JP2020056354A - Operation monitoring system - Google Patents

Abstract

To automatically detect an abnormality of a two-stage type hydraulic actuator.SOLUTION: In an operation monitoring system for a hydraulic actuator 72, a monitoring unit comprises a first sensor 55, a second sensor (namely a second upper sensor 56 and/or a second lower sensor 57), and a detection unit. The first sensor 55 measures a position of a first piston 84 in a movement path 80 in a noncontact manner. The second sensor measures a position of a second piston 85 in the movement path 80 in the noncontact manner. The detection unit detects an abnormality of the hydraulic actuator 72 by comparing positions of the first piston 84 and the second piston 85 during normal operation of the hydraulic actuator 72, and measured values of the first sensor 55 and the second sensor. The operation monitoring system can automatically detect the abnormality of the hydraulic actuator 72.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an operation monitoring system of a hydraulic actuator provided in a hydraulic drive line of a diesel engine.

  Conventionally, in an internal combustion engine such as a diesel engine, operation monitoring of an intake valve or an exhaust valve of a combustion chamber is performed. For example, in Patent Literature 1, a proximity sensor 7 is disposed at a position facing a detected portion 5 attached to an intake valve IV of an internal combustion engine, and outputs a detection signal when the detected portion 5 approaches. Then, based on the output from the proximity sensor 7, it is determined whether or not the opening / closing timing of the intake valve IV is normal.

  Patent Literature 2 discloses an electromagnetic actuator 1 that is attached to an intake / exhaust valve 2 and drives the intake / exhaust valve 2. The actuator 1 includes a closed magnet 3 and an open magnet 4 that are electromagnets, and a thin plate-shaped anchor 5 that moves up and down between the electromagnets. In the actuator 1, the position of the anchor 5 (ie, the closed position or the open position) is detected by the sensor 10, and when the sensor signal disappears, it is determined that the sensor 10 has failed or the actuator 1 has failed.

JP-A-2004-68779 JP 2001-20801 A

  By the way, in a marine diesel engine used as a main engine of a ship, in a hydraulic drive line for driving an exhaust valve, a cylindrical first piston and a first piston inserted inside the first piston and individually moved. Some are provided with a two-stage hydraulic actuator with a possible second piston. The two-stage hydraulic actuator requires a relatively large driving force at the start of valve opening, and is suitable for driving an exhaust valve, which preferably has a relatively small driving force during the valve opening operation.

  In the marine diesel engine, the operation of the exhaust valve is monitored, but the operation of the hydraulic actuator is not monitored. However, when an abnormality occurs in the hydraulic actuator, the abnormality of the operation of the exhaust valve does not always occur immediately. Therefore, even if the operation of the exhaust valve is monitored, it takes time to detect the abnormality of the hydraulic actuator, and the malfunction due to the abnormality may be increased. On the other hand, an operation monitoring system of a solenoid valve having a simple structure (that is, an electromagnetic actuator) as in Patent Document 2 has a complicated structure like the above-described two-stage hydraulic actuator, and performs complicated operations. It is difficult to monitor the operation of the actuator.

  The present invention has been made in view of the above problems, and has as its object to automatically detect an abnormality of the hydraulic actuator in the above-described two-stage hydraulic actuator.

  The invention according to claim 1 is an operation monitoring system of a hydraulic actuator provided in a hydraulic drive line of a diesel engine, wherein the hydraulic actuator is connected to a drive target via a hydraulic pipe, and a drive oil in the hydraulic actuator is provided. A drive control unit for controlling a flow, and a monitoring unit for monitoring the operation of the hydraulic actuator, wherein the hydraulic actuator has a cylindrical hydraulic cylinder having a cylindrical moving path facing vertically, and An upper lid portion closing an upper end of the path and having an upper opening smaller in diameter than the moving path; a lower lid section closing a lower end of the moving path and having a lower opening smaller in diameter than the moving path; A first cylindrical piston that moves vertically in the moving path, and a first piston that moves vertically in the moving path and A second piston inserted inside the first piston, wherein when the driven object is shifted from the first state to the second state, the drive control unit drives the driven object from the lower opening to the movement path. Oil flows into the first piston and the second piston upward from a lower end position where the first piston contacts the lower lid and the second piston contacts the first piston in the vertical direction. And the first piston is locked by the hydraulic cylinder at an intermediate position, and the second piston moves further upward to an upper end position where it contacts the upper lid, and Due to the movement of the piston and the second piston, the driving oil is sent out to the driven object through the hydraulic pipe connected to the upper opening, and the driven object is moved from the second state to the first state. When the shift is made, the drive control unit causes the drive oil of the movement path to flow out from the lower opening, the second piston moves from the upper end position to the intermediate position, and the first piston moves vertically to the first piston. A first sensor that moves from the intermediate position to the lower end position together with the first piston in contact with the first piston and measures the position of the first piston in the movement path in a non-contact manner; A second sensor that measures the position of the second piston in the movement path in a non-contact manner, the positions of the first piston and the second piston during normal operation of the hydraulic actuator, the first sensor and the second sensor. A detecting unit that compares the measured value of the two sensors and detects an abnormality of the hydraulic actuator.

  The invention according to claim 2 is the operation monitoring system according to claim 1, wherein the driven object is an exhaust valve of a diesel engine.

  A third aspect of the present invention is the operation monitoring system according to the first or second aspect, wherein a plurality of circumferentially arranged first oil grooves are arranged on a side surface of the first piston. A plurality of circumferentially arranged second oil grooves, each of which is arranged in a vertical direction, provided on a side surface of the second piston, and the first sensor is provided with a vertical position of the plurality of first oil grooves. And the second sensor measures the position of the second piston by detecting the vertical position of the plurality of second oil grooves.

  According to a fourth aspect of the present invention, in the operation monitoring system according to any one of the first to third aspects, the abnormality detected by the detection unit causes the drive target to move from the first state to the second state. When shifting to the second state, the second piston starts moving upward from the lower end position prior to the first piston, and the first piston moves below the second position below the intermediate position. Includes an abnormality that collides with the piston from below.

  According to a fifth aspect of the present invention, in the operation monitoring system according to any one of the first to fourth aspects, the abnormality detected by the detection unit is such that the first piston and the second piston have Includes an abnormality that does not reach the lower end position when moving downward from the intermediate position.

  The invention according to claim 6 is the operation monitoring system according to any one of claims 1 to 5, wherein the second piston is inserted into the upper opening in a state where the second piston is located at the upper end position. A convex portion protrudes upward from the upper surface of the second piston, and the monitoring unit acquires a speed of the upper insertion speed of the second piston when the upper convex portion is inserted into the upper opening. Further comprising a unit, wherein the detection unit compares the upper insertion speed acquired by the speed acquisition unit and the upper insertion speed of the second piston during normal operation of the hydraulic actuator, and the vicinity of the upper end position The abnormal speed of the second piston is detected in the above.

  The invention according to claim 7 is the operation monitoring system according to any one of claims 1 to 6, wherein the second piston is inserted into the lower opening in a state where the second piston is located at the lower end position. A convex portion projects downward from the lower surface of the second piston, and the monitoring unit acquires a speed of the second piston when the lower convex portion is inserted into the lower opening. Further comprising a unit, wherein the detection unit compares the lower insertion speed obtained by the speed obtaining unit with the lower insertion speed of the second piston during normal operation of the hydraulic actuator, and detects the vicinity of the lower end position. The abnormal speed of the second piston is detected in the above.

  According to the present invention, the abnormality of the hydraulic actuator can be automatically detected.

FIG. 1 is a diagram illustrating a configuration of a diesel engine according to one embodiment. FIG. 3 is a block diagram illustrating functions of a control system. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. FIG. 5 is a diagram illustrating the vertical positions of a first piston and a second piston during a normal operation. It is a figure which shows the position of the 1st piston at the time of abnormal operation, and a 2nd piston in the up-down direction. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is a figure which shows the position of the 1st piston at the time of abnormal operation, and a 2nd piston in the up-down direction. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is sectional drawing of a hydraulic drive system. It is a figure which shows the position of the 1st piston and the 2nd piston at the time of abnormal operation at the up-down direction. It is sectional drawing of a hydraulic drive system. It is a figure which shows the position of the 1st piston and the 2nd piston at the time of abnormal operation at the up-down direction. It is sectional drawing of a hydraulic drive system. It is sectional drawing of another hydraulic drive system.

  FIG. 1 is a diagram showing a configuration of a diesel engine 1 according to one embodiment of the present invention. The diesel engine 1 is, for example, a two-stroke engine used as a main engine of a ship.

  The diesel engine 1 includes a cylinder 2, a piston 3, a scavenging passage 41, an exhaust passage 42, an air cooler 43, a supercharger 5, a control system 6, and a hydraulic drive system 7. The cylinder 2 is a substantially cylindrical member with a lid centered on a central axis extending in the vertical direction in FIG. The piston 3 is a substantially columnar member centered on the central axis, and the upper part thereof is disposed inside the cylinder 2. The piston 3 is movable in a vertical direction. Note that the vertical direction in FIG. 1 does not necessarily need to be parallel to the direction of gravity.

  The cylinder 2 includes a cylinder liner 21, a cylinder cover 22, and an exhaust valve 25. The cylinder liner 21 is a substantially cylindrical member centered on the central axis. The cylinder cover 22 is a substantially cylindrical member with a cover attached to an upper portion of the cylinder liner 21. An exhaust port 24 is formed in the canopy of the cylinder cover 22. The exhaust port 24 is connected to an exhaust channel 42.

  The exhaust port 24 is opened and closed by an exhaust valve 25. The exhaust valve 25 includes a valve body 251 and a valve rod 252. The valve body 251 is a substantially conical part located below the exhaust port 24. The diameter of the valve body 251 in a plan view is larger than the diameter of the exhaust port 24 in a plan view. The valve stem 252 is a substantially columnar part extending upward from the upper end of the valve body 251. The upper end of the valve rod 252 is housed inside an exhaust valve hydraulic cylinder 253 provided above the cylinder 2 and is supported so as to be movable in the vertical direction.

