Gas fuel distribution system and engine

Abstract

This technology provides the ability to detect the state of gaseous fuel flowing through the inner pipe and to prevent leakage of gaseous fuel outside the outer pipe. [Solution] The gaseous fuel circulation device is a gaseous fuel circulation device for an engine that burns gaseous fuel, and comprises a double pipe having an inner pipe through which the gaseous fuel flows and an outer pipe positioned at a predetermined gap from the outer surface of the inner pipe. The double pipe is provided with a detection unit for detecting the state of the gaseous fuel. The detection unit includes a state detection sensor positioned from inside the inner pipe to outside the outer pipe, and a cover unit that covers a protruding part of the state detection sensor that protrudes from the outer pipe.

Description

Technical Field

[0001] The present invention relates to a gaseous fuel circulation device and an engine.

Background Art

[0002] Patent Document 1 discloses a gas fuel transport pipe for an engine of a ship that uses natural gas as fuel. The gas fuel transport pipe is surrounded in a double tubular shape by a duct as a safety measure against gas leakage from the gas fuel transport pipe.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in order to realize engine control suitable for the combustion of gaseous fuel (gas fuel), it is desirable to directly detect the state of the gaseous fuel with a state detection sensor and perform control based on the detected state of the gaseous fuel. However, for example, in order to detect the state of the gaseous fuel flowing in the inner pipe (gas fuel transport pipe), if the state detection sensor is arranged across from the inside of the inner pipe to the outside of the outer pipe (duct), that is, if a part thereof protrudes from the outer pipe, there is a risk that the gaseous fuel will leak outside the outer pipe.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a technique capable of detecting the state of the gaseous fuel flowing in the inner pipe and preventing the leakage of the gaseous fuel to the outside of the outer pipe.

Means for Solving the Problems

[0006] A gaseous fuel circulation device according to one aspect of the present invention is a gaseous fuel circulation device for an engine that burns a gaseous fuel, comprising a double pipe having an inner pipe through which the gaseous fuel flows and an outer pipe arranged with a predetermined gap between it and the outer surface of the inner pipe, wherein the double pipe is provided with a detection unit for detecting the state of the gaseous fuel, and the detection unit includes a state detection sensor arranged from inside the inner pipe to outside the outer pipe and a cover unit that covers a protruding portion of the state detection sensor that protrudes from the outer pipe.

[0007] An engine according to another aspect of the present invention is equipped with the gaseous fuel circulation device described above. [Effects of the Invention]

[0008] With the above configuration, it is possible to detect the state of the gaseous fuel flowing inside the inner pipe and to prevent the gaseous fuel from leaking outside the outer pipe. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side view showing the schematic configuration of an engine according to one embodiment of the present invention. [Figure 2] This is a plan view showing the general configuration of the engine described above. [Figure 3] This is a schematic diagram illustrating the general configuration of the engine described above. [Figure 4] This is a horizontal cross-sectional view of the detection unit installed in the gaseous fuel flow system of the above-mentioned engine. [Figure 5] This is a rear view showing the configuration of the detection unit described above. [Figure 6] This is a vertical cross-sectional view showing an enlarged view of the area around the state detection sensor provided in the detection unit described above. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings.

[0011] [1. General Engine Configuration] Figures 1 and 2 are a side view and a top view showing the schematic configuration of an engine 1 according to one embodiment of the present invention. Figure 3 is a schematic diagram illustrating the schematic configuration of the engine 1. Note that, for convenience, Figure 2 only shows a part of the engine body 2, the gaseous fuel circulation device 5, and the exhaust manifold 6, which will be described later. Furthermore, the positional relationships of the parts in Figure 3 are merely for explaining the schematic configuration of the engine 1 and are not intended to limit the positional relationships of the parts in this embodiment.

[0012] Engine 1 is mounted on a ship, for example. However, Engine 1 may also be mounted on agricultural machinery such as tractors, construction machinery such as hydraulic excavators, etc. Furthermore, Engine 1 may be installed on land and used for power generation.

