TWI842876B - Monitoring system - Google Patents

Abstract

A monitoring system 76 includes a throttle valve 75, an outlet channel 760, a pressure sensor 765, and a detection unit 767. The throttle valve 75 has a hydraulic oil inlet and outlet 755 from a first hydraulic drive line 71. The throttle valve 75 closes the outlet 755 by receiving the pressure of the hydraulic oil when the pressure of the hydraulic oil is increased, and opens the outlet 755 to vent the first hydraulic drive line 71 when the pressure of the hydraulic oil is not increased. The outlet channel 760 guides the hydraulic oil flowing out of the outlet 755 of the throttle valve 75. The pressure sensor 765 measures the pressure of the hydraulic oil flowing out of the outlet 755 in the outlet channel 760. The detection unit 767 detects a gas content abnormality in the first hydraulic drive line 71 based on a measurement value of the pressure sensor 765. Thus, early detection of a gas content abnormality in the first hydraulic drive line 71 can be realized.

Description

Monitoring system

The present invention relates to a monitoring system for monitoring the oil pressure drive pipeline of a diesel engine.

Previously, marine diesel engines were equipped with an exhaust port for discharging the gas after combustion in the combustion chamber and an exhaust valve for opening and closing the exhaust port, and a stroke sensor was used to monitor the operation of the exhaust valve driven by hydraulic pressure. However, the hydraulic drive line that drives the exhaust valve is usually not monitored.

On the other hand, the following technology is proposed in Japanese Patent No. 5835004 (Document 1): In a gasoline engine for a vehicle, the pressure of the oil supplied to the hydraulic drive parts is detected, and when the fluctuation range of the oil pressure pulse is less than the critical value, it is inferred that the oil pump has become an air intake state and the oil bubble rate has increased. In addition, the following technology is proposed in Japanese Patent No. 4730100 (Document 2): In a brake control device for a vehicle, the pressure of the working fluid supplied to the wheel cylinder for applying braking force to the wheel is detected, and based on the pressure fluctuation of the working fluid, whether air is mixed into the working fluid and the amount of air mixed are determined.

In addition, in the monitoring devices of Documents 1 and 2, the pressure change of the driving oil pumped out from the pump and supplied to the driving object (such as the wheel cylinder) is measured in the hydraulic driving pipeline, and the mixing of air into the driving oil is detected based on the measurement result. However, the flow rate of the driving oil supplied to the driving object is relatively large and the pressure is also relatively high, so it is difficult to show the influence of the mixing of air into the driving oil, and it is difficult to detect the mixing of air with good accuracy in the monitoring device. In addition, if the mixing amount of air increases to a state where the mixing of air can be detected by the monitoring device, it is possible that an abnormality has occurred in the operation of the driving object.

The present invention is directed to a monitoring system for monitoring the hydraulic drive line of a diesel engine, and aims to achieve early detection of abnormal gas content in the hydraulic drive line.

A preferred form of the monitoring system of the present invention includes: a throttle valve having an inlet and an outlet for driving oil from a hydraulic driving pipeline, and the outlet is closed by the pressure of the driving oil when the driving oil is pressurized, and the outlet is opened to exhaust the hydraulic driving pipeline when the driving oil is not pressurized; a discharge flow path to guide the driving oil flowing out of the outlet of the throttle valve; a pressure sensor to measure the pressure of the driving oil flowing out of the outlet in the discharge flow path; and a detection unit to detect abnormal gas content in the hydraulic driving pipeline based on the measured value of the pressure sensor.

According to the present invention, early detection of abnormal gas content in the hydraulic drive pipeline can be achieved.

Preferably, the detection unit detects the abnormal gas content in the oil pressure drive pipeline by comparing the measured value of the pressure sensor with the reference value under normal conditions for the peak pressure of the drive oil just before the outlet of the throttle valve is closed.

It is more preferable that the detection unit detects that the gas content rate in the hydraulic drive pipeline is abnormal when the peak pressure decreases continuously in multiple cycles.

Preferably, the measurement using the pressure sensor is performed based on a drive control signal for a drive object of the hydraulic drive pipeline.

It is preferred that the outlet flow path is provided independently of the discharge line, and the discharge line is used for the flow of the drive oil discharged from a portion other than the throttle valve of the hydraulic drive line.

Preferably, the detection unit obtains the gas content rate in the hydraulic drive pipeline based on the measured value of the pressure sensor.

Preferably, the monitoring system further includes an alarm unit, which issues an alarm when the gas content in the hydraulic drive pipeline obtained by the detection unit is greater than a specified critical value.

Preferably, the driving object of the hydraulic drive pipeline includes the exhaust valve of a diesel engine.

The above-mentioned purpose and other purposes, features, forms and advantages are explained by the following detailed description of the invention with reference to the accompanying drawings.