  The exhaust valve 25 is connected to the hydraulic drive system 7 and is moved up and down by the hydraulic drive system 7. The structure and the like of the hydraulic drive system 7 will be described later. As shown by a solid line in FIG. 1, the exhaust port 25 is opened when the exhaust valve 25 is separated downward from the exhaust port 24. In addition, as shown by a two-dot chain line in FIG. 1, the exhaust valve 25 contacts the cylinder cover 22 and overlaps the exhaust port 24, thereby closing the exhaust port 24. The operation of the exhaust valve 25 is monitored by a monitoring system (not shown).

  A scavenging port 23 is provided near the lower end of the cylinder liner 21. The scavenging port 23 is a set of a large number of through holes formed in a circumferential arrangement on the side surface of the cylinder liner 21. The scavenging port 23 is connected to the scavenging flow path 41.

  The piston 3 includes a piston crown 31 and a piston rod 32. The piston crown 31 is a relatively thick, substantially disk-shaped part centered on the central axis. The piston crown 31 is arranged inside the cylinder liner 21. The piston rod 32 is a substantially columnar portion extending downward from the lower surface of the piston crown 31. The lower end of the piston rod 32 is connected to a crank mechanism (not shown). The piston 3 reciprocates in the vertical direction by the crank mechanism. In FIG. 1, the piston 3 located at the bottom dead center of the reciprocating movement is drawn by a solid line, and the piston 3 located at the top dead center is drawn by a two-dot chain line.

  In the diesel engine 1, the space surrounded by the cylinder liner 21, the cylinder cover 22, the exhaust valve 25, and the upper surface of the piston crown 31 (that is, the upper surface of the piston 3) is a combustion chamber 20 for burning fuel and air. is there.

  The scavenging gas is supplied to the combustion chamber 20 from the scavenging flow channel 41 via the scavenging port 23 described above. The scavenging passage 41 includes a scavenging chamber 411 and a scavenging receiver 412. The scavenging chamber 411 is a space (ie, scavenging pipe) provided around the scavenging port 23 of the cylinder liner 21. The scavenging port 23 communicates with the scavenging receiver 412 via the scavenging chamber 411. The scavenging receiver 412 is a large, substantially cylindrical container that supplies scavenging air to the scavenging chamber 411.

  Gas (i.e., combustion gas) generated by combustion of fuel and air in the combustion chamber 20 is discharged to the exhaust passage 42 via the exhaust port 24. The exhaust passage 42 is a conduit through which gas discharged from the combustion chamber 20 (hereinafter, referred to as “exhaust”) flows. The exhaust passage 42 includes an exhaust pipe 421 and an exhaust receiver 422. The exhaust pipe 421 is a pipe that connects the exhaust port 24 and the exhaust receiver 422. The exhaust receiver 422 is a large, substantially cylindrical container that receives exhaust gas from the combustion chamber 20. Note that the combustion chamber 20 can also be regarded as a part of the exhaust passage 42 through which the exhaust flows.

  In the diesel engine 1, a plurality of sets of cylinders 2 and pistons 3 are provided, and a plurality of combustion chambers 20 are connected to one scavenging receiver 412 and one exhaust receiver 422. That is, the scavenging receiver 412 is a scavenging manifold for distributing and supplying scavenging air to the plurality of combustion chambers 20. Further, the exhaust receiver 422 is an exhaust manifold (also referred to as an exhaust manifold) in which exhaust exhausted from the plurality of combustion chambers 20 is collected.

  The exhaust gas collected by the exhaust receiver 422 is sent to the supercharger 5 after being subjected to a denitration process by a denitration system (not shown). The supercharger 5 is a turbocharger including a turbine 51 and a compressor 52. In the supercharger 5, the intake air is pressurized by using the exhaust gas to generate scavenging air.

  Specifically, the exhaust gas sent from the exhaust receiver 422 to the supercharger 5 causes the turbine 51 to rotate. Exhaust gas used for rotation of the turbine 51 is discharged from a flue (not shown) to the outside of the diesel engine 1. The compressor 52 pressurizes and compresses intake air (air) taken in from the outside of the diesel engine 1 via an intake passage by using the rotational force generated in the turbine 51 (that is, using the rotation of the turbine 51 as power). I do. The pressurized air (that is, the above-described scavenging air) is cooled by the air cooler 43 and then supplied to the scavenging receiver 412, and is supplied from the scavenging receiver 412 to each combustion chamber 20.

  The control system 6 is, for example, a programmable logic controller (PLC: Programmable Logic Controller). The PLC includes a processor, a memory, an input / output unit, and a bus. The bus is a signal circuit that connects the processor, the memory, and the input / output unit. The memory stores programs and various information. The processor executes various processes (for example, numerical operations and the like) using the memory and the like according to a program and the like stored in the memory. The input / output unit receives an input from an operator and a signal input from another device, and outputs a signal to another device.

  The PLC performs processing based on a predetermined program, and thereby each function of the control system 6 shown in FIG. 2, that is, the valve control unit 61, the detection unit 62, the position acquisition unit 63, the speed acquisition unit 64, and the storage unit 65 Is realized. The valve control unit 61 is mainly realized by a processor, and controls opening and closing of a solenoid valve 74 (described later) of the hydraulic drive system 7 in accordance with the angle of the crank mechanism described above. The detection unit 62 is mainly realized by a processor, and detects an abnormality of the hydraulic drive system 7. The position acquisition unit 63 is mainly realized by a processor, and acquires the positions of a first piston 84 and a second piston 85 described later in the vertical direction. The speed acquisition unit 64 is mainly realized by a processor, and acquires the speeds of the first piston 84 and the second piston 85. The storage unit 65 is mainly realized by a memory, and stores various information. The control system 6 may be a general computer system including a keyboard, a display, and the like, or may be a circuit board and the like. The control system 6 may include a plurality of arbitrary configurations among a PLC, a computer system, a circuit board, and the like.

  FIG. 3 and FIG. 4 are cross-sectional views illustrating the configuration of the hydraulic drive system 7. FIG. 3 shows a partial configuration of the hydraulic drive system 7 in a side view. The hydraulic drive system 7 includes a hydraulic pipe 71, a hydraulic actuator 72, a lower pipe 73, a solenoid valve 74, and an accumulator 75. In the following description, the vertical direction in FIGS. 3 and 4 is simply referred to as “vertical direction”. The vertical direction in FIGS. 3 and 4 may be parallel to the direction of gravity, but need not necessarily be parallel to the direction of gravity.

  The hydraulic piping 71 connects the hydraulic actuator 72 and the exhaust valve 25 (see FIG. 1) to which the hydraulic actuator 72 is driven. The hydraulic pipe 71 extends from the inside of the exhaust valve hydraulic cylinder 253 (see FIG. 1) to the outside, and is connected to the upper opening 821 of the hydraulic actuator 72. The lower pipe 73 connects the lower opening 831 of the hydraulic actuator 72 and the accumulator 75. The accumulator 75 is a storage container that stores high-pressure driving oil. The solenoid valve 74 is provided on the lower pipe 73. The solenoid valve 74 switches the connection destination of the hydraulic actuator 72 between the accumulator 75 and a drain line (not shown) by being controlled by the valve control unit 61 (see FIG. 2) of the control system 6. Thereby, the flow of the driving oil in the hydraulic actuator 72 is controlled. In other words, the solenoid valve 74 and the valve control unit 61 are the drive control unit 66 that controls the flow of the drive oil in the hydraulic actuator 72.

  The hydraulic actuator 72 is a substantially cylindrical member with a cover and a bottom provided in the hydraulic drive line of the exhaust valve 25 in the diesel engine 1. The internal space of the hydraulic actuator 72 is a movement path 80 through which a first piston 84 and a second piston 85 described later move. The hydraulic actuator 72 pressurizes the drive oil in the hydraulic pipe 71 to move the exhaust valve 25 (see FIG. 1) downward and open the exhaust port 24. When the pressurization of the drive oil by the hydraulic actuator 72 is released, the exhaust valve 25 is moved upward by an air piston provided in the exhaust valve hydraulic cylinder 253, and the exhaust port 24 is closed by the exhaust valve 25. Is done.

  The hydraulic actuator 72 includes a hydraulic cylinder 81, an upper lid part 82, a lower lid part 83, a first piston 84, and a second piston 85. That is, the hydraulic actuator 72 is a two-stage hydraulic actuator including two pistons. The hydraulic cylinder 81 is a substantially cylindrical member centered on the central axis J1. The hydraulic cylinder 81 has the above-described movement path 80 having a substantially columnar shape that faces in the vertical direction.

  The movement route 80 includes a route upper portion 801, a route central portion 802, and a route lower portion 803. The route upper portion 801, the route central portion 802, and the route lower portion 803 are connected in this order in the vertical direction from the upper side to the lower side. The path upper part 801, the path central part 802, and the path lower part 803 are each a substantially cylindrical space centered on the central axis J1. The diameter (i.e., the inner diameter) of the path center 802 is smaller than the diameter of the path upper part 801 and the diameter of the path lower part 803. The diameter of the upper path 801 is substantially the same over substantially the entire length in the vertical direction. The diameter of the path center portion 802 is also substantially the same over substantially the entire length in the vertical direction. The diameter of the lower path portion 803 is also substantially the same over substantially the entire length in the vertical direction.

  The upper lid 82 is a substantially disk-shaped member connected to the upper end of the hydraulic cylinder 81 and closing the upper end of the movement path 80. An upper opening 821 smaller in diameter than the upper path 801 of the moving path 80 is provided at the center of the lower surface of the upper lid portion 82 (that is, the upper end surface of the moving path 80). The upper opening 821 is connected to the hydraulic pipe 71 via a driving oil flow path formed inside the upper cover 82. The upper opening 821 has a substantially circular shape centered on the central axis J1 in plan view.

