 (i.e., the gas occupancy rate) is equal to or less than a predetermined threshold value. Further, in the normal state, the operation of the exhaust valve 25 is also normal.

In the following description, a state in which the gas content is greater than the normal range is also referred to as an "abnormal state". The cause of the abnormal state is, for example: the amount of oil in the first hydraulic drive line 71 is insufficient due to a large amount of air mixed with the drive oil supplied to the exhaust valve 25, or due to a shortage of the drive oil in the drive oil tank 73, or the like. Even in the abnormal state, the operation of the exhaust valve 25 is not necessarily abnormal. For example, even when the gas content of the drive oil supplied to the exhaust valve 25 is slightly larger than the normal range, the operation of the exhaust valve 25 is not abnormal when the state is maintained close to the normal range. On the other hand, when the gas content of the drive oil supplied to the exhaust valve 25 continues to increase and exceeds the normal range, the exhaust valve 25 may be shifted from the normal operation to the abnormal operation.

As described above, since the throttle valve 75 is a valve for discharging the drive oil from the first hydraulic drive line 71, the gas content of the drive oil flowing out from the outlet 755 of the throttle valve 75 is greater than the gas content of the drive oil supplied to the exhaust valve 25. Further, when the gas content of the drive oil supplied to the exhaust valve 25 increases, the gas content of the drive oil flowing out of the outlet 755 of the throttle valve 75 also increases. The pressure of the drive oil flowing out of the outlet 755 of the throttle valve 75 is much lower than the pressure of the drive oil supplied to the exhaust valve 25. For example, the pressure of the drive oil flowing out of the throttle valve 75 is about one tenth of the pressure of the drive oil supplied to the exhaust valve 25.

The horizontal axis in fig. 5 represents the crank angle (°) of the crank mechanism connected to the piston 3. The vertical axis in fig. 5 represents the pressure (bar) of the drive oil flowing out of the outlet 755 of the throttle valve 75. The curve indicated by reference numeral 90 in fig. 5 is a reference variation in the pressure of the drive oil over one cycle (i.e., during a change in the crank angle from 0 ° to 360 °). In the range of 0 ° to about 120 ° in crank angle, the first oil pressure drive line 71 is in a non-pressurized state, and the drive oil flows out from the outlet 755 of the throttle valve 75 in an open state. Therefore, the pressure of the drive oil measured by the pressure sensor 765 is substantially the same as and relatively low as the pressure of the drive oil at the time of non-pressure increase.

When the crank angle becomes about 120 °, the first hydraulic drive line 71 is in a pressure-increasing state, and the throttle valve 75 is shifted from the open state to the closed state. At this time, the boosted drive oil flows out from the outlet 755 of the throttle valve 75 in a short time before the throttle valve 75 is closed. Therefore, when the crank angle is about 120 °, the pressure of the drive oil measured by the pressure sensor 765 increases instantaneously, and a peak of the pressure in the reference fluctuation occurs.

In the range of about 120 ° to about 240 ° in crank angle, the first oil pressure drive line 71 is in a pressure-increasing state, and the throttle valve 75 is in a closed state, so that the pressure of the drive oil measured by the pressure sensor 765 is relatively low. In the range of about 240 ° to 360 ° in crank angle, the first hydraulic drive line 71 is in a non-pressure-increasing state, and the throttle valve 75 is in an open state, so the pressure of the drive oil measured by the pressure sensor 765 is relatively low. The pressure fluctuation of the drive oil in the range of about 300 ° to 360 ° in crank angle is caused by the supply of the drive oil by the drive oil supply section 77 and the like, and is not caused by the opening and closing of the throttle valve 75.

The reference variation shown in fig. 5 is obtained by measuring the pressure of the drive oil by the pressure sensor 765, for example, in a state where it is confirmed that the gas content of the drive oil supplied to the exhaust valve 25 is within a normal range. Alternatively, the reference variation may be obtained by simulation or the like.

The monitoring unit 762 shown in fig. 2 is, for example, a general computer. As shown in fig. 6, the computer includes a processor 81, a memory 82, an input/output unit 83, and a bus 84. The bus 84 is a signal circuit connecting the processor 81, the memory 82, and the input/output unit 83. The memory 82 stores programs and various information. The processor 81 executes various processes (for example, numerical calculation and image processing) in accordance with a program or the like stored in the memory 82 while using the memory 82 or the like. The input/output unit 83 includes a keyboard 85 and a mouse 86 for receiving input from an operator, and a display 87 for displaying output from the processor 81.