1: Diesel engine

2: Cylinder

20: Combustion chamber

21: Cylinder liner

22: Cylinder head

23: Sweep vent

231 Sweeping chamber

24: Exhaust port

241: Exhaust path

25: Exhaust valve

251: Valve body

252: Valve stem

253: Exhaust valve hydraulic cylinder

254: Air piston

255: Drive oil storage unit

3: Piston

31: Piston head

32: Piston rod

41: Sweep the air pipe

42: Exhaust pipe

43: Air cooler

5: Supercharger

51: Turbine

52: Compressor

6: Fuel supply mechanism

61: Fuel injection unit

62: Fuel supply pump

7: Hydraulic drive mechanism

71: First hydraulic drive pipeline (hydraulic drive pipeline)

711: Piping

712: Valve

713: Flow path

714: Hydraulic piston

715: Spring

716: Buffer Department

72: Hydraulic drive pipeline

73: Driving fuel tank

74: Driving oil pump

75:Throttle valve

751: Outer tube

752: Inner tube

753: Elastic components

754: (throttle valve) inlet lower opening

755: (throttle valve) outlet upper opening

756:Throttle hole

76: Monitoring system

760: Outflow path

761: Sensor Department

762: Surveillance Department

764: Installation Department

765: Pressure sensor

766: Storage Department

767: Testing Department

768: Police Department

769: Outflow pipeline

77: Drive oil supply department

81:Processor

82:Memory

83: Input and output department

84:Bus

85:Keyboard

86: Mouse

87: Display

J1: Center axis

FIG1 is a diagram showing the structure of a diesel engine in an implementation form.

Figure 2 is a cross-sectional view showing the vicinity of the exhaust valve hydraulic cylinder.

Figure 3 is a cross-sectional view of a throttle valve.

Figure 4 is a cross-sectional view showing a throttle valve.

Figure 5 is a graph showing the baseline variation of the driving oil pressure.

FIG6 is a diagram showing the structure of the monitoring unit.

Figure 7 is a graph showing the pressure change of the driving oil under abnormal conditions.

Figure 8 is a graph showing the pressure change of the driving oil under abnormal conditions.

FIG. 1 is a diagram showing the structure of a diesel engine 1 of an embodiment of the present invention. The diesel engine 1 shown in FIG. 1 is a two-stroke engine used as a main engine of a ship. In FIG. 1 , a part of the structure of the diesel engine 1 is shown in cross section.

The diesel engine 1 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 sweeping pipe 41, a sweeping chamber 231, a fuel supply mechanism 6, and a hydraulic drive mechanism 7.

The cylinder 2 includes a cylinder liner 21 and a cylinder cover 22. The cylinder liner 21 is a roughly cylindrical component. The cylinder cover 22 is a roughly covered cylindrical component installed on the upper part of the cylinder liner 21. The cylinder cover 22 covers the upper opening of the cylinder liner 21. Near the lower end of the cylinder liner 21, a plurality of through holes are provided in a circumferential shape. The plurality of through holes are scavenging ports 23 for supplying scavenging air described later into the cylinder 2. A scavenging chamber 231 is arranged around the scavenging port 23. The scavenging port 23 is connected to the scavenging pipe 41 via the scavenging chamber 231.

An exhaust port 24 is provided at the upper end of the cylinder head 22 to discharge the gas in the cylinder 2 to the outside of the cylinder 2. The shape of the exhaust port 24 when viewed from above (i.e., the shape viewed from the up and down direction in Figure 1) is roughly circular. Furthermore, the up and down direction in Figure 1 does not necessarily have to coincide with the direction of gravity.

The exhaust valve 25 is arranged at a position overlapping with 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 rod 252. The valve body 251 is a roughly conical portion located below the exhaust port 24. The diameter of the valve body 251 when viewed from above is larger than the diameter of the exhaust port 24 when viewed from above. The valve rod 252 is a roughly cylindrical portion extending upward from the upper end of the valve body 251. The upper end of the valve rod 252 is accommodated in the interior of the exhaust valve hydraulic cylinder 253 arranged above the cylinder 2, and is supported to be movable in the vertical direction.

The exhaust valve 25 is moved in the up-down direction by the hydraulic drive mechanism 7. As shown by the solid line in FIG. 1 , when the valve body 251 of the exhaust valve 25 moves 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, when the valve body 251 is located at the position shown by the two-dot chain in FIG. 1 , the valve body 251 contacts the peripheral portion of the exhaust port 24 and closes the exhaust port 24, so that 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 shown by the solid line in FIG. 1 is referred to as the "open position", and the position of the exhaust valve 25 shown by the two-dot chain is referred to as the "closed position". The exhaust valve 25 can move in the up-down direction between an open position and a closed position that is further up than the open position.

When the exhaust valve 25 is in the open position, the gas discharged from the exhaust port 24 to the outside of the cylinder 2 (hereinafter referred to as "exhaust") is guided to the exhaust pipe 42 through the exhaust path 241. In the actual diesel engine 1, multiple cylinders 2 are arranged in parallel, and the multiple cylinders 2 are connected to a sweeping pipe 41 and an exhaust pipe 42.

The exhaust gas in the exhaust pipe 42 is sent to the supercharger 5 as a turbocharger and supplied to the turbine 51 of the supercharger 5. The exhaust gas used for the rotation of the turbine 51 is discharged to the outside of the diesel engine 1 through a reduction catalyst (not shown) for reducing nitrogen oxides (NOX). In the compressor 52 of the supercharger 5, the rotational force generated by the turbine 51 is used to pressurize the intake air (air) sucked from the outside of the diesel engine 1. The pressurized air (hereinafter referred to as "swept air") is cooled in the air cooler 43 using a refrigerant such as seawater and then supplied to the swept air pipe 41. In this way, in the supercharger 5, the exhaust gas is used to pressurize the intake air to generate swept air.