  The lower lid 83 is a substantially disk-shaped member that closes the lower end of the movement path 80 connected to the lower end of the hydraulic cylinder 81. At the center of the upper surface of the lower cover 83 (that is, the lower end surface of the moving path 80), a lower opening 831 having a smaller diameter than the lower path 803 of the moving path 80 is provided. More specifically, a substantially disk-shaped recess 832 that is recessed downward is formed on the upper surface of the lower lid 83, and a lower opening 831 is provided at the center of the bottom surface of the recess 832. The diameter of the concave portion 832 is larger than the diameter of the lower opening 831. The lower opening 831 is connected to the lower pipe 73 via a drive oil flow path formed inside the lower lid 83. The lower opening 831 has a substantially circular shape centered on the central axis J1 in plan view.

  In the example shown in FIG. 3, the hydraulic cylinder 81, the upper lid part 82, and the lower lid part 83 are separate members. The hydraulic cylinder 81 and the upper lid 82 may be a single member. Further, the hydraulic cylinder 81 and the lower lid 83 may be a single connected member.

  The first piston 84 is a substantially cylindrical member centered on the central axis J1. The first piston 84 is arranged in the movement path 80 and is movable in the movement path 80 in the vertical direction. The first piston 84 includes a first piston upper portion 841 and a first piston lower portion 842. Each of the first piston upper portion 841 and the first piston lower portion 842 is a substantially cylindrical portion centered on the central axis J1. The first piston lower part 842 is connected to the lower end of the first piston upper part 841. The first piston upper part 841 and the first piston lower part 842 are preferably one-piece members. The first piston lower portion 842 projects radially outward around the central axis J1 from the outer surface of the first piston upper portion 841 over the entire circumference in the circumferential direction around the central axis J1. In the following description, the circumferential direction and the radial direction around the center axis J1 are also simply referred to as “the circumferential direction” and the “radial direction”.

  The first piston lower part 842 is arranged in a path lower part 803 of the movement path 80. In the state illustrated in FIGS. 3 and 4, the first piston upper portion 841 is disposed over the lower path portion 803, the central path portion 802, and the upper path portion 801. The vertical length of the first piston 84 is longer than the total vertical length of the path center 802 and the path lower part 803. Therefore, the upper end of the first piston 84 is located above the upper end of the path center portion 802 (that is, in the upper part of the path 801) regardless of the vertical position of the first piston 84.

  The inner diameter and the outer diameter of the first piston upper portion 841 are substantially the same over substantially the entire length in the vertical direction. The inner diameter and the outer diameter of the first piston lower portion 842 are also substantially the same over substantially the entire length in the vertical direction. The inner diameter of the first piston lower part 842 is substantially the same as the inner diameter of the first piston upper part 841. The outer diameter of the first piston lower part 842 is larger than the outer diameter of the first piston upper part 841. The outer diameter of the first piston lower part 842 is larger than the diameter of the concave part 832 of the lower lid 83. The inner diameter of the first piston lower part 842 is smaller than the diameter of the recess 832.

  The outer diameter of the first piston upper part 841 is substantially the same as the diameter of the path center part 802 of the movement path 80. The outer side surface of the first piston upper portion 841 radially opposes the side surface of the path center portion 802 with a very small gap therebetween. Driving oil is present in the gap. A plurality of first oil grooves 843 arranged at substantially equal intervals in the vertical direction are provided on the outer surface of the first piston upper portion 841. Each of the plurality of first oil grooves 843 is a circumferential recess provided over substantially the entire outer surface of the first piston upper portion 841. Each first oil groove 843 holds the driving oil between the outer surface of the first piston upper part 841 and the side surface of the path center part 802. Thereby, the sliding resistance generated between the first piston upper portion 841 and the hydraulic cylinder 81 is reduced. The outer diameter of the first piston lower part 842 is smaller than the diameter of the path lower part 803 of the movement path 80. The outer diameter of the first piston lower part 842 is larger than the diameter of the path center part 802. Therefore, the first piston lower part 842 can move in the vertical direction only inside the path lower part 803.

  The first piston 84 is movable between a bottom dead center indicated by a solid line in FIG. 3 and a top dead center indicated by a two-dot chain line. In a state where the first piston 84 is located at the bottom dead center, the substantially annular lower surface of the first piston lower portion 842 surrounds the upper surface of the lower lid portion 83 (that is, the movement path 80) around the concave portion 832 of the lower lid portion 83. (Lower end face of In a state where the first piston 84 is located at the top dead center, the substantially annular upper surface of the first piston lower portion 842 extends radially outward from the upper end surface of the path lower portion 803 (that is, the lower end edge of the path central portion 802). (A substantially annular surface).

  The second piston 85 is a substantially columnar member centered on the central axis J1. The second piston 85 is disposed in the movement path 80. At least a part of the second piston 85 is always inserted inside the first piston 84. The first piston 84 is vertically movable in the movement path 80 independently of the first piston 84.

  The second piston 85 includes a second piston upper part 851 and a second piston lower part 852. Each of the second piston upper part 851 and the second piston lower part 852 is a substantially columnar part centered on the central axis J1. The second piston lower part 852 is connected to the lower end of the second piston upper part 851. The second piston upper part 851 and the second piston lower part 852 are preferably connected members. The second piston upper portion 851 protrudes radially outward from the outer surface of the second piston lower portion 852 over the entire circumference in the circumferential direction. In the example shown in FIGS. 3 and 4, the second piston lower part 852 is inserted inside the first piston 84, and the second piston upper part 851 is located above the first piston 84. The lower surface of the second piston upper portion 851 is in contact with the upper surface of the first piston upper portion 841.

  The second piston upper part 851 is arranged in the path upper part 801 of the movement path 80. In the state illustrated in FIG. 4, the second piston lower portion 852 is disposed over the upper path 801, the central path 802, and the lower path 803. The vertical length of the second piston lower part 852 is substantially the same as the vertical length of the first piston upper part 841.

  The diameters (that is, the outer diameters) of the second piston upper portion 851 and the second piston lower portion 852 are substantially the same over substantially the entire length in the vertical direction. The diameter of the second piston upper part 851 is larger than the diameter of the second piston lower part 852. The diameter of the second piston upper part 851 is larger than the inner diameter and the outer diameter of the first piston upper part 841.

  The diameter of the second piston upper part 851 is substantially the same as the diameter of the path upper part 801 of the movement path 80. The outer surface of the second piston upper portion 851 radially opposes the side surface of the path upper portion 801 with a very small gap therebetween. Driving oil is present in the gap. A plurality of second oil grooves 853 arranged at substantially equal intervals in the vertical direction are provided on the outer side surface of the second piston upper part 851. Each of the plurality of second oil grooves 853 is a circumferential recess provided over substantially the entire outer surface of the second piston upper part 851. Each second oil groove 853 holds the driving oil between the outer side surface of the second piston upper part 851 and the side surface of the path upper part 801. Thereby, sliding resistance generated between the second piston upper portion 851 and the hydraulic cylinder 81 is reduced.

  The diameter of the second piston lower part 852 is substantially the same as the inner diameter of the first piston upper part 841 and the second piston upper part 851. The outer surface of the second piston lower portion 852 radially opposes the inner surfaces of the first piston upper portion 841 and the first piston lower portion 842 (that is, the inner surface of the first piston 84) with a very small gap therebetween. I have. Driving oil is present in the gap. The diameter of the second piston lower part 852 is smaller than the diameter of the concave part 832 of the lower lid part 83.

  The second piston 85 further includes an upper convex portion 855 and a lower convex portion 856. The upper convex portion 855 protrudes upward from the center of the upper surface of the second piston upper portion 851. The lower convex portion 856 protrudes downward from the center of the lower surface of the second piston lower portion 852. The upper convex portion 855 and the lower convex portion 856 are preferably members that are connected to the second piston upper portion 851 and the second piston lower portion 852. Each of the upper convex portion 855 and the lower convex portion 856 is a substantially columnar protrusion centered on the central axis J1. The diameter of the upper convex portion 855 is substantially the same as the diameter of the upper opening 821. The diameter of the lower protrusion 856 is substantially the same as the diameter of the lower opening 831.

  The second piston 85 is movable between a bottom dead center indicated by a solid line in FIG. 3 and a top dead center indicated by a two-dot chain line. In a state where the second piston 85 is located at the bottom dead center, the substantially annular lower surface of the second piston upper portion 851 (that is, the substantially annular surface around the second piston lower portion 852) is in contact with the first piston upper portion 841. It contacts the upper surface of the substantially annular shape. The lower protrusion 856 projects downward from the lower end of the first piston 84 and is inserted into the lower opening 831 of the lower cover 83. A substantially annular lower surface of the second piston lower portion 852 (that is, a substantially annular surface around the lower convex portion 856) is substantially the same as the lower surface of the first piston lower portion 842 located at the bottom dead center in the vertical direction. Located in. The lower surface of the second piston lower portion 852 faces the lower lid portion 83 in the up-down direction with the above-described concave portion 832 interposed therebetween. The driving oil is present in the recess 832. As described above, since the diameter of the second piston lower portion 852 is smaller than the diameter of the concave portion 832, the lower surface of the second piston lower portion 852 does not directly contact the upper surface of the lower lid portion 83.

  When the second piston 85 is located at the top dead center, the upper protrusion 855 is inserted into the upper opening 821 of the upper cover 82. Further, the substantially annular upper surface of the second piston upper portion 851 (that is, the substantially annular surface around the upper convex portion 855) contacts the lower surface of the upper lid portion 82 around the upper opening 821. The lower surface of the second piston upper portion 851 is separated upward from the upper surface of the first piston upper portion 841 located at the top dead center. Therefore, a part of the second piston lower part 852 is exposed upward from the first piston 84.