[0013] Engine 1 generates a fuel-air mixture by injecting gaseous fuel into air drawn in from the outside, i.e., the intake air. This mixture is then compressed, and liquid fuel is injected into the heated mixture to burn the gaseous fuel (in the mixture), thereby generating power (also called rotational power). More specifically, the gaseous fuel is ignited and burned by the self-ignition of the liquid fuel injected into the high-temperature mixture. In this embodiment, the gaseous fuel is hydrogen, but it is not limited to this; for example, ammonia or natural gas may also be used. Similarly, the liquid fuel is diesel fuel, but it is not limited to this; for example, heavy oil or biofuel may also be used. In other words, Engine 1 in this embodiment is a mixed-fuel engine using gaseous fuel (hydrogen) and liquid fuel (diesel fuel). However, the configuration of Engine 1 is not limited to the above; for example, it may be a dedicated gaseous fuel engine.

[0014] Engine 1 comprises an engine body 2, an intake pipe 3, an intake manifold 4, a gaseous fuel circulation device 5, an exhaust manifold 6, an exhaust pipe 7, and a turbocharger 8. The engine body 2 includes a cylinder block 21, an oil pan 22, a piston 23, a crankshaft 24, a flywheel 25, a cylinder head 26, and a gaseous fuel supply unit 27.

[0015] Here, the directions in this embodiment are defined as follows. In particular, as shown in FIGS. 1 and 2, the direction in which the cylinder block 21 and the oil pan 22 are arranged is defined as the vertical direction. With respect to the cylinder block 21, the direction in which the oil pan 22 is located is defined as "downward", and the opposite direction is defined as "upward". Further, the direction in which the center line 24C of the crankshaft 24 extends (also referred to as the axial direction of the crankshaft 24) is defined as the front-rear direction. With respect to the cylinder block 21, the direction in which the flywheel 25 is located is defined as "front", and the opposite direction is defined as "rear". Furthermore, the direction perpendicular to the vertical direction and the front-rear direction is defined as the left-right direction. With respect to the cylinder block 21, the direction in which the exhaust manifold 6 is located is defined as "right", and the opposite direction is defined as "left". In the drawings, as necessary, the front is indicated by the symbol "F", the rear is indicated by the symbol "B", the left is indicated by the symbol "L", the right is indicated by the symbol "R", the upper is indicated by the symbol "U", and the lower is indicated by the symbol "D". Note that these directions are merely names used for explanation purposes and do not intend to limit the actual positional relationship and direction.

[0016] The cylinder block 21 is composed of a rectangular parallelepiped-shaped metal member extending in the front-rear direction and the vertical direction, and its longitudinal direction extends in the front-rear direction. The lower part of the cylinder block 21 is connected to an oil pan 22 that stores lubricating oil used for lubricating each part of the engine body 2.

[0017] In the cylinder block 21, cylindrical cylinders 211 extending in the vertical direction are formed. The cylinders 211 extend downward from the upper surface portion of the cylinder block 21, and six of them are arranged side by side in the front-rear direction. That is, the engine 1 includes a plurality (six in this embodiment) of cylinders 211. Note that the number of cylinders 211 is not limited to six, and it may be one, or a plurality other than six.

[0018] In each cylinder 211, a piston 23 is accommodated so as to be slidable (i.e., reciprocally movable) in the vertical direction (inside the cylinder 211). Each piston 23 is composed of a cylindrical metal member. Each piston 23 is connected to the crankshaft 24 via a connecting rod (not shown).

[0019] The crankshaft 24 is supported rotatably with respect to the cylinder block 21 at the lower part of the cylinder block 21. The crankshaft 24 converts the reciprocating motion of each piston 23 into a rotational motion. The front end of the crankshaft 24 is connected via a flywheel 25 to a propulsion device (not shown) mounted on the ship. The flywheel 25 is provided for absorbing the rotational fluctuations of the engine 1 and preventing torsional vibrations and the like. The above-described propulsion device is configured to be able to attach a propeller (not shown) and generates the propulsion force of the ship.

[0020] The cylinder head 26 is composed of a substantially rectangular parallelepiped-shaped metal member and is connected to the upper part of the cylinder block 21. The cylinder head 26 is provided corresponding to each cylinder 211 of the cylinder block 21. That is, in the present embodiment, the number of cylinder heads 26 is six. Each cylinder head 26 is disposed above the cylinder 211. In the present embodiment, in each cylinder 211, the space surrounded by the inner peripheral surface of the cylinder 211, the top surface of the piston 23, and the bottom surface of the cylinder head 26 is also called a combustion chamber.