The piston 3 can move in the cylinder 2 along the up and down direction in FIG1. In FIG1, the position of the piston 3 shown by the two-point chain is the top dead center, and the position of the piston 3 shown 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, roughly circular plate-shaped portion inserted into the cylinder liner 21. The piston rod 32 is a roughly cylindrical portion whose upper end is connected to the lower surface of the piston head 31. The lower end of the piston rod 32 is connected to a crank mechanism that is omitted from the illustration. In the diesel engine 1 illustrated in FIG1, the 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 burning 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 mounted on the cylinder head 22 with the front end facing the combustion chamber 20. The fuel supply pump 62 is connected to a fuel tank (not shown) via a fuel pipe, and delivers the fuel in the fuel tank to the fuel injection portion 61. The fuel injection portion 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 above-mentioned hydraulic drive mechanism 7.

Next, the operation of the diesel engine 1 is described. In the diesel engine 1, when the piston 3 rises from the bottom dead center and is located near the top dead center, the exhaust valve 25 is located in the closed position and the exhaust port 24 is closed. Therefore, the gas in the combustion chamber 20 (as described later, the sweeping air) is compressed. Then, the fuel is injected into the combustion chamber 20 from the fuel injection portion 61, and the vaporized fuel self-ignites, and the gas in the combustion chamber 20 burns (i.e., explodes). As a result, the piston 3 is pressed downward and moves to the bottom dead center. Furthermore, the gas in the combustion chamber 20 does not necessarily have to self-ignite, and the gas in the combustion chamber 20 can also be ignited using a spark plug or the like.

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

When the piston 3 descends to the vicinity of the bottom dead center and the upper surface of the piston head 31 moves to a position lower than the scavenging port 23, the scavenging port 23 opens, and the combustion chamber 20 and the scavenging chamber 231 are connected through the scavenging port 23. Thus, the scavenging air in the scavenging chamber 231 is supplied to the combustion chamber 20.

The piston 3 starts to rise after reaching the bottom dead center. The upper surface of the piston head 31 rises to a position above the sweeping port 23, thereby closing the sweeping port 23 and stopping the supply of sweeping air into the combustion chamber 20. Then, the exhaust port 24 is closed by the exhaust valve 25, and the combustion chamber 20 is sealed. As the piston 3 rises further, the sweeping air in the combustion chamber 20 is compressed. Then, when the piston 3 reaches the vicinity of the top dead center, fuel is injected into the combustion chamber 20 from the fuel injection portion 61, and the above-mentioned combustion occurs in the combustion chamber 20. In the diesel engine 1, the above-mentioned operation is repeated.

Next, the details of the hydraulic drive mechanism 7 are described. The hydraulic drive mechanism 7 includes a hydraulic drive pipeline 71, a hydraulic drive pipeline 72, a drive oil tank 73, a drive oil pump 74, and a drive oil supply unit 77. The drive oil tank 73 stores the drive oil. The drive oil pump 74 delivers the drive oil in the drive oil tank 73 to the hydraulic drive pipeline 71 and the hydraulic drive pipeline 72. The hydraulic drive pipeline 71 is connected to the exhaust valve hydraulic cylinder 253 and drives the exhaust valve 25. The hydraulic drive line 72 is connected to the fuel supply mechanism 6 and drives the fuel supply pump 62. In the following description, the hydraulic drive line 71 that drives the exhaust valve 25 is referred to as the "first hydraulic drive line 71". In addition, the hydraulic drive line 72 that drives the fuel supply pump 62 is referred to as the "second hydraulic drive line 72". The driving oil supply unit 77 supplies driving oil to the driving oil tank 73. The driving oil supply unit 77, for example, continuously measures the amount of driving oil stored in the driving oil tank 73, and if the amount of driving oil is less than a specified amount, the driving oil is supplied to the driving oil tank 73.

FIG2 is an enlarged cross-sectional view showing the exhaust valve hydraulic cylinder 253 and its vicinity. FIG2 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 path 713, a hydraulic piston 714, a spring 715, and a throttle valve 75. The flow path 713 is formed in the exhaust valve hydraulic cylinder 253. The hydraulic piston 714, the spring 715, and the throttle valve 75 are housed inside the exhaust valve hydraulic cylinder 253. A monitoring system 76 for monitoring the first hydraulic drive line 71 is provided near the throttle valve 75.

The piping 711 guides the driving oil sent from the driving oil pump 74 (see FIG1) to the flow path 713. In FIG2, the driving oil flowing in the flow path 713 is also marked with parallel oblique lines. The valve 712 is provided on the piping 711 to control the supply of the driving oil to the flow path 713. By opening and closing the valve 712, the state of the driving oil in the first hydraulic driving line 71 is switched between the boost state and the non-boost state. FIG2 shows the first hydraulic driving line 71 when it is not boosted.

The flow path 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 roughly cylindrical component with a cover. A spring 715 is housed inside the hydraulic piston 714. The lower end of the spring 715 contacts the upper end surface of the valve rod 252 of the exhaust valve 25. The valve rod 252 is pressed toward the spring 715 (i.e., upward) by the air piston 254 provided in the exhaust valve hydraulic cylinder 253. The spring 715 is, for example, a coil spring. The spring 715 may also be various elastic components other than a coil spring.