  The hydraulic drive system 7 includes a first sensor 55, a second upper sensor 56, and a second lower sensor 57. The first sensor 55 measures the vertical position of the first piston 84 on the movement path 80 in a non-contact manner. The second upper sensor 56 and the second lower sensor 57 measure the vertical position of the second piston 85 on the movement path 80 in a non-contact manner. In the following description, the second upper sensor 56 and the second lower sensor 57 are also collectively referred to as a “second sensor”. The first sensor 55, the second upper sensor 56, and the second lower sensor 57 are, for example, capacitance type proximity sensors.

  The first sensor 55 is attached to the hydraulic cylinder 81 on the side of the path center 802. The second upper sensor 56 and the second lower sensor 57 are attached to the hydraulic cylinder 81 on the side of the upper path 801. The second lower sensor 57 is disposed below the second upper sensor 56. The first sensor 55, the second upper sensor 56, and the second lower sensor 57 are, for example, fixed to a hole extending radially outward from the movement path 80 in the hydraulic cylinder 81. The radial inner ends of the first sensor 55, the second upper sensor 56, and the second lower sensor 57 are located slightly radially outside the inner surface of the movement path 80.

  In the example shown in FIG. 3, the first sensor 55 is located above the uppermost first oil groove 843 of the first piston 84 located at the bottom dead center. The second upper sensor 56 is located at substantially the same position in the vertical direction as the lower end of the second piston upper part 851 located at the top dead center. The second lower sensor 57 is located at substantially the same vertical position as the upper end of the second piston upper part 851 located at the bottom dead center.

  The first sensor 55 measures the vertical position of the first piston 84 by detecting the vertical position of the plurality of first oil grooves 843 formed on the outer surface of the first piston upper part 841. Specifically, the number of the first oil grooves 843 that passed in front of the first sensor 55 is acquired by the first sensor 55, and the number of the first oil grooves 843 (that is, the output from the first sensor 55). The vertical position of the first piston 84 is determined by the position acquisition unit 63 (see FIG. 2) of the control system 6 based on Further, based on the number of first oil grooves 843 that have passed in front of the first sensor 55 and the time required to pass through the first oil grooves 843, the speed acquisition unit 64 of the control system 6 (see FIG. 2). The vertical velocity of the first piston 84 is determined.

  The second upper sensor 56 and the second lower sensor 57 detect the vertical position of the plurality of second oil grooves 853 formed on the outer surface of the second piston upper part 851, respectively. Measure the position in the direction. Specifically, the second upper sensor 56 and the second lower sensor 57 determine the number of the second oil grooves 853 passing in front of the second upper sensor 56 and the second oil groove 853 passing in front of the second lower sensor 57. The number of the oil grooves 853 is acquired, and the speed acquisition unit 64 moves the second piston 85 up and down based on the number of the second oil grooves 853 (ie, the outputs from the second upper sensor 56 and the second lower sensor 57). The position of the direction is determined. Also, based on the number of second oil grooves 853 that have passed in front of the second upper sensor 56 and the time required to pass through the second oil groove 853, a second piston that passes in front of the second upper sensor 56 The vertical speed 85 is obtained by the speed obtaining unit 64. In the speed acquisition unit 64, the vertical speed of the second piston 85 passing in front of the second lower sensor 57 also depends on the number of the second oil grooves 853 passing in front of the second lower sensor 57, and the second oil groove. 853 and the time required for the passage.

  Next, a normal operation of the hydraulic drive system 7 will be described with reference to FIGS. 5 to 10 are sectional views of the hydraulic drive system 7 during normal operation. 5 to 10, a partial configuration of the hydraulic drive system 7 is shown in a side view (the same applies to a sectional view described later). FIG. 11 is a diagram illustrating the vertical positions of the first piston 84 and the second piston 85 in the hydraulic drive system 7.

  The horizontal axis in FIG. 11 indicates the elapsed time from the rising start time (t0) of the first piston 84 and the second piston 85, and the vertical axis indicates that the bottom dead center of the first piston 84 and the second piston 85 is 0. 4 shows the vertical positions of the first piston 84 and the second piston 85 in the case of the above. 11, the solid line L1 indicates the vertical position of the first piston 84, and the broken line L2 indicates the vertical position of the second piston 85. The same applies to FIGS. 12, 17, 21 and 23. The dashed line L2 overlaps with the solid line L1 between times t0 and t1 and between times t4 and t5. The same applies to FIGS. 17, 21 and 23.

  FIG. 5 shows a state corresponding to time t0 in FIG. In the state shown in FIG. 5, the first piston 84 and the second piston 85 are located at the bottom dead center, and the lower surface of the first piston lower portion 842 is in contact with the lower lid 83 in the vertical direction. The lower surface of the second piston upper portion 851 is in contact with the upper surface of the first piston upper portion 841 in the up-down direction. In the following description, the vertical positions of the first piston 84 and the second piston 85 shown in FIG. 5 are also referred to as “lower end positions”. When the first piston 84 and the second piston 85 are located at the lower end positions, the exhaust valve 25 (see FIG. 1) connected to the hydraulic drive system 7 is closed. In the following description, the closed state of the exhaust valve 25 is also referred to as a “first state”, and the open state is also referred to as a “second state”.

  When shifting the exhaust valve 25 from the closed state to the open state (that is, from the first state to the second state), the first piston 84 and the second piston 85 move to the lower end position (that is, the bottom dead center). In the position, the solenoid valve 74 is controlled by the valve control unit 61 (see FIG. 2) of the control system 6, and the accumulator 75 and the hydraulic actuator 72 are connected. Thereby, as indicated by an arrow in FIG. 5, the driving oil in the accumulator 75 is sent to the hydraulic actuator 72 through the lower pipe 73 and the electromagnetic valve 74, and from the lower opening 831 of the hydraulic actuator 72 to the lower lid. It is supplied to the concave portion 832 of the portion 83.

  As described above, the concave portion 832 vertically faces the lower surface of the first piston 84 and the lower surface of the second piston 85 (that is, the lower surface of the lower portion 852 of the second piston). Therefore, an upward force is applied to the first piston 84 and the second piston 85 by the driving oil supplied to the concave portion 832, and the first piston 84 and the second piston 85 move upward integrally. In other words, both the first piston 84 and the second piston 85 move upward. As a result, the drive oil existing above the second piston 85 in the hydraulic cylinder 81 is supplied to the exhaust valve hydraulic cylinder 253 (see FIG. 1) via the hydraulic pipe 71 connected to the upper opening 821 of the hydraulic actuator 72. And a downward force (that is, a force for opening the exhaust valve 25) is transmitted to the exhaust valve 25 in the closed state. The driving oil supplied from the accumulator 75 to the lower opening 831 of the hydraulic actuator 72 flows into the movement path 80 of the hydraulic actuator 72 via the lower opening 831.

  Then, as shown in FIG. 6, the upper surface of the first piston lower portion 842 comes into contact with the upper end surface of the lower path portion 803, and the ascent of the first piston 84 stops. FIG. 6 shows a state corresponding to time t1 in FIG. In the state shown in FIG. 6, the first piston 84 is located at the top dead center, and the second piston 85 is in a state where the lower surface of the second piston upper part 851 is in contact with the upper surface of the first piston upper part 841. In the following description, the vertical positions of the first piston 84 and the second piston 85 shown in FIG. 6 are also referred to as “intermediate positions”. The first piston 84 is locked by the hydraulic cylinder 81 at the intermediate position. In other words, the first piston 84 stops at the intermediate position while being pressed against the hydraulic cylinder 81 from below.

  Thereafter, the second piston 85 moves further upward independently of the first piston 84 by the drive oil supplied from the accumulator 75 to the hydraulic actuator 72. Then, as shown in FIG. 7, the upper surface of the second piston upper part 851 comes into contact with the upper lid part 82, and the rising of the second piston 85 stops. At this time, a part of the second piston lower part 852 is exposed upward from the first piston 84. FIG. 7 shows a state corresponding to time t2 in FIG. In the state shown in FIG. 7, the first piston 84 is located at the top dead center (ie, the middle position), and the second piston 85 is also located at the top dead center. In the following description, the vertical position of the second piston 85 shown in FIG. 7 is also referred to as “upper end position”. The second piston 85 stops at the upper end position while being pressed against the upper lid portion 82 from below.

  When the second piston 85 is located at the upper end position, the upper protrusion 855 of the second piston 85 is inserted into the upper opening 821 of the upper cover 82. As described above, since the diameter of the upper convex portion 855 is substantially the same as the diameter of the upper opening 821, when the upper convex portion 855 is inserted into the upper opening 821, the inside of the upper opening 821 and the upper side of the upper opening 821. The drive oil existing on the hydraulic pipe 71 (i.e., on the hydraulic pipe 71 side) is suppressed from moving below the upper convex portion 855. As a result, the driving oil present in the upper opening 821 and above the upper opening 821 serves as a damper, and the rising speed of the second piston 85 when the upper convex portion 855 is inserted into the upper opening 821 is reduced. You. In other words, the slope of the broken line L2 in FIG. 11 becomes gentle immediately before time t2 as it approaches time t2. As a result, when the second piston 85 reaches the upper end position, the collision speed of the second piston 85 against the upper lid 82 can be reduced, and the force applied to the upper lid 82 due to the collision of the second piston 85 can be reduced. .

  In the diesel engine 1, as described above, the first piston 84 moves from the lower end position to the intermediate position, and the second piston 85 moves from the lower end position to the upper end position. Is delivered to the exhaust valve 25 (see FIG. 1) via the hydraulic pipe 71, and the exhaust valve 25 moves downward to be in an open state. Then, the positions of the first piston 84 and the second piston 85 are maintained for a predetermined time (that is, between times t2 and t3 in FIG. 11), so that the exhaust valve 25 is maintained in an open state. FIG. 7 also shows a state corresponding to times t2 to t3 in FIG.