[0021] In each cylinder head 26, an intake port (not shown) for supplying intake air to the combustion chamber and an exhaust port (not shown) for discharging exhaust gas from the combustion chamber are formed. Further, an injector 261 is attached to each cylinder head 26. That is, in the present embodiment, the number of injectors 261 is six. Each injector 261 injects the liquid fuel stored at high pressure in the common rail 261a into the corresponding combustion chamber at a predetermined timing. The pumping of the liquid fuel to the common rail 261a is performed by a supply pump 261b. The supply pump 261b is driven by the power of the engine 1 transmitted from the crankshaft 24 via a belt member (not shown) or the like.

[0022] The gaseous fuel supply units 27 are provided in accordance with each cylinder 211, similar to the cylinder head 26. In other words, in this embodiment, there are six gaseous fuel supply units 27. Each gaseous fuel supply unit 27 is located near the cylinder head 26 (for example, to the right of the cylinder head 26) that corresponds to the cylinder 211. Each gaseous fuel supply unit 27 is fitted with a supply valve 271 capable of supplying (injecting) gaseous fuel to the intake air supplied to the combustion chamber. In other words, the engine 1 is equipped with a plurality of supply valves 271 that supply gaseous fuel to each cylinder 211.

[0023] The force generated by the combustion of gaseous fuel supplied to each combustion chamber causes each piston 23 to reciprocate within the cylinder 211. This causes the crankshaft 24 to rotate, enabling power to be extracted from the engine 1 to the outside.

[0024] The intake pipe 3 draws in air from the outside and supplies it to the intake manifold 4. The intake manifold 4 supplies the air (intake) supplied from the intake pipe 3 to each combustion chamber (each cylinder 211) via the intake port of each cylinder head 26.

[0025] The gaseous fuel distribution device 5 distributes gaseous fuel to each supply valve 271. More specifically, the gaseous fuel distribution device 5 includes a double pipe 51. The double pipe 51 has an inner pipe 51a and an outer pipe 51b. The inner pipe 51a and the outer pipe 51b are each made of tubular metal members. The inner pipe 51a is located radially inward of the double pipe 51 relative to the outer pipe 51b. Radially inward of the double pipe 51 means the direction approaching the central axis of the double pipe 51 in a direction perpendicular to the central axis of the double pipe 51 (also called the radial direction of the double pipe 51). Radially outward of the double pipe 51 means the direction away from the central axis of the double pipe 51 in the radial direction of the double pipe 51.

[0026] The gaseous fuel flows through the inner pipe 51a toward each supply valve 271. In other words, the inner pipe 51a is the pipe through which the gaseous fuel flows. Details of the configuration of the inner pipe 51a and the outer pipe 51b will be described later.

[0027] The double-walled pipe 51 is provided with a connecting pipe section 511, a distribution section 512, a detection section 513, and a ventilation flow path switching section 514. The connecting pipe section 511 includes a connecting pipe 511a. One end of the connecting pipe 511a is connected to a gaseous fuel tank 53 for storing gaseous fuel via a valve unit 52. The valve unit 52 includes various control valves. These control valves include an on / off valve that can switch the communication between the connecting pipe 511a and the gaseous fuel tank 53 on and off, a bleed valve used when discharging gaseous fuel from at least one of the double-walled pipe 51 and the gaseous fuel tank 53, and the like. The other end of the connecting pipe 511a is connected to the distribution section 512.

[0028] The distribution section 512 includes an inlet pipe 512a, a common pipe 512b, and a plurality of branch pipes 512c. The inlet pipe 512a extends in the left-right direction. The right end of the inlet pipe 512a is connected to the connecting pipe 511a, and the left end is connected to the common pipe 512b.

[0029] The common pipe 512b extends in the front-rear direction (the axial direction of the crankshaft 24). That is, the common pipe 512b is arranged to extend in one direction (the front-rear direction in this embodiment). Note that the direction in which the common pipe 512b extends is not limited to the front-rear direction, but may be, for example, the left-right direction or the up-down direction. Furthermore, the direction in which the common pipe 512b extends may be an oblique direction that is inclined with respect to at least one of the front-rear direction, the left-right direction, or the up-down direction.

[0030] The common pipe 512b is positioned above the exhaust manifold 6. More specifically, the exhaust manifold 6 is located to the right of the cylinder block 21, extending in the front-to-back and left-to-right directions. In a plan view (looking at the engine 1 from above), the common pipe 512b is positioned to the left of the left-to-right center of the exhaust manifold 6. The exhaust manifold 6 collects the exhaust gases discharged from each combustion chamber through the exhaust ports of the cylinder head 26 and discharges them into the exhaust pipe 7.