In the first hydraulic drive line 71 when the pressure is not increased, the valve rod 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 contacts or approaches the top cover of the exhaust valve hydraulic cylinder 253, and the exhaust valve 25 is in a closed state. On the other hand, in the first hydraulic drive line 71 when the pressure is increased, the spring 715 is pressed downward by the pressure of the boosted drive oil. Thereby, the spring 715 and the valve rod 252 resist the pressure of the air piston 254 and move downward, and the exhaust valve 25 becomes an open state. In the first hydraulic drive line 71, when the boost of the drive oil ends and returns to the non-boosted 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 becomes closed.

The driving oil in the exhaust valve hydraulic cylinder 253 flows out from the multiple throttle holes provided on the side wall of the exhaust valve hydraulic cylinder 253, and is received by the driving oil storage portion 255 provided on the lower side of the air piston 254 and temporarily stored. The driving oil stored in the driving oil storage portion 255 flows downward along the outer surface of the valve rod 252 from the gap between the driving oil storage portion 255 and the valve rod 252. In this way, the friction resistance is reduced in the sliding portion of the exhaust valve 25 (for example, the portion between the support portion supporting the valve rod 252 and the valve rod 252), and the exhaust valve 25 can move smoothly in the up and down directions. In addition, the sliding portion is hermetically sealed.

The driving oil flowing down from the driving oil reservoir 255 is temporarily stored as drain oil in the crankcase (not shown) located at the lower side of the cylinder 2. The drain oil is sucked up by the circulation pump, passes through the filter, etc. to be purified, and then returns to the driving oil tank 73 to be reused. In the following description, the flow path of the driving oil from the exhaust valve hydraulic cylinder 253 to the crankcase is called the "drain line".

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

FIG. 3 and FIG. 4 are enlarged cross-sectional views showing 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 first hydraulic drive line 71 is pressurized. The throttle valve 75 is a roughly cylindrical component centered on the center axis J1. In the example shown in FIG. 3, the center axis J1 is oriented in a roughly vertical direction. The length of the throttle valve 75 in the vertical direction is, for example, 4.3 cm 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 respectively substantially cylindrical members extending in substantially vertical directions with the center axis J1 as the center. The outer cylinder portion 751 has a lower opening 754 and an upper opening 755 at the lower end and the upper end, respectively. The inner cylinder portion 752 is arranged inside the outer cylinder portion 751 between the lower opening 754 and the upper opening 755. The inner cylinder portion 752 can move in the vertical direction between the position shown in FIG. 3 and the position shown in FIG. 4. The elastic member 753 is arranged between the outer side surface of the inner cylinder portion 752 and the inner side surface of the outer cylinder portion 751 in a compressed state in the vertical direction. The elastic member 753 presses the inner cylinder portion 752 downward. In the examples shown in FIGS. 3 and 4 , the elastic member 753 is a coil spring.

A plurality of throttle holes 756 are provided on the upper side of the inner cylinder 752, respectively penetrating the inner cylinder 752. In the throttle valve 75, the inner space of the inner cylinder 752 and the inner space of the outer cylinder 751 are connected through the plurality of throttle holes 756. In the example shown in FIG. 3 and FIG. 4, the four throttle holes 756 are arranged at approximately equal angles in the circumferential direction centered on the central axis J1. The number and arrangement of the throttle holes 756 can be appropriately changed.

In the first hydraulic drive line 71 when the pressure is not increased as shown in FIG3, the drive oil in the flow path 713 (see FIG2) flows into the throttle valve 75 through the lower opening 754, and flows upward in the inner space of the inner cylinder 752. The drive oil flows out from the inner space of the inner cylinder 752 through a plurality of throttle holes 756 to the space between the upper outer surface of the inner cylinder 752 and the inner surface of the outer cylinder 751, 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 flowing out of the throttle valve 75 to the outside. In the throttle valve 75, the lower opening 754 is the inlet of the driving oil, and the upper opening 755 is the outlet of the driving oil. In the following description, the lower opening 754 and the upper opening 755 of the throttle valve 75 are respectively referred to as "inlet 754" and "outlet 755".

On the other hand, in the first hydraulic drive line 71 during the boosting shown in FIG. 4, the inner cylinder 752 is pressed upward by the pressure of the boosted drive oil. As a result, the inner cylinder 752 moves upward while compressing the elastic member 753, and the outer surface of the upper end of the inner cylinder 752 contacts the inner surface of the outer cylinder 751. As a result, the outlet 755 is closed by the inner cylinder 752, and the outflow of the drive oil from the throttle valve 75 stops. In the throttle valve 75, when the boosting of the drive oil ends and returns to the non-boosted state, the inner cylinder 752 is pressed downward by the restoring force of the elastic member 753, and the outlet 755 is opened.