  When the exhaust valve 25 is opened for a predetermined time, the closing of the exhaust valve 25 is started. When shifting the exhaust valve 25 from the open state to the closed state (that is, from the second state to the first state), the solenoid valve 74 is controlled by the valve control unit 61 (see FIG. 2), and the hydraulic actuator 72 is controlled. Is disconnected from the accumulator 75, and the lower opening 831 of the hydraulic actuator 72 is connected to the drain line. Thereby, as indicated by an arrow in FIG. 8, the drive oil in the movement path 80 of the hydraulic actuator 72 flows out from the lower opening 831 and flows out to the drain line via the lower pipe 73 and the solenoid valve 74. . FIG. 8 shows a state corresponding to time t3 in FIG.

  When the drive oil in the movement path 80 starts flowing to the drain line, the force of pressing the second piston 85 upward decreases, and the exhaust valve 25 moves upward by the air piston. As a result, a downward force is applied to the second piston 85 by the drive oil in the hydraulic pipe 71, and the second piston 85 moves downward from the upper end position (ie, top dead center). The driving oil sent from the hydraulic pipe 71 to the upper opening 821 of the hydraulic actuator 72 flows into the moving path 80 of the hydraulic actuator 72 via the upper opening 821.

  As shown in FIG. 9, the second piston 85 that moves downward from the upper end position contacts the first piston 84 at the above-described intermediate position in the up-down direction. Specifically, the lower surface of the second piston upper portion 851 contacts the upper surface of the first piston upper portion 841. FIG. 9 shows a state corresponding to time t4 in FIG. The second piston 85 further moves downward from the intermediate position together with the first piston 84 by the downward force applied by the driving oil flowing into the movement path 80 from the upper opening 821, as shown in FIG. It is located at the lower end position (that is, the bottom dead center). FIG. 10 shows a state corresponding to time t5 in FIG. At the lower end position, the first piston 84 is stationary in contact with the lower lid 83, and the second piston 85 is stationary in contact with the first piston 84.

  When the second piston 85 is located at the lower end position, the lower protrusion 856 of the second piston 85 is inserted into the lower opening 831 of the lower lid 83. At this time, the solenoid valve 74 disconnects the hydraulic actuator 72 from the drain line. As described above, since the diameter of the lower lid portion 83 is substantially the same as the diameter of the lower opening 831, when the lower convex portion 856 is inserted into the lower opening 831, the inside of the lower opening 831 and the lower opening portion 831 are lower. The drive oil existing on the side (ie, the lower pipe 73 side) plays the role of a damper, and the lowering speed of the second piston 85 when the lower convex portion 856 is inserted into the lower opening 831; The lowering speed of the first piston 84 moving integrally is reduced. In other words, the slopes of the solid line L1 and the broken line L2 in FIG. 11 become gentle just before time t5 and approach time t5. As a result, when the first piston 84 and the second piston 85 reach the lower end position, the collision speed of the first piston 84 with the lower lid 83 is reduced, and the first piston 84 collides with the lower lid 83. The force can be reduced.

  In the diesel engine 1, the positions of the first piston 84 and the second piston 85 (ie, the solid line L1 and the broken line L2 in FIG. 11) during the normal operation of the hydraulic actuator 72 are determined by the first sensor 55 and the second upper sensor 56. The position is acquired by the position acquisition unit 63 (see FIG. 2) based on the output from the second lower sensor 57 and is stored in the storage unit 65 in advance. In the storage unit 65, the time indicated on the horizontal axis in FIG. 11 is associated with the angle of the crank mechanism described above. In the diesel engine 1, the change in the speed of the first piston 84 and the second piston 85 during the normal operation of the hydraulic actuator 72 (that is, the change in the inclination of the solid line L1 and the broken line L2 in FIG. 11) is the first change. The speed is acquired by the speed acquisition unit 64 (see FIG. 2) based on the outputs from the sensor 55, the second upper sensor 56, and the second lower sensor 57, and is stored in the storage unit 65 in advance.

  In the following description, information on the positions of the first piston 84 and the second piston 85 during normal operation stored in the storage unit 65 is referred to as “reference position information”, and information on the speeds of the first piston 84 and the second piston 85 is referred to. The information is called “reference speed information”. The reference position information and the reference speed information may be, for example, in a graph format as shown in FIG. 11, or in another format such as a table format.

  In the diesel engine 1, when the hydraulic drive system 7 is driven, the measured values of the first sensor 55, the second upper sensor 56, and the second lower sensor 57 and the first piston stored in the storage unit 65 shown in FIG. The above-described reference position information and reference speed information of the second piston 85 and the second piston 85 are compared by the detection unit 62 of the control system 6. Specifically, based on the measurement values of the first sensor 55, the second upper sensor 56, and the second lower sensor 57, the position information of the first piston 84 and the second piston 85 is obtained by the position acquisition unit 63 and the speed acquisition unit 64. And speed information. Then, the detection unit 62 compares the position information and the speed information (hereinafter, referred to as “measured position information” and “measured speed information”) with the reference position information and the reference speed information.

  When the deviation of the measured position information from the reference position information is larger than the allowable range, the detecting unit 62 determines that the hydraulic actuator 72 has an abnormal position of the piston. If the deviation of the measured speed information from the reference speed information is larger than the allowable range, it is determined that the hydraulic actuator 72 has a piston speed abnormality.

  Thus, in the diesel engine 1, the monitoring unit 67 that monitors the operation of the hydraulic actuator 72 is configured by the detecting unit 62, the first sensor 55, the second upper sensor 56, and the second lower sensor 57. Further, the operation of the hydraulic actuator 72 is performed by the monitoring unit 67, the hydraulic actuator 72, and the above-described drive control unit 66 (ie, the solenoid valve 74 and the valve control unit 61) that controls the flow of the drive oil in the hydraulic actuator 72. A monitoring system is configured. Note that the monitoring unit 67 may include a position acquisition unit 63. Further, the monitoring section 67 may include a speed acquisition section 64.

  Next, a specific example of detection of an abnormal operation of the hydraulic actuator 72 by the operation monitoring system will be described. FIG. 12 is an enlarged view of a part of the diagram showing the vertical positions of the first piston 84 and the second piston 85 when the rising delay of the first piston 84 occurs. 13 to 16 are cross-sectional views showing the operation of the hydraulic drive system 7 when a delay in raising the first piston 84 occurs.

  FIG. 13 shows a state corresponding to time t0 in FIG. In the state shown in FIG. 13, similarly to the state shown in FIG. 5, the first piston 84 and the second piston 85 are located at the lower end position (that is, the bottom dead center), and the lower surface of the first piston lower part 842 is It is in contact with the lower lid 83 in the vertical direction. The lower surface of the second piston upper portion 851 is in contact with the upper surface of the first piston upper portion 841 in the up-down direction. When the first piston 84 and the second piston 85 are located at the lower end positions, the exhaust valve 25 (see FIG. 1) connected to the hydraulic drive system 7 is closed.

  When shifting the exhaust valve 25 from the closed state to the open state (that is, from the first state to the second state), as described above, the driving oil in the accumulator 75 causes the lower pipe 73 and the solenoid valve 74 to move. Through the lower opening 831 of the hydraulic actuator 72 to the recess 832 of the lower lid 83. When the hydraulic actuator 72 operates normally, as described above, the first piston 84 and the second piston 85 are pushed upward by the driving oil supplied to the concave portion 832, and the first piston 84 and the second piston 85 The upward movement is started at the same time.

  However, if the driving oil pushes the first piston 84 upward for some reason is insufficient, an abnormality may occur in which the second piston 85 starts moving upward from the lower end position before the first piston 84. There is. The cause may be, for example, a shortage of the area of the lower surface of the first piston lower portion 842 that faces the concave portion 832 in the vertical direction, or poor sliding between the first piston 84 and the hydraulic cylinder 81. . The sliding failure is caused, for example, by an increase in sliding resistance due to a shortage of driving oil between the outer surface of the first piston upper portion 841 and the inner surface of the path central portion 802 and a bite of a foreign object.

  As described above, when the ascent of the second piston 85 is started first, as shown in FIG. 14, the upper part 851 of the second piston separates upward from the upper surface of the first piston 84, and the lower part 852 of the second piston 85 The upper part is exposed from the first piston 84, after which the first piston 84 starts to rise. FIG. 14 shows a state corresponding to time t11 in FIG. In the state shown in FIG. 14, the rise of the second piston 85 causes the drive oil existing above the second piston 85 in the hydraulic cylinder 81 to flow to the hydraulic pipe 71 and the exhaust valve hydraulic cylinder 253 (see FIG. 1). It is performed while sending. In other words, the second piston 85 is raised while receiving the resistance of the driving oil inside the hydraulic pipe 71 and the like, and the resistance of the air piston and the like against opening of the exhaust valve 25.

  On the other hand, the first piston 84 is raised almost without receiving the resistance, so that the rising speed of the first piston 84 is higher than the rising speed of the second piston 85. As a result, as shown in FIG. 15, below the intermediate position, the first piston 84 catches up with the second piston 85 and collides from below. Specifically, the upper surface of the first piston upper portion 841 collides with the lower surface of the second piston upper portion 851. FIG. 15 shows a state corresponding to time t12 in FIG. Thereafter, the first piston 84 and the second piston 85 rise integrally, and are located at the intermediate position as shown in FIG. 16 (time t1).

  When the above-described abnormality of the hydraulic actuator 72 (that is, the collision between the first piston 84 and the second piston 85 due to the delay in raising the first piston 84) occurs, the first piston 84 and the second piston 85 each time the exhaust valve 25 is opened and closed. The collision with the two pistons 85 is repeated, and the impact due to the collision is repeatedly transmitted to other components via driving oil or the like. As a result, a problem may occur in the configuration of the hydraulic drive system 7 such as the first piston 84 and the second piston 85, or the electromagnetic valve 74 and the accumulator 75, and an abnormal operation of the exhaust valve 25 may occur. However, only the operation monitoring of the exhaust valve 25 cannot detect the abnormality of the hydraulic actuator 72 until the abnormality of the operation of the exhaust valve 25 occurs. Therefore, it is difficult to prevent the abnormality of the operation of the exhaust valve 25.