[0031] The exhaust pipe 7 discharges the exhaust gas collected in the exhaust manifold 6 to the outside of the ship. A turbine 81 is installed in the exhaust pipe 7. The turbine 81 is connected to a compressor 83 via a connecting shaft 82. The compressor 83 is installed in the intake pipe 3. The turbine 81, connecting shaft 82, and compressor 83 constitute a turbocharger 8. The turbine 81 rotates when struck by the exhaust gas flowing through the exhaust pipe 7. The compressor 83 is driven by the rotational power of the turbine 81 transmitted via the connecting shaft 82 and compresses the intake air. Therefore, the turbocharger 8 makes it possible to increase the amount of intake air supplied to each combustion chamber (each cylinder 211). Note that the engine 1 may be configured without the turbocharger 8. Alternatively, the engine 1 may be configured with a supercharging mechanism other than the turbocharger 8.

[0032] Multiple branch pipes 512c are connected to the lower part of the common pipe 512b. The branch pipes 512c are provided corresponding to each gaseous fuel supply unit 27 of the engine body 2. In other words, in this embodiment, there are six branch pipes 512c. Each branch pipe 512c extends in the vertical direction. The upper end of each branch pipe 512c is connected to the common pipe 512b, and the lower end is connected to the gaseous fuel supply unit 27. The multiple branch pipes 512c communicate with the common pipe 512b and each supply valve 271. In other words, the common pipe 512b communicates with each supply valve 271.

[0033] Therefore, the gaseous fuel stored in the gaseous fuel tank 53 flows into each branch pipe 512c via the valve unit 52, connecting pipe 511a, and common pipe 512b. The gaseous fuel that flows into each branch pipe 512c is supplied to the combustion chamber by the supply valve 271 of the gaseous fuel supply unit 27 corresponding to each branch pipe 512c. In other words, the distribution unit 512 distributes the gaseous fuel to each supply valve 271.

[0034] A first flange F1 is provided at the rear end 512b1 of the common pipe 512b. A second flange F2, corresponding to the first flange F1, is provided at the front end of the detection unit 513. A third flange F3, used for connection with the ventilation flow path switching unit 514, is provided at the rear end of the detection unit 513.

[0035] The first flange F1, the second flange F2, and the third flange F3 are each composed of disc-shaped metal members extending vertically (up and down and left and right) in the direction perpendicular to the horizontal direction. However, the shape of the first flange F1, the second flange F2, and the third flange F3 is not limited to a circle, and may be, for example, an ellipse, a square, a rectangle, or a polygon other than a square and a rectangle.

[0036] The first flange F1 and the second flange F2 are fixed together by fastening members such as bolts, thereby connecting the common pipe 512b and the detection unit 513. That is, the detection unit 513 is connected to the end 512b1 on one side (the rear side in this embodiment) of the common pipe 512b. The rear end 512b1 of the common pipe 512b constitutes one end 512E1 of the distribution unit 512. In other words, the detection unit 513 is connected to one end 512E1 of the distribution unit 512. The front end of the common pipe 512b constitutes the other end 512E2 of the distribution unit 512.

[0037] For example, let's compare the case where the detection unit 513 is attached to one end 512E1 of the distribution unit 512 with the case where the detection unit 513 is attached to an intermediate section (not shown) between one end 512E1 and the other end 512E2 of the distribution unit 512. Attaching the detection unit 513 to the intermediate section requires processing of the intermediate section, but attaching the detection unit 513 to the one end 512E1 does not require processing of the one end 512E1. Therefore, attaching the detection unit 513 to the one end 512E1 is less labor-intensive. The processing includes, for example, cutting and attaching connecting members (not shown). Furthermore, the less labor-intensive (easier) method of attaching the detection unit 513 is particularly suitable for configurations where the detection unit 513 is added later. Therefore, in a double pipe 51, a distribution unit 512 is provided to distribute gaseous fuel to a plurality of supply valves 271 that supply gaseous fuel to a plurality of cylinders 211 of the engine 1. From the viewpoint of easily installing (adding later) the detection unit 513, the following configuration is desirable. That is, as in this embodiment, it is desirable that the detection unit 513 be connected to one end 512E1 of the distribution unit 512.

[0038] In a configuration in which the distribution unit 512 includes a common pipe 512b that communicates with each supply valve 271, and the common pipe 512b is arranged to extend in one direction (the front-to-back direction in this embodiment), the following configuration is desirable in order to reliably realize a configuration that facilitates the installation (retrofitting) of the detection unit 513. That is, as in this embodiment, it is desirable that the detection unit 513 be connected to the end 512b1 on one side (the rear side in this embodiment) of the common pipe 512b in one direction.