As shown in FIG2 , the monitoring system 76 includes the throttle valve 75, a sensor unit 761, a monitoring unit 762, and an outflow pipe 769. The sensor unit 761 includes a mounting unit 764 and a pressure sensor 765. The mounting unit 764 is mounted on the outer wall of the exhaust valve hydraulic cylinder 253 on the side of the buffer unit 716. A flow path is formed inside the mounting unit 764 for the drive oil flowing out from the buffer unit 716 to the outside of the exhaust valve hydraulic cylinder 253 to flow. The pressure sensor 765 is arranged at the lower side of the flow path of the mounting portion 764, and measures the pressure of the driving oil flowing in the flow path at the lower part of the flow path (i.e., the pressure of the driving oil flowing out of the outlet 755 of the throttle valve 75). The pressure sensor 765 is preferably arranged 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 pipe 769. The outflow pipe 769 is a pipe that extends upward from the outside of the exhaust valve hydraulic cylinder 253 to the upper side of the outlet 755 of the throttle valve 75, and then extends downward. The other end of the outflow pipe 769 is connected to the exhaust valve hydraulic cylinder 253 and communicates with the internal space of the exhaust valve hydraulic cylinder 253 at the upper side of the drive oil storage portion 255. Furthermore, the outflow pipe 769 can also be set inside the exhaust valve hydraulic cylinder 253.

The outflow line 769 returns the driving oil flowing out from the buffer section 716 to the outside of the exhaust valve hydraulic cylinder 253 to the inside of the exhaust valve hydraulic cylinder 253. The driving oil guided into the exhaust valve hydraulic cylinder 253 by the outflow line 769 is received by the driving oil storage section 255 and temporarily stored. As described above, the driving oil stored in the driving oil storage section 255 flows downward along the outer side surface of the valve rod 252 from the gap between the driving oil storage section 255 and the valve rod 252. Thereby, the friction resistance at the sliding part of the exhaust valve 25 is reduced, and the exhaust valve 25 can move smoothly in the up and down directions. In addition, the sliding portion is hermetically sealed.

If the buffer portion 716, the flow path inside the mounting portion 764, and the outflow pipe 769 are collectively referred to as the "outflow path 760", the outflow path 760 is a path that guides the driving oil flowing out of the outlet 755 of the throttle valve 75 to the sliding portion of the exhaust valve 25. As described above, the driving oil guided to the sliding portion is used as a lubricating oil to reduce friction. Furthermore, the outflow path 760 does not necessarily guide all of the driving oil flowing out of the throttle valve 75 to the sliding portion of the exhaust valve 25. The outflow path 760 preferably guides at least a portion of the driving oil flowing out of the throttle valve 75 to the sliding portion of the exhaust valve 25. The outlet flow path 760 is provided independently of the discharge line, and the discharge line is used for the flow of the drive oil discharged from a portion other than the throttle valve 75 of the first hydraulic drive line 71.

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

FIG5 is a diagram showing an example of the pressure of the driving oil flowing out from the throttle valve 75 to the outlet flow path 760. FIG5 shows the output from the pressure sensor 765 when the gas content of the driving oil supplied from the first hydraulic driving line 71 to the exhaust valve 25 is within the normal range (hereinafter also referred to as the "normal state"). In the following description, the periodic variation of the pressure of the driving oil flowing out from the outlet 755 of the throttle valve 75 in the normal state is referred to as the "baseline variation".

The normal state refers to a state in which the ratio of the gas contained in the drive oil supplied to the exhaust valve 25 relative to the drive oil is below a specified critical value. In other words, the normal state refers to a state in which the ratio 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 below a specified critical value. Furthermore, in the normal state, the exhaust valve 25 also operates normally.

In the following description, the 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, a large amount of air mixed with the drive oil supplied to the exhaust valve 25, or the oil amount in the first hydraulic drive line 71 is insufficient due to insufficient drive oil in the drive oil tank 73. Furthermore, even in this abnormal state, the operation of the exhaust valve 25 does not necessarily become abnormal. For example, even if the gas content of the drive oil supplied to the exhaust valve 25 is slightly greater than the normal range, the operation of the exhaust valve 25 will not become abnormal if it is maintained in a state close to the normal range. On the other hand, if the gas content of the driving oil supplied to the exhaust valve 25 continues to increase and exceeds the normal range, there is a concern that the exhaust valve 25 will shift from normal operation to abnormal operation.

As described above, the throttle valve 75 is a valve for exhausting the driving oil of the first hydraulic driving line 71, so the gas content of the driving oil flowing out from the outlet 755 of the throttle valve 75 is greater than the gas content of the driving oil supplied to the exhaust valve 25. In addition, if the gas content of the driving oil supplied to the exhaust valve 25 increases, the gas content of the driving oil flowing out from the outlet 755 of the throttle valve 75 also increases. Furthermore, the pressure of the driving oil flowing out from the outlet 755 of the throttle valve 75 is much lower than the pressure of the driving oil supplied to the exhaust valve 25. For example, the pressure of the driving oil flowing out from the throttle valve 75 is about one tenth of the pressure of the driving 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 marked with the symbol 90 in FIG. 5 is the baseline change of the pressure of the drive oil in one cycle (i.e., during the period when the crank angle changes from 0° to 360°). In the range of crank angles from 0° to about 120°, the first oil pressure drive pipeline 71 is in a non-boosted 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 approximately the same as the pressure of the drive oil when it is not boosted and is relatively low.

When the crank angle becomes about 120°, the first hydraulic drive line 71 becomes a boosted state, and the throttle valve 75 shifts from an open state to a 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 becomes a closed state. Therefore, when the crank angle is about 120°, the pressure of the drive oil measured by the pressure sensor 765 increases instantaneously, generating a peak value of the pressure in the baseline variation.