  Therefore, in the monitoring unit 67 of the diesel engine 1 shown in FIG. 2, the detection unit 62 of the control system 6 performs the measurement shown in FIG. 12 based on the outputs from the first sensor 55, the second upper sensor 56, and the second lower sensor 57. By comparing the position information with the reference position information shown in FIG. 11, it is detected that the hydraulic actuator 72 has an abnormality such as a delay in raising the first piston 84. The abnormality detected by the detection unit 62 (that is, the delay in raising the first piston 84) is notified by the control system 6 to the operator by a warning sound, a warning display, or the like. As a result, the abnormality of the hydraulic actuator 72 can be detected at an early stage, and the operation abnormality of the exhaust valve 25 can be prevented or suppressed.

  FIG. 17 is an enlarged view of a part of the diagram showing the vertical positions of the first piston 84 and the second piston 85 when the seating failure of the first piston 84 and the second piston 85 occurs. In FIG. 17, the positions of the first piston 84 and the second piston 85 during the normal operation are indicated by a two-dot chain line L3. 18 to 20 are cross-sectional views showing the operation of the hydraulic drive system 7 when the seating failure of the first piston 84 and the second piston 85 occurs.

  FIG. 18 shows a state corresponding to time t3 in FIG. In the state shown in FIG. 18, the first piston 84 is located at the intermediate position, and the second piston 85 is located at the upper end position, as in the state shown in FIG. Further, the exhaust valve 25 (see FIG. 1) connected to the hydraulic drive system 7 is in an open state.

  When shifting the exhaust valve 25 from the open state to the closed state (that is, from the second state to the first state), the hydraulic valve 72 is connected to the drain actuator by the solenoid valve 74 as described above, The drive oil in the movement path 80 of the hydraulic actuator 72 flows out from the lower opening 831 to the drain line. As a result, the second piston 85 moves downward from the upper end position and contacts the first piston 84 at the intermediate position in the vertical direction as shown in FIG. Specifically, the lower surface of the second piston upper portion 851 contacts the upper surface of the first piston upper portion 841. FIG. 19 shows a state corresponding to time t4 in FIG.

  Then, the second piston 85 is further pushed downward by the drive oil flowing into the movement path 80 from the upper opening 821, and the second piston 85 moves downward from the intermediate position together with the first piston 84. When the hydraulic actuator 72 operates normally, as described above, the first piston 84 and the second piston 85 move downward from the intermediate position and reach the lower end position.

  However, when the driving oil pushes down the second piston 85 downward due to some cause, the descent speed from the intermediate position between the first piston 84 and the second piston 85 (that is, at the time t4 to t5 in FIG. 17). (The slope of the solid line L1) is smaller than the reference state indicated by the two-dot chain line L3. As a result, as shown in FIG. 20, the first piston 84 and the second piston 85 do not reach the lower end position but stop above the lower end position (for example, between the intermediate position and the lower end position) ( That is, seating failure) may occur. FIG. 20 shows a state corresponding to time t5 in FIG. The cause may be, for example, poor sliding between the first piston 84 and the hydraulic cylinder 81. The sliding failure is caused, for example, by an increase in sliding resistance due to a shortage of driving oil between the outer surface of the first piston upper portion 841 and the inner surface of the path central portion 802 and a bite of a foreign object. When the seating failure occurs, the next valve opening operation may be started before the valve closing operation of the exhaust valve 25 is completed.

  In the monitoring unit 67 shown in FIG. 2, the detection unit 62 of the control system 6 uses the measurement position information shown in FIG. 17 based on the outputs from the first sensor 55, the second upper sensor 56, and the second lower sensor 57, and FIG. By comparing with the reference position information shown in (1), it is detected that an abnormality such as a seating failure of the first piston 84 and the second piston 85 occurs in the hydraulic actuator 72. The abnormality detected by the detection unit 62 (that is, the poor seating of the first piston 84 and the second piston 85) is notified by the control system 6 to the operator by an alarm sound or a warning display. As a result, the abnormality of the hydraulic actuator 72 can be detected at an early stage, and the operation abnormality of the exhaust valve 25 can be prevented or suppressed.

  The seating failure between the first piston 84 and the second piston 85 may occur due to a cause other than the above-described sliding failure between the first piston 84 and the hydraulic cylinder 81. For example, the second piston 85 moves from the exhaust valve 25 to the second piston 85 due to poor sliding between the second piston 85 and the hydraulic cylinder 81 or air entrapment in the hydraulic pipe 71 or the like (that is, air bubbles mixed into the driving oil). May be insufficient due to insufficient transmission of the power of the driving oil or the like. In this case, the descending speed of the second piston 85 from the upper end position to the intermediate position (that is, the inclination of the broken line L2 between times t3 and t4 in FIG. 17) is also smaller than the reference state. Even in this case, the seating failure of the first piston 84 and the second piston 85 is detected by the detection unit 62, and the abnormal operation of the exhaust valve 25 is prevented or suppressed.

  FIG. 21 is an enlarged view of a part of the diagram showing the vertical positions of the first piston 84 and the second piston 85 when the upper damper failure of the second piston 85 occurs. In FIG. 21, the position of the second piston 85 during normal operation is indicated by a two-dot chain line L3. FIG. 22 is a sectional view showing the state of the hydraulic drive system 7 immediately before time t2 in FIG.

  In the state shown in FIG. 22, the first piston 84 is located at the intermediate position, and the second piston 85 is immediately before reaching the upper end position. More specifically, the second piston 85 is rising near the upper end position between the intermediate position and the upper end position, and the upper protrusion 855 of the second piston 85 is inserted into the upper opening 821 of the upper lid 82. Has begun. When the hydraulic actuator 72 operates normally, as described above, the driving oil present in the upper opening 821 and above the upper opening 821 (that is, on the hydraulic pipe 71 side) serves as a damper, and the second piston The rising speed of 85 is reduced as shown by the two-dot chain line L3 in FIG.

  However, when the driving oil existing in the upper opening 821 and above the upper opening 821 does not sufficiently function as a damper for some reason, the rising speed of the second piston 85 near the upper end position is not reduced so much, and The piston 85 may collide with the upper lid 82 at a relatively high speed. The cause may be, for example, that the diameter of the upper convex portion 855 is excessively smaller than the diameter of the upper opening 821.

  When the above-described abnormality of the hydraulic actuator 72 (that is, the abnormality of the speed of the second piston 85 near the upper end position due to the failure of the upper damper) occurs, each time the exhaust valve 25 is opened and closed, the comparison between the second piston 85 and the upper lid portion 82 is performed. The collision at an extremely high speed is repeated, and the impact due to the collision is repeatedly transmitted to other components via driving oil or the like. As a result, a problem may occur in the configuration of the hydraulic drive system 7 such as the upper lid portion 82, the second piston 85, or the electromagnetic valve 74 and the accumulator 75, and a malfunction of the exhaust valve 25 may occur.

  In the monitoring unit 67 shown in FIG. 2, based on the output from the second upper sensor 56, the speed of the second piston 85 when the upper protrusion 855 is inserted into the upper opening 821 is determined by the speed acquisition unit 64 of the control system 6. The ascending speed (hereinafter, referred to as “upper insertion speed”) is acquired. The upper insertion speed is included in the above-described measured speed information. The detection unit 62 determines the upper insertion speed acquired by the speed acquisition unit 64 (that is, the inclination of the broken line L2 immediately before time t2 in FIG. 21) and the upper insertion speed of the second piston 85 during normal operation of the hydraulic actuator 72 ( That is, by comparing with the inclination of the two-dot chain line L3 immediately before the time t2, it is detected that the hydraulic actuator 72 has an abnormal speed of the second piston 85 near the upper end position due to the upper damper failure. The abnormality detected by the detector 62 (that is, the upper damper failure) is notified to the operator by the control system 6 by an alarm sound, a warning display, or the like. As a result, the abnormality of the hydraulic actuator 72 can be detected at an early stage, and the operation abnormality of the exhaust valve 25 can be prevented or suppressed.

  FIG. 23 is an enlarged view of a part of the diagram showing the vertical positions of the first piston 84 and the second piston 85 when the lower damper failure of the second piston 85 occurs. In FIG. 23, the position of the second piston 85 during normal operation is indicated by a two-dot chain line L3. FIG. 24 is a sectional view showing the state of the hydraulic drive system 7 immediately before time t5 in FIG.

  In the state shown in FIG. 24, the first piston 84 and the second piston 85 are just before reaching the lower end position. Specifically, the first piston 84 and the second piston 85 are descending integrally near the lower end position between the intermediate position and the lower end position, and the lower protrusion 856 of the second piston 85 is It has begun to be inserted into the lower opening 831 of the part 83. When the hydraulic actuator 72 operates normally, as described above, the driving oil present in the lower opening 831 and below the lower opening 831 (that is, on the lower pipe 73 side) serves as a damper, and The descending speeds of the piston 84 and the second piston 85 are reduced as shown by a two-dot chain line L3 in FIG.

  However, when the driving oil existing in the lower opening 831 and below the lower opening 831 does not sufficiently function as a damper for some reason, the descending speeds of the first piston 84 and the second piston 85 near the lower end position are not so high. Without being reduced, the first piston 84 may collide with the lower lid 83 at a relatively high speed. The cause may be, for example, that the diameter of the lower protrusion 856 is excessively smaller than the diameter of the lower opening 831.

  When the above-described abnormality of the hydraulic actuator 72 (that is, the abnormal velocity of the first piston 84 and the second piston 85 near the lower end position due to the lower damper failure) occurs, the first piston 84 and the lower piston The collision with the lid 83 at a relatively high speed is repeated, and the impact due to the collision is repeatedly transmitted to other components via driving oil or the like. As a result, a problem may occur in the configuration of the hydraulic drive system 7 such as the lower lid 83 and the first piston 84, or the electromagnetic valve 74 and the accumulator 75, and an abnormal operation of the exhaust valve 25 may occur.