As shown in fig. 2, the monitoring unit 762 includes a storage unit 766, a detection unit 767, and an alarm unit 768. The storage 766 is mainly implemented by the memory 82 and stores various information. The detection unit 767 is realized mainly by the processor 81, and detects an abnormality in the gas content in the first hydraulic drive line 71 based on the information stored in the storage unit 766 and the output from the pressure sensor 765 (i.e., the measurement value of the pressure sensor 765). The alarm unit 768 gives an alarm to a crew or the like when the gas content abnormality is detected. The alarm unit 768 displays a warning on the display 87, or sounds an alarm buzzer, for example.

Specifically, the storage 766 stores a reference variation in the pressure of the drive oil flowing out of the outlet 755 of the throttle valve 75. The storage 766 may store the entire reference variation, or may store a part of the value of the reference variation. In the present embodiment, the peak pressure (i.e., the maximum value of the reference fluctuation) at the crank angle of about 120 ° in the reference fluctuation is stored in advance as the reference value in the normal state.

In the first hydraulic drive line 71, if the gas content of the drive oil supplied to the exhaust valve 25 is greater than the normal range, the gas content of the drive oil flowing out from the outlet of the throttle valve 75 to the lead-out flow passage 760 also increases. Therefore, the apparent bulk modulus of the drive oil flowing through the lead-out flow passage 760 is reduced, and as shown in fig. 7 and 8, the pressure pulsation of the drive oil flowing out from the throttle valve 75 to the lead-out flow passage 760 is also reduced. The graphs denoted by

reference numerals

91 and 92 in fig. 7 and 8 show the periodic variation in the pressure of the drive oil that flows out from the throttle valve 75 to the lead-out flow passage 760 in the abnormal state. In fig. 7 and 8, the reference fluctuation shown in fig. 5 is also shown by a broken line. The gas content of the drive oil is higher in the state shown in fig. 8 than in the state shown in fig. 7. In the state of fig. 7, no abnormality occurs in the operation of the exhaust valve 25, but in the state of fig. 8, an abnormality occurs in the operation of the exhaust valve 25.

The detection unit 767 compares the measurement value of the pressure sensor 765 with the reference value in the normal state stored in the storage unit 766 for the peak pressure at the crank angle of about 120 ° (i.e., the peak pressure of the drive oil immediately before the closing of the outlet 755 of the throttle valve 75). Then, when the difference between the reference value and the measurement value of the pressure sensor 765 is larger than a predetermined threshold value, it is determined that an abnormality in the gas content in the first hydraulic drive line 71 (that is, an abnormality in which the gas content becomes larger than the normal range) has occurred. When the gas content abnormality is detected by the detection unit 767, the gas content abnormality is notified to a crew or the like by the alarm unit 768.

The pressure sensor 765 may continuously measure the pressure of the drive oil in the lead-out flow passage 760, or may intermittently measure the pressure of the drive oil in the lead-out flow passage 760 at a predetermined timing. For example, in the case where the gas content abnormality is detected based on the peak pressure when the crank angle is about 120 ° as described above, the pressure sensor 765 may measure only the pressure of the driving oil when the crank angle is about 120 °. In this case, the pressure measurement by the pressure sensor 765 is preferably performed based on a drive control signal for the exhaust valve 25 that is issued in synchronization with the crank angle.

The detection portion 767 can acquire the value of the gas content of the drive oil in the first hydraulic drive line 71 based on the measurement value of the pressure sensor 765. For example, a table, a numerical expression, or the like indicating a relationship between the peak pressure of the drive oil flowing out from the outlet 755 of the throttle valve 75 and the gas content of the drive oil in the first hydraulic drive line 71 is stored in advance in the storage 766, and the gas content of the drive oil in the first hydraulic drive line 71 is obtained based on the measurement value of the pressure sensor 765 and the table, the numerical expression, or the like. The detection unit 767 may determine the gas content of the drive oil in the first hydraulic drive line 71 based on the difference between the measurement value of the pressure sensor 765 and the reference value in the normal state stored in the storage unit 766.

In the case where the gas content is acquired as described above, the alarm unit 768 may issue an alarm when the gas content of the drive oil in the first hydraulic drive line 71 acquired by the detection unit 767 is greater than a predetermined threshold value. For example, the alarm unit 768 generates a first alarm when the gas content rate abnormality is detected by the detection unit 767, and generates a second alarm when the gas content rate acquired by the detection unit 767 increases to a level near a level at which the operation abnormality of the exhaust valve 25 is caused (i.e., when the gas content rate becomes larger than the threshold value).

The detection unit 767 may detect the gas content abnormality in the first hydraulic drive line 71, not necessarily when the difference between the reference value in the normal state and the measurement value of the pressure sensor 765 is larger than a predetermined threshold value, but when the difference between the reference value in the normal state and the measurement value of the pressure sensor 765 is larger than a predetermined threshold value and the measurement value of the pressure sensor 765 continuously decreases in a plurality of cycles with respect to the peak pressure. This prevents sudden gas mixture that immediately returns to normal from being detected as a gas content abnormality, and thus it is possible to accurately detect a major abnormality such as a gradual increase in the gas content in the first hydraulic drive line 71. The detection of the gas content abnormality by the detector 767 is not limited to the case where the measured values of the peak pressure continuously decrease in a plurality of cycles, and all of them may be detected as the gas content abnormality when the peak pressure is smaller than the reference value by a certain degree or more.