In the range of crank angle of about 120° to about 240°, the first hydraulic drive line 71 is in a boosting state, and the throttle valve 75 is in a closed state, so the pressure of the drive oil measured by the pressure sensor 765 is relatively low. In addition, in the range of crank angle of about 240° to 360°, the first hydraulic drive line 71 is in a non-boosting 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 variation of the driving oil within the crank angle range of about 300° to 360° is caused by the supply of driving oil using the driving oil supply part 77, rather than by the opening and closing of the throttle valve 75.

The standard variation shown in FIG. 5 is obtained, for example, by measuring the pressure of the driving oil with the pressure sensor 765 when the gas content of the driving oil supplied to the exhaust valve 25 is confirmed to be within the normal range. Alternatively, the standard variation can also be obtained by simulation, etc.

The monitoring unit 762 shown in FIG2 is, for example, a common computer. As shown in FIG6, 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 that connects the processor 81, the memory 82, and the input/output unit 83. The memory 82 stores programs and various information. The processor 81 performs various processing (for example, numerical calculation or image processing) while using the memory 82 according to the program stored in the memory 82. The input/output unit 83 includes a keyboard 85 and a mouse 86 that receive input from the operator, and a display 87 that displays output from the processor 81.

As shown in FIG2 , the monitoring unit 762 includes a storage unit 766, a detection unit 767, and an alarm unit 768. The storage unit 766 is mainly implemented by the memory 82 and stores various information. The detection unit 767 is mainly implemented by the processor 81 and detects the abnormal gas content rate in the first hydraulic drive pipeline 71 based on the information stored in the storage unit 766 and the output from the pressure sensor 765 (i.e., the measured value of the pressure sensor 765). The alarm unit 768 issues an alarm to the crew and the like when an abnormal gas content rate is detected. The alarm issued by the alarm unit 768 is, for example, a warning displayed on the display 87 or an alarm buzzer sound.

Specifically, the storage unit 766 stores the reference change of the pressure of the driving oil flowing out of the outlet 755 of the throttle valve 75. The storage unit 766 can store the entire reference change or a part of the reference change. In this embodiment, the peak pressure (i.e., the maximum value of the reference change) when the crank angle in the reference change is about 120° is pre-stored 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 outlet flow path 760 also increases. Therefore, the apparent volume elastic coefficient of the drive oil flowing in the outlet flow path 760 decreases, and as shown in Figures 7 and 8, the pressure pulsation of the drive oil flowing out from the throttle valve 75 to the outlet flow path 760 also decreases. The curves marked with symbols 91 and 92 in Figures 7 and 8 represent the periodic changes in the pressure of the drive oil flowing out from the throttle valve 75 to the outlet flow path 760 under abnormal conditions. In FIG. 7 and FIG. 8, the baseline variation shown in FIG. 5 is shown in dotted lines. The state shown in FIG. 8 has a higher gas content rate in the driving oil than the state shown in FIG. 7. In addition, in the state of FIG. 7, the operation of the exhaust valve 25 did not produce abnormalities, but in the state of FIG. 8, the operation of the exhaust valve 25 produced abnormalities.

The detection unit 767 compares the measured value of the pressure sensor 765 with the reference value under normal conditions stored in the storage unit 766 for the peak pressure when the crank angle is about 120° (i.e., the peak pressure of the drive oil before the outlet 755 of the throttle valve 75 is about to be closed). Then, when the difference between the reference value and the measured value of the pressure sensor 765 is greater than the specified critical value, it is determined that the gas content rate in the first hydraulic drive line 71 is abnormal (i.e., the gas content rate becomes abnormal greater than the normal range). If the detection unit 767 detects that the gas content rate is abnormal, the alarm unit 768 notifies the crew of the abnormal gas content rate.

The pressure sensor 765 can continuously measure the pressure of the driving oil in the outlet flow path 760, and can also intermittently measure the pressure of the driving oil in the outlet flow path 760 at a specified time. For example, in the case where the abnormal gas content rate is detected based on the peak pressure when the crank angle is about 120° as described above, the pressure sensor 765 can only measure the pressure of the driving oil when the crank angle is about 120°. In the above case, the pressure measurement using the pressure sensor 765 is preferably performed based on the drive control signal for the exhaust valve 25 that is synchronized with the crank angle.

In the detection unit 767, the value of the gas content rate of the driving oil in the first hydraulic driving line 71 can be obtained based on the measured value of the pressure sensor 765. For example, a table or a formula showing the relationship between the peak pressure of the driving oil flowing out of the outlet 755 of the throttle valve 75 and the gas content rate of the driving oil in the first hydraulic driving line 71 is stored in advance in the storage unit 766, and the gas content rate of the driving oil in the first hydraulic driving line 71 is obtained based on the measured value of the pressure sensor 765 and the table or the formula. Furthermore, in the detection unit 767, the gas content rate of the drive oil in the first hydraulic drive line 71 can also be obtained based on the difference between the measured value of the pressure sensor 765 and the reference value under normal conditions stored in the storage unit 766.

When the gas content rate is obtained in the above manner, the alarm unit 768 may also issue an alarm when the gas content rate of the drive oil in the first hydraulic drive pipeline 71 obtained by the detection unit 767 is greater than a specified critical value. For example, the alarm unit 768 issues a first alarm when the detection unit 767 detects that the gas content rate is abnormal, and issues a second alarm when the gas content rate obtained by the detection unit 767 increases to a level that causes abnormal operation of the exhaust valve 25 (i.e., becomes greater than the critical value).