  In the monitoring unit 67 shown in FIG. 2, based on the output from the first sensor 55, the first piston 84 and the first piston 84 when the lower convex portion 856 is inserted into the lower opening 831 by the speed acquisition unit 64 of the control system 6. The lowering speed of the two pistons 85 (hereinafter, referred to as “lower insertion speed”) is obtained. The lower insertion speed is included in the above-described measured speed information. The detecting unit 62 determines the lower insertion speed (that is, the inclination of the solid line L1 (and the broken line L2) immediately before time t5 in FIG. 23) acquired by the speed acquiring unit 64 and the first piston 84 during normal operation of the hydraulic actuator 72. And the lower insertion speed of the second piston 85 (that is, the inclination of the two-dot chain line L3 immediately before the time t5), the first piston 84 and the second piston 84 in the vicinity of the lower end position due to the lower damper failure in the hydraulic actuator 72. It is detected that a speed abnormality of 85 has occurred. The abnormality detected by the detection unit 62 (that is, the lower damper failure) is notified to the operator by the control system 6 by an alarm sound or a warning display. As a result, the abnormality of the hydraulic actuator 72 can be detected at an early stage, and the operation abnormality of the exhaust valve 25 can be prevented or suppressed.

  As described above, the operation monitoring system of the hydraulic actuator 72 provided on the hydraulic drive line of the diesel engine 1 includes the hydraulic actuator 72, the drive control unit 66, and the monitoring unit 67. The hydraulic actuator 72 is connected to a drive target via a hydraulic pipe 71. The drive control unit 66 controls the flow of the drive oil in the hydraulic actuator 72. The monitoring unit 67 monitors the operation of the hydraulic actuator 72. The hydraulic actuator 72 includes a tubular hydraulic cylinder 81, an upper cover 82, a lower cover 83, a first piston 84, and a second piston 85. The hydraulic cylinder 81 has a cylindrical moving path 80 that faces in the up-down direction inside. The upper lid 82 closes the upper end of the movement path 80. The upper lid portion 82 has an upper opening 821 smaller in diameter than the movement path 80. The lower lid 83 closes the lower end of the movement path 80. The lower lid 83 has a lower opening 831 having a smaller diameter than the moving path 80. The first piston 84 moves up and down in the movement path 80. The second piston 85 moves up and down in the movement path 80. The second piston 85 is inserted inside the first piston 84.

  When the drive target is shifted from the first state to the second state (for example, when the exhaust valve 25 is shifted from the closed state to the open state), the drive control unit 66 controls the lower opening 831. The driving oil flows into the moving path 80 from. The first piston 84 and the second piston 85 move upward from the lower end position, the first piston 84 is locked by the hydraulic cylinder 81 at the intermediate position, and the second piston 85 moves further upward to the upper end. Located to the position. Due to the above-described movement of the first piston 84 and the second piston 85, the driving oil is delivered to the driven object via the hydraulic pipe 71 connected to the upper opening 821. At the lower end position, the first piston 84 contacts the lower lid 83, and the second piston 85 contacts the first piston 84 in the up-down direction. At the upper end position, the second piston 85 contacts the upper lid portion 82.

  When the drive target is shifted from the second state to the first state (for example, when the exhaust valve 25 is shifted from the open state to the closed state), the drive control unit 66 controls the lower opening 831. The driving oil of the moving path 80 flows out of the vehicle. The second piston 85 moves from the upper end position to the intermediate position, contacts the first piston 84 in the vertical direction, and moves from the intermediate position to the lower end position together with the first piston 84.

  The monitoring unit 67 includes a first sensor 55, a second sensor (that is, a second upper sensor 56 and / or a second lower sensor 57), and a detection unit 62. The first sensor 55 measures the position of the first piston 84 in the movement path 80 in a non-contact manner. The second sensor measures the position of the second piston 85 on the movement path 80 in a non-contact manner. The detection unit 62 detects the abnormality of the hydraulic actuator 72 by comparing the positions of the first piston 84 and the second piston 85 during the normal operation of the hydraulic actuator 72 with the measured values of the first sensor 55 and the second sensor. I do.

  According to the operation monitoring system, the position of the first piston 84 and the second piston 85 of the hydraulic actuator 72 is monitored using the first sensor 55 and the second sensor, so that the abnormality of the hydraulic actuator 72 is automatically determined. Can be detected. As a result, it is possible to prevent or suppress the operation abnormality of the driven object caused by the abnormality of the hydraulic actuator 72.

  As described above, the drive target of the hydraulic actuator 72 is preferably the exhaust valve 25 of the diesel engine 1. Thus, it is possible to prevent or suppress the operation abnormality of the exhaust valve 25 caused by the abnormality of the hydraulic actuator 72.

  Preferably, a plurality of circumferentially arranged first oil grooves 843 are provided on the side surface of the first piston 84, and the first oil grooves 843 are arranged on the side surface of the second piston 85, respectively. Are provided with a plurality of second oil grooves 853 having a circumferential shape. The first sensor 55 measures the position of the first piston 84 by detecting the vertical position of the plurality of first oil grooves 843, and the second sensor measures the position of the plurality of second oil grooves 853. It is preferable to measure the position of the second piston 85 by detecting the position in the vertical direction. As described above, by detecting the position using the oil groove for reducing the sliding resistance of the first piston 84 and the second piston 85, the shape of the first piston 84 and the second piston 85 is not changed. , The vertical position of the first piston 84 and the second piston 85 can be easily and accurately detected.

  In the monitoring section 67, the first sensor 55 is preferably located above the plurality of first oil grooves 843 of the first piston 84 located at the lower end position. This makes it possible to suitably detect the position of the first piston 84 using the first oil groove 843.

  In the monitoring unit 67, it is more preferable that a second upper sensor 56 and a second lower sensor 57 are provided as the second sensors. The second lower sensor 57 is disposed below the second upper sensor 56. The second upper sensor 56 and the second lower sensor 57 each measure the position of the second piston 85 by detecting the position of the plurality of second oil grooves 853 in the vertical direction. Thereby, the accuracy of the position detection of the second piston 85 can be improved.

  The second upper sensor 56 is located above the plurality of second oil grooves 853 of the second piston 85 located at the intermediate position, and is located above the plurality of second oil grooves 853 of the second piston 85 located at the upper end position. It is preferably located on the lower side. Further, the second lower sensor 57 is located above the plurality of second oil grooves 853 of the second piston 85 located at the intermediate position, and the plurality of second oil grooves 853 of the second piston 85 located at the upper end position. It is preferably located below. This makes it possible to suitably detect the position of the second piston 85 using the second oil groove 853.

  In the above operation monitoring system, the abnormality detected by the detection unit 62 is described as follows: “When the above-mentioned driven object is shifted from the first state to the second state, the lower end of the second piston 85 is moved ahead of the first piston 84. It is preferable that the first piston 84 starts moving upward from the position and the first piston 84 collides with the second piston 85 below from below the intermediate position. According to the operation monitoring system, such a delay in raising the first piston 84 and a collision between the first piston 84 and the second piston 85 due to the delay in rising can be automatically detected. As a result, it is possible to prevent or suppress the operation abnormality of the driven object due to the delay in raising the first piston 84.

  In the operation monitoring system, the abnormality detected by the detection unit 62 includes "an abnormality in which the first piston 84 and the second piston 85 do not reach the lower end position when moving downward from the intermediate position". Is preferred. According to the operation monitoring system, such a seating failure of the first piston 84 and the second piston 85 can be automatically detected. As a result, it is possible to prevent or suppress the operation abnormality of the driven object due to the poor seating.

  In the operation monitoring system, preferably, the upper convex portion 855 protrudes upward from the upper surface of the second piston 85. The upper convex portion 855 is inserted into the upper opening 821 in a state where the second piston 85 is located at the upper end position. It is preferable that the monitoring unit 67 further includes a speed acquisition unit 64 that acquires the upper insertion speed of the second piston 85 when the upper convex portion 855 is inserted into the upper opening 821. The detection unit 62 compares the upper insertion speed acquired by the speed acquisition unit 64 with the upper insertion speed of the second piston 85 during normal operation of the hydraulic actuator 72, and compares the speed of the second piston 85 near the upper end position. It is preferable to detect an abnormality. According to the operation monitoring system, the above-described defective upper damper and an excessive collision between the second piston 85 and the upper lid portion 82 due to the defective upper damper can be automatically detected. As a result, it is possible to prevent or suppress the abnormal operation of the driven object due to the defective upper damper.

  In the operation monitoring system, preferably, the lower convex portion 856 protrudes downward from the lower surface of the second piston 85. The lower protruding portion 856 is inserted into the lower opening 831 in a state where the second piston 85 is located at the lower end position. It is preferable that the monitoring unit 67 further includes a speed acquisition unit 64 that acquires the downward insertion speed of the second piston 85 when the lower convex portion 856 is inserted into the lower opening 831. The detection unit 62 compares the lower insertion speed acquired by the speed acquisition unit 64 with the lower insertion speed of the second piston 85 during normal operation of the hydraulic actuator 72, and compares the speed of the second piston 85 near the lower end position. It is preferable to detect an abnormality. According to the operation monitoring system, the above-described defective lower damper and an excessive collision between the first piston 84 and the lower lid 83 due to the defective lower damper can be automatically detected. As a result, it is possible to prevent or suppress the operation abnormality of the driven object due to the lower damper defect.

  Various changes are possible in the operation monitoring system and the diesel engine 1 described above.

  For example, the plurality of first oil grooves 843 need not necessarily be arranged at equal intervals. Similarly, the plurality of second oil grooves 853 need not necessarily be arranged at equal intervals.

  The first sensor 55, the second upper sensor 56, and the second lower sensor 57 are not limited to capacitance type proximity sensors, and are sensors that can measure the vertical positions of the first piston 84 and the second piston 85. If so, a sensor having another structure (for example, an optical sensor) may be used.