As explained above, the monitoring system 76 monitors the oil pressure drive line (i.e., the first oil pressure drive line 71) of the diesel engine 1. The monitoring system 76 includes the throttle valve 75, the lead-out flow path 760, the pressure sensor 765, and the detection portion 767. The throttle valve 75 has an inlet 754 for drive oil from the first oil pressure drive line 71 and an outlet 755. The throttle valve 75 receives the pressure of the drive oil when the pressure of the drive oil is increased to close the outlet 755, and opens the outlet 755 when the pressure of the drive oil is not increased to exhaust the first hydraulic drive line 71. The lead-out flow path 760 leads the drive oil flowing out from the outlet 755 of the throttle valve 75. The pressure sensor 765 measures the pressure of the drive oil flowing out of the outlet 755 in the lead-out flow path 760. The detection unit 767 detects an abnormality in the gas content in the first hydraulic drive line 71 based on the measurement value of the pressure sensor 765.

As described above, since the throttle valve 75 is a valve that exhausts the drive oil of the first hydraulic drive line 71, the gas content of the drive oil flowing out of the outlet 755 of the throttle valve 75 is greater than the gas content of the drive oil supplied to the drive target (i.e., the exhaust valve 25) of the first hydraulic drive line 71. Further, the pressure of the drive oil flowing out of the throttle valve 75 is lower than the pressure of the drive oil supplied to the drive target. Therefore, when the gas content in the drive oil supplied to the drive target shifts from the normal state to the abnormal state, the apparent volume elastic coefficient of the drive oil flowing out of the throttle valve 75 is more greatly reduced than the drive oil supplied to the drive target, and the amplitude of the pressure fluctuation is also greatly reduced. In other words, as for the influence of the gas contained in the drive oil, the influence on the drive oil flowing out from the throttle valve 75 is larger than the influence on the drive oil supplied to the driving target.

Therefore, as described above, by measuring the pressure of the drive oil flowing out of the outlet 755 of the throttle valve 75, it is possible to realize early detection of an abnormality in the gas content rate in the first hydraulic drive line 71. In the diesel engine 1, if it is possible to detect an abnormality in the gas content in the first hydraulic drive line 71 before an operation abnormality of the drive target of the first hydraulic drive line 71 occurs, the operation abnormality of the drive target can be prevented in advance. As a result, the failure of the diesel engine 1 can be prevented.

As described above, the driving target of the first hydraulic drive line 71 preferably includes the exhaust valve 25 of the diesel engine 1. This can prevent or suppress an abnormal operation of the exhaust valve 25 that plays an important role in driving the diesel engine 1.

As described above, the detection unit 767 preferably detects that the gas content in the first hydraulic drive line 71 is abnormal by comparing the measurement value of the pressure sensor 765 with the reference value in the normal state with respect to the peak pressure of the drive oil immediately before the outlet 755 of the throttle valve 75 is closed. Accordingly, the difference between the pressure measurement value of the drive oil in the normal state and the pressure measurement value of the drive oil in the abnormal state is increased, and thus, the gas content abnormality in the first hydraulic drive line 71 can be accurately detected.

Preferably, the detector 767 detects that the gas content in the hydraulic drive line is abnormal when the peak pressure continuously decreases in a plurality of cycles. Thus, a major gas content abnormality, such as a gradual increase in the gas content in the first hydraulic drive line 71, can be accurately detected without detecting a single decrease in peak pressure (i.e., noise) due to sudden gas mixing as a gas content abnormality.

As described above, it is preferable that the measurement by the pressure sensor 765 is performed based on the drive control signal for the drive target of the first hydraulic drive line 71. Thus, in the periodic variation of the pressure of the drive oil in the derivation flow passage 760, the pressure at a predetermined timing (for example, the peak pressure of the drive oil immediately before the closing of the outlet 755 of the throttle valve 75) can be easily obtained.

As described above, the lead-out flow passage 760 is preferably provided separately from the drain line through which the drive oil discharged from the first hydraulic drive line 71 other than the throttle valve 75 flows. This prevents or reduces the influence of pressure fluctuations in the drive oil flowing out of the area other than the throttle valve 75, and allows the pressure of the drive oil flowing out of the throttle valve 75 to be measured with high accuracy. As a result, it is possible to accurately detect the gas content abnormality in the first hydraulic drive line 71.