In the detection unit 767, the peak pressure is not necessarily detected as abnormal gas content when the difference between the normal reference value and the measured value of the pressure sensor 765 is greater than the prescribed critical value, but may be detected as abnormal gas content in the first hydraulic drive line 71 when the difference between the normal reference value and the measured value of the pressure sensor 765 is greater than the prescribed critical value and the measured value of the pressure sensor 765 decreases continuously over a plurality of cycles. In this way, it is possible to prevent sudden mixing of gas that immediately returns to normal from being detected as abnormal gas content, thereby accurately detecting major abnormalities such as gradual increase in gas content in the first hydraulic drive line 71. Furthermore, the detection of abnormal gas content rate using the detection unit 767 is not limited to the case where the measured value of the peak pressure decreases continuously in multiple cycles, and all cases where the peak pressure is smaller than the reference value by a certain degree or more can be detected as abnormal gas content rate.

As described above, the monitoring system 76 monitors the hydraulic drive line (i.e., the first hydraulic drive line 71) of the diesel engine 1. The monitoring system 76 includes the throttle valve 75, the outlet flow path 760, the pressure sensor 765, and the detection unit 767. The throttle valve 75 has the inlet 754 and the outlet 755 of the drive oil from the first hydraulic drive line 71. The throttle valve 75 closes the outlet 755 due to the pressure of the drive oil when the drive oil is pressurized, and opens the outlet 755 when the drive oil is not pressurized to exhaust the first hydraulic drive line 71. The outlet flow path 760 guides the drive oil flowing out of 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 outlet flow path 760. The detection unit 767 detects the abnormality of the gas content rate in the first hydraulic drive pipeline 71 based on the measured value of the pressure sensor 765.

As described above, the throttle valve 75 is a valve for exhausting the drive oil in the first hydraulic drive line 71, so 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 drive target (i.e., the exhaust valve 25) of the first hydraulic drive line 71. In addition, the pressure of the drive oil flowing out from the throttle valve 75 is lower than the pressure of the drive oil supplied to the drive target. Therefore, when the gas content rate in the driving oil supplied to the driven object changes from a normal state to an abnormal state, the apparent volume elastic coefficient of the driving oil flowing out of the throttle valve 75 decreases more than the driving oil supplied to the driven object, and the amplitude of the pressure fluctuation decreases more. In other words, the influence of the gas contained in the driving oil, is greater on the driving oil flowing out of the throttle valve 75 than on the driving oil supplied to the driven object.

Therefore, as described above, by measuring the pressure of the drive oil flowing out of the outlet 755 of the throttle valve 75, early detection of abnormal gas content in the first hydraulic drive line 71 can be achieved. In the diesel engine 1, if the abnormal gas content in the first hydraulic drive line 71 can be detected before the operation abnormality of the driven object of the first hydraulic drive line 71 occurs, the operation abnormality of the driven object can be prevented in advance. As a result, the failure of the diesel engine 1 can be prevented.

As described above, the driving object of the first hydraulic drive line 71 preferably includes the exhaust valve 25 of the diesel engine 1. In this way, it is possible to prevent or suppress abnormal operation of the exhaust valve 25 which plays an important role in the driving of the diesel engine 1.

As described above, the detection unit 767 preferably detects the abnormal gas content rate in the first hydraulic drive line 71 by comparing the measured value of the pressure sensor 765 with the reference value under normal conditions with respect to the peak pressure of the drive oil just before the outlet 755 of the throttle valve 75 is closed. In this way, the difference between the measured pressure value of the drive oil under normal conditions and the measured pressure value of the drive oil under abnormal conditions becomes larger, so that the abnormal gas content rate in the first hydraulic drive line 71 can be detected with good accuracy.

In addition, it is preferable that the detection unit 767 detects an abnormal gas content in the hydraulic drive line when the peak pressure decreases continuously over multiple cycles. In this way, a single decrease in peak pressure caused by sudden gas mixing (i.e., noise) will not be detected as an abnormal gas content, so that a major gas content abnormality such as a gradual increase in the gas content in the first hydraulic drive line 71 can be detected with good accuracy.

As described above, it is preferable that the measurement using the pressure sensor 765 is performed based on the drive control signal for the drive target of the first hydraulic drive pipeline 71. In this way, the pressure at a specified time (for example, the peak pressure of the drive oil just before the outlet 755 of the throttle valve 75 is about to be closed) can be easily obtained in the periodic change of the pressure of the drive oil in the outlet flow path 760.

As described above, it is preferable that the outlet flow path 760 is provided independently of the exhaust line, and the exhaust line is for the drive oil discharged from the portion other than the throttle valve 75 of the first hydraulic drive line 71 to flow. In this way, the influence of the pressure change of the drive oil flowing out of the throttle valve 75 can be prevented or reduced, and the pressure of the drive oil flowing out of the throttle valve 75 can be measured with good accuracy. As a result, the abnormal gas content rate in the first hydraulic drive line 71 can be detected with good accuracy.