  The first sensor 55 does not necessarily need to detect the vertical position of the plurality of first oil grooves 843, and the second upper sensor 56 and the second lower sensor 57 do not necessarily detect the vertical position of the plurality of second oil grooves 853. There is no need to detect the position of. For example, the outer surface of the first piston upper portion 841 is an inclined surface whose outer diameter gradually decreases from one side in the up-down direction to the other side, and the first sensor 55 has a radial distance to the outer surface. , The vertical position of the first piston 84 may be measured. The inclined surface may be provided only on a portion other than the plurality of first oil grooves 843 on the outer surface of the first piston upper portion 841 provided with the plurality of first oil grooves 843.

  Further, for example, the outer surface of the second piston upper part 851 is an inclined surface whose outer diameter gradually decreases as going from one side in the vertical direction to the other side, and the second upper sensor 56 and the second lower sensor 57 The vertical position of the second piston 85 may be measured by measuring the radial distance to the outer surface. Note that the inclined surface may be provided only in a portion other than the plurality of second oil grooves 853 on the outer surface of the second piston upper portion 851 provided with the plurality of second oil grooves 853.

  In the monitoring unit 67, one of the second upper sensor 56 and the second lower sensor 57 may be omitted, and the vertical position of the second piston 85 may be measured only by the other second sensor. .

  The shapes of the first piston 84 and the second piston 85 are not limited to the examples described above, and may be variously changed. For example, the upper protrusion 855 may be omitted from the second piston 85, and the lower protrusion 856 may be omitted.

  In the hydraulic drive system 7a shown in FIG. 25, the hydraulic actuator 72a includes a substantially cylindrical hydraulic cylinder 81a, an upper cover 82a, a lower cover 83a, a substantially cylindrical first piston 84a, and a substantially cylindrical shape. And a second piston 85a. The moving path 80a inside the hydraulic cylinder 81a includes a substantially cylindrical path upper part 801a and a substantially cylindrical path lower part 803a. The diameter (that is, the inner diameter) of the upper path 801a is smaller than the diameter of the lower path 803a.

  The first piston 84a is disposed in the lower path portion 803a. The first piston 84a includes a substantially cylindrical first piston upper portion 841a and a substantially cylindrical first piston lower portion 842a. The inner diameter of the first piston upper part 841a is larger than the inner diameter of the first piston lower part 842a. The outer diameter of the first piston upper part 841a and the outer diameter of the first piston lower part 842a are substantially the same, and the diameter of the path lower part 803a is also substantially the same. The first piston 84a located at the lower end position shown by the solid line in FIG. 25 is in contact with the lower lid 83a in the up-down direction.

  The second piston 85a includes a substantially cylindrical second piston upper portion 851a, a substantially cylindrical second piston lower portion 852a, an upper convex portion 855a, and a lower convex portion 856a. The outer diameter of the second piston upper part 851a is substantially the same as the inner diameter of the first piston upper part 841a, and is also substantially the same as the diameter of the path upper part 801a. The outer diameter of the second piston lower part 852a is smaller than the outer diameter of the second piston upper part 851a, and is substantially the same as the inner diameter of the first piston lower part 842a. In the second piston 85a located at the lower end position indicated by the solid line in FIG. 25, substantially the entirety is inserted inside the first piston 84a. In the second piston 85a located at the lower end position, only the upper protrusion 855a and the lower protrusion 856a protrude above and below the first piston 84a.

  The first piston 84a is vertically movable between the lower end position described above and an intermediate position indicated by a two-dot chain line in FIG. The upper surface of the first piston 84a located at the intermediate position contacts the upper end surface of the lower path 803a in the vertical direction. The second piston 85a is vertically movable between the above-described lower end position and the upper end position indicated by a two-dot chain line in FIG. The upper surface of the second piston 85a located at the upper end position contacts the lower surface of the upper lid portion 82a in the vertical direction.

  In the hydraulic actuator 72a, the vertical position of the first piston 84a is measured by the first sensor 55a fixed to the hydraulic cylinder 81a on the side of the lower path 803a. Further, the vertical position of the second piston 85a is measured by the second sensor 56a fixed to the hydraulic cylinder 81a on the side of the upper path 801a. Then, the position of the first piston 84a and the second piston 85a during the normal operation of the hydraulic actuator 72a and the measured values of the first sensor 55a and the second sensor 56a are compared by the detecting unit 62 (see FIG. 2). The abnormality of the hydraulic actuator 72a is detected. Thereby, similarly to the above, the abnormality of the hydraulic actuator 72a can be automatically detected.

  The abnormality of the hydraulic actuator 72 detected by the detection unit 62 shown in FIG. 2 includes the above-described delay in raising the first piston 84, poor seating of the first piston 84 and the second piston 85, defective upper damper, and defective lower damper. However, other abnormalities may be detected. The same applies to the hydraulic actuator 72a.

  The drive target of the hydraulic actuators 72 and 72a is not necessarily limited to the exhaust valve 25, but may be another configuration (for example, a fuel supply pump) of the diesel engine 1.

  The diesel engine 1 is not limited to a two-stroke engine, but may be a four-stroke engine. Further, the above-described operation monitoring system may be provided in various diesel engines such as a power generation diesel engine or an automobile diesel engine, in addition to a diesel engine used as a main engine of a ship.

  The configurations in the above embodiment and each modified example may be appropriately combined as long as they do not conflict with each other.

Reference Signs List 1 diesel engine 25 exhaust valve 55, 55a first sensor 56 second upper sensor 56a second sensor 57 second lower sensor 62 detecting unit 63 position obtaining unit 64 speed obtaining unit 66 drive control unit 67 monitoring unit 71 hydraulic piping 72, 72a Hydraulic actuator 80, 80a Movement path 81, 81a Hydraulic cylinder 82, 82a Upper lid 83, 83a Lower lid 84, 84a First piston 85, 85a Second piston 821 Upper opening 831 Lower opening 843 First oil groove 853 Second oil Groove 855, 855a Upper convex part 856, 856a Lower convex part

Claims (7)

An operation monitoring system of a hydraulic actuator provided in a hydraulic drive line of a diesel engine,
A hydraulic actuator connected to the driven object via a hydraulic pipe,
A drive control unit that controls the flow of drive oil in the hydraulic actuator,
A monitoring unit that monitors the operation of the hydraulic actuator,
With
The hydraulic actuator,
A cylindrical hydraulic cylinder having a cylindrical moving path facing in the vertical direction inside,
An upper lid portion that closes an upper end of the moving path and has an upper opening with a smaller diameter than the moving path,
A lower lid portion that closes a lower end of the moving path and has a lower opening with a smaller diameter than the moving path,
A first cylindrical piston that moves vertically in the movement path;
A second piston that moves up and down in the movement path and is inserted inside the first piston;
With
When shifting the drive target from the first state to the second state, the drive control unit causes the drive oil to flow into the movement path from the lower opening, and the first piston and the second piston are The first piston comes into contact with the lower lid and moves upward from a lower end position where the second piston comes into contact with the first piston in a vertical direction. The second piston is further moved upward and is located at an upper end position in contact with the upper lid portion, and is connected to the upper opening by the movement of the first piston and the second piston. The driving oil is delivered to the driven object through the hydraulic pipe,
When shifting the drive target from the second state to the first state, the drive control unit causes the drive oil of the movement path to flow out of the lower opening, and the second piston is moved from the upper end position. Moving to the intermediate position, vertically contacting the first piston, and moving from the intermediate position to the lower end position together with the first piston;
The monitoring unit is
A first sensor that measures the position of the first piston in the movement path in a non-contact manner;
A second sensor that measures the position of the second piston in the movement path in a non-contact manner;
A detecting unit that compares the positions of the first piston and the second piston during normal operation of the hydraulic actuator with measured values of the first sensor and the second sensor to detect an abnormality of the hydraulic actuator; ,
An operation monitoring system comprising: The operation monitoring system according to claim 1, wherein
The operation monitoring system is characterized in that the drive target is an exhaust valve of a diesel engine. The operation monitoring system according to claim 1 or 2,
On the side surface of the first piston, a plurality of first oil grooves each arranged in a vertical direction are provided,
A plurality of circumferentially arranged second oil grooves are provided on a side surface of the second piston.
The first sensor measures a position of the first piston by detecting a vertical position of the plurality of first oil grooves,
The operation monitoring system according to claim 2, wherein the second sensor measures a position of the second piston by detecting a vertical position of the plurality of second oil grooves. The operation monitoring system according to any one of claims 1 to 3, wherein
The abnormality detected by the detection unit is:
When shifting the driven object from the first state to the second state, the second piston starts moving upward from the lower end position earlier than the first piston, and moves upward from the intermediate position. An operation monitoring system comprising an abnormality in which the first piston collides with the second piston from below on a lower side. The operation monitoring system according to any one of claims 1 to 4,
The abnormality detected by the detection unit is:
An operation monitoring system characterized by including an abnormality that does not reach the lower end position when the first piston and the second piston move downward from the intermediate position. The operation monitoring system according to any one of claims 1 to 5,
An upper projection inserted into the upper opening in a state where the second piston is located at the upper end position projects upward from an upper surface of the second piston,
The monitoring unit further includes a speed acquisition unit that acquires an upper insertion speed of the second piston when the upper protrusion is inserted into the upper opening,
The detection unit compares the upper insertion speed acquired by the speed acquisition unit with the upper insertion speed of the second piston during normal operation of the hydraulic actuator, and compares the second piston near the upper end position with the second piston. An operation monitoring system characterized by detecting a speed abnormality of a vehicle. The operation monitoring system according to any one of claims 1 to 6,
A lower convex portion inserted into the lower opening in a state where the second piston is located at the lower end position projects downward from a lower surface of the second piston,
The monitoring unit further includes a speed acquisition unit that acquires a downward insertion speed of the second piston when the lower protrusion is inserted into the lower opening,
The detection unit compares the lower insertion speed acquired by the speed acquisition unit with the lower insertion speed of the second piston during a normal operation of the hydraulic actuator, and compares the lower insertion speed with the second piston near the lower end position. An operation monitoring system characterized by detecting a speed abnormality of a vehicle.

Images