As described above, the detection portion 767 preferably acquires the gas content in the first hydraulic drive line 71 based on the measurement value of the pressure sensor 765. This makes it possible to grasp the degree of abnormality (i.e., a slight abnormality or a major abnormality) in the gas content in the first hydraulic drive line 71. As a result, appropriate measures such as maintenance can be selected according to the degree of abnormality in the gas content.

Further preferably, the monitoring system 76 further includes an alarm unit 768 configured to give an alarm when the gas content in the first hydraulic drive line 71 acquired by the detection unit 767 is greater than a predetermined threshold value. Therefore, the crew member or the like can recognize the serious gas content abnormality having a high possibility of causing the operation abnormality of the driving target of the first hydraulic drive line 71 at an early stage.

Various modifications may be made to the monitoring system 76.

For example, in the detection unit 767, the measurement value and the reference value are compared with each other for the peak pressure of the drive oil immediately before the closing of the outlet 755 of the throttle valve 75, but the gas content abnormality in the first hydraulic drive line 71 may be detected by comparing the measurement value and the reference value for the pressure of the other portion in the pressure fluctuation (for example, the peak pressure at the crank angle of about 340 °).

The pressure measurement of the drive oil by the pressure sensor 765 is not necessarily performed based on the drive control signal for the drive target (i.e., the exhaust valve 25) of the first hydraulic drive line 71, and may be performed continuously and constantly, for example.

In the monitoring system 76, it is also possible to omit the outflow line 769, which is independent of the drain line, and to lead the drive oil flowing out of the outlet 755 of the throttle valve 75 directly to the drain line. The drive oil flowing out of the throttle valve 75 of the first hydraulic drive line 71 is not necessarily guided to the sliding portion of the exhaust valve 25 and is used as lubricating oil.

The detection unit 767 does not necessarily have to determine the gas content in the first hydraulic drive line 71. Note that the alarm unit 768 may always give an alarm when an abnormality in the gas content rate is detected, not based on the gas content rate. Further, the alarm portion 768 is not necessarily provided.

The throttle valve 75 is not limited to the above configuration, and may have various other configurations. For example, a so-called check valve may also be used as the throttle valve 75.

The hydraulic drive line monitored by the monitoring system 76 is not necessarily the first hydraulic drive line 71 for the exhaust valve 25, and may be a hydraulic drive line for driving another driving object. For example, the second oil pressure drive line 72 for driving the fuel supply pump 62 may be monitored by the monitoring system 76.

The diesel engine 1 provided with the monitoring system 76 is not limited to the two-stroke engine, and may be a four-stroke engine. The monitoring system 76 may be provided not only in a diesel engine used as a main engine of a ship but also in various diesel engines such as a power generation diesel engine and an automobile diesel engine.

The configurations of the above-described embodiment and the modifications may be appropriately combined as long as they are not contradictory to each other.

The invention has been depicted and described in detail, with the understanding that the present disclosure is to be considered an exemplification and is not intended to be limiting. Therefore, various modifications and forms are possible without departing from the scope of the present invention.

Claims

1. A monitoring system that monitors an oil pressure drive line of a diesel engine, the monitoring system comprising:

a throttle valve having an inlet and an outlet for the drive oil from the hydraulic drive line, the throttle valve being configured to receive the pressure of the drive oil to close the outlet when the pressure of the drive oil is increased and to open the outlet when the pressure of the drive oil is not increased to exhaust the hydraulic drive line;

a lead-out flow path that leads the drive oil flowing out from the outlet of the throttle valve;

a pressure sensor that measures a pressure of the drive oil flowing out of the outlet in the lead-out flow path; and

and a detection unit that detects an abnormality in the gas content in the hydraulic drive line based on a measurement value of the pressure sensor.

2. The monitoring system of claim 1,

the detection unit detects an abnormality in the gas content in the hydraulic drive line by comparing a measurement value of the pressure sensor with a reference value in a normal state with respect to a peak pressure of the drive oil immediately before the outlet of the throttle valve is closed.

3. The monitoring system of claim 2,

the detection unit detects that the gas content in the hydraulic drive line is abnormal when the peak pressure continuously decreases in a plurality of cycles.

4. The monitoring system of claim 1,

the measurement by the pressure sensor is performed based on a drive control signal for a drive target of the hydraulic drive line.

5. The monitoring system of claim 1,

the discharge flow path is provided independently of a drain line through which the drive oil discharged from a portion of the hydraulic drive line other than the throttle valve flows.

6. The monitoring system of claim 1,

the detection unit acquires a gas content in the hydraulic drive line based on a measurement value of the pressure sensor.

7. The monitoring system of claim 6,

the hydraulic drive system further includes an alarm unit that issues an alarm when the gas content in the hydraulic drive line acquired by the detection unit is greater than a predetermined threshold value.

8. The monitoring system of any one of claims 1 to 7,

the driving object of the oil pressure driving line includes an exhaust valve of a diesel engine.