As described above, it is preferable that the detection unit 767 obtains the gas content rate in the first hydraulic drive line 71 based on the measured value of the pressure sensor 765. In this way, the degree of abnormality of the gas content rate in the first hydraulic drive line 71 (i.e., whether it is a slight abnormality or a serious abnormality) can be grasped. As a result, appropriate measures such as maintenance can be selected according to the degree of abnormality of the gas content rate.

It is further preferred that the monitoring system 76 further includes an alarm unit 768, which issues an alarm when the gas content rate in the first hydraulic drive line 71 obtained by the detection unit 767 is greater than a specified critical value. Therefore, the crew can identify a serious gas content rate abnormality at an early stage, which is likely to cause an abnormal operation of the driving object of the first hydraulic drive line 71.

Various changes can be made in the monitoring system 76.

For example, in the detection unit 767, the measured value is compared with the reference value for the peak pressure of the drive oil just before the outlet 755 of the throttle valve 75 is closed, but the abnormal gas content rate in the first hydraulic drive line 71 can also be detected by comparing the measured value with the reference value for the pressure of other parts of the pressure change (for example, the peak pressure when the crank angle is about 340°).

The pressure measurement of the driving oil using the pressure sensor 765 does not necessarily have to be performed based on the driving control signal for the driving object (i.e., the exhaust valve 25) of the first oil pressure driving pipeline 71, and can be performed continuously and always, for example.

In the monitoring system 76, the outflow pipeline 769 independent of the exhaust pipeline can also be omitted, and the driving oil flowing out of the outlet 755 of the throttle valve 75 can be directly guided to the exhaust pipeline. In addition, the driving oil flowing out of the throttle valve 75 of the first hydraulic drive pipeline 71 does not have to be guided to the sliding part of the exhaust valve 25 and used as lubricating oil.

In the detection unit 767, it is not necessary to determine the gas content rate in the first hydraulic drive pipeline 71. In addition, the alarm unit 768 may not be based on the gas content rate, but always issues an alarm when an abnormal gas content rate is detected. Furthermore, the alarm unit 768 is not necessarily provided.

The throttle valve 75 is not limited to the above structure, but may also have other various structures. 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 does not have to be the first hydraulic drive line 71 for driving the exhaust valve 25, but may be a hydraulic drive line for driving other driving objects. For example, the second hydraulic drive line 72 for driving the fuel supply pump 62 may be monitored by the monitoring system 76.

The diesel engine 1 equipped with the monitoring system 76 is not limited to a two-stroke engine, but may be a four-stroke engine. In addition, the monitoring system 76 may be installed not only in a diesel engine used as a main engine of a ship, but also in various diesel engines such as a diesel engine for power generation or a diesel engine for automobiles.

The above-mentioned embodiments and the configurations of various variations can be appropriately combined as long as they do not contradict each other.

The invention has been described and illustrated in detail, but the descriptions set forth are illustrative and not limiting. Therefore, various modifications and forms are possible without departing from the scope of the invention.

25: Exhaust valve

252: Valve stem

253: Exhaust valve hydraulic cylinder

254: Air piston

255: Drive oil storage unit

71: First hydraulic drive pipeline (hydraulic drive pipeline)

711: Piping

712: Valve

713: Flow path

714: Hydraulic piston

715: Spring

716: Buffer Department

75:Throttle valve

755: (throttle valve) outlet upper opening

76: Monitoring system

760: Outflow path

761: Sensor Department

762: Surveillance Department

764: Installation Department

765: Pressure sensor

766: Storage Department

767: Testing Department

768: Police Department

769: Outflow pipeline

Claims (8)

A monitoring system monitors a hydraulic drive line of a diesel engine, the monitoring system comprising: a throttle valve having an inlet and an outlet for drive oil from the hydraulic drive line, the outlet being closed by the pressure of the drive oil when the drive oil is pressurized, and the outlet being opened to exhaust the hydraulic drive line when the drive oil is not pressurized; an outlet flow path guiding the drive oil flowing out of the outlet of the throttle valve; a pressure sensor measuring the pressure of the drive oil flowing out of the outlet in the outlet flow path; and a detection unit detecting an abnormal gas content rate in the hydraulic drive line based on a measured value of the pressure sensor. The monitoring system as described in claim 1, wherein the detection unit detects the abnormal gas content rate in the hydraulic drive pipeline by comparing the measured value of the pressure sensor with the reference value under normal conditions with respect to the peak pressure of the drive oil just before the outlet of the throttle valve is closed. The monitoring system as described in claim 2, wherein the detection unit detects that the gas content rate in the hydraulic drive pipeline is abnormal when the peak pressure decreases continuously over multiple cycles. A monitoring system as described in claim 1, wherein the measurement using the pressure sensor is performed based on a drive control signal for a drive object of the hydraulic drive pipeline. A monitoring system as described in claim 1, wherein the outlet flow path is provided independently of a discharge line, and the discharge line is used for the flow of drive oil discharged from a portion other than the throttle valve of the hydraulic drive line. A monitoring system as described in claim 1, wherein the detection unit obtains the gas content rate in the hydraulic drive pipeline based on the measured value of the pressure sensor. The monitoring system as described in claim 6 further includes an alarm unit, which issues an alarm when the gas content in the hydraulic drive pipeline obtained by the detection unit is greater than a specified critical value. A monitoring system as described in any one of claim 1 to claim 7, wherein the driving object of the oil pressure drive pipeline includes an exhaust valve of a diesel engine.