[0039] Furthermore, by removing the fixing member that secures the first flange F1 and the second flange F2, the connection between the common pipe 512b and the detection unit 513 is released. In other words, the detection unit 513 is detachably provided on the double pipe 51.

[0040] From the viewpoint of realizing a configuration suitable for retrofitting the detection unit 513 or for maintenance of the detection unit 513 (e.g., inspection, replacement, etc.), it is desirable that the detection unit 513 be detachably provided on the double pipe 51, as in this embodiment.

[0041] The ventilation flow path switching unit 514 has its front end connected to the detection unit 513 (specifically, the rear end of the detection unit 513), and its rear end connected to a blower (not shown) mounted on the ship. The blower sends outside air from the ship into the double pipe 51 via the ventilation flow path switching unit 514. The blower is, for example, a blower, a fan, etc. The ventilation flow path switching unit 514 also includes a switching valve 514a that can switch on and off the communication between the airflow path (not shown) through which the air sent from the blower flows and the inside of the inner pipe 51a. The function of the switching valve 514a will be described later.

[0042] Engine 1 is also equipped with a control device (not shown) for controlling Engine 1. The control device can be mounted on the ship and may be located near the engine body 2, or it may be located away from the engine body 2. The configuration of the detection unit 513 will be described below.

[0043] [2. Configuration of the detection unit] Figure 4 is a horizontal cross-sectional view of the detection unit 513, cut horizontally at the position through which the line A-A' in Figure 1 passes. In the detection unit 513, the inner tube 51a and the outer tube 51b are connected via a second flange F2 located at the front end of the detection unit 513 and a third flange F3 located at the rear end of the detection unit 513. As described above, the inner tube 51a is located radially inward of the double tube 51 relative to the outer tube 51b. More specifically, a predetermined gap 51c is formed between the outer circumferential surface 51a1 of the inner tube 51a and the inner circumferential surface 51b1 of the outer tube 51b. In other words, the outer tube 51b is positioned with a predetermined gap 51c between it and the outer circumferential surface 51a1 of the inner tube 51a.

[0044] The predetermined gap 51c communicates with the blower and the outside of the ship via the communication passages FP formed in the second flange F2 and the third flange F3, respectively. More specifically, the predetermined gap 51c communicates with the blower via the communication passage FP of the third flange F3, the ventilation flow path switching section 514 (see Figure 1, etc.), etc. The predetermined gap 51c also communicates with the outside of the ship via the communication passage FP of the second flange F2, the space between the inner pipe 51a and the outer pipe 51b in the common pipe 512b (see Figure 1, etc.), the space between the inner pipe 51a and the outer pipe 51b in the connecting pipe 511a (see Figure 1, etc.), etc. Each communication passage FP is formed extending in the front-rear direction.

[0045] When the blower is driven, outside air from the ship is sent to a predetermined gap 51c via the ventilation flow path switching section 514 and the connecting passage FP of the third flange F3. The air that flows into the predetermined gap 51c flows from rear to front. The air that has flowed through the predetermined gap 51c is released to the outside of the ship via the connecting passage FP of the second flange F2, the space between the inner pipe 51a and the outer pipe 51b in the common pipe 512b, and the space between the inner pipe 51a and the outer pipe 51b in the connecting pipe 511a. Therefore, for example, even if a part of the joint between the inner pipe 51a and the second flange F2 opens and gaseous fuel flowing inside the inner pipe 51a leaks out from this opening, the leaked gaseous fuel is released to the outside of the ship safely by the air flowing through the predetermined gap 51c. In other words, the air flowing through the predetermined gap 51c is used for ventilation of the predetermined gap 51c. Furthermore, ventilation of the predetermined gap 51c is performed at all times, at least while gaseous fuel is being used in engine 1 (while gaseous fuel is being circulated in the gaseous fuel circulation device 5).

[0046] When the switching valve 514a (see Figure 1, etc.) of the ventilation flow path switching unit 514 is driven, and the flow path within the ventilation flow path switching unit 514 communicates with the inside of the inner pipe 51a (of the ventilation flow path switching unit 514), a portion of the air supplied from the blower flows into the inner pipe 51a. This enables ventilation of the inner pipe 51a (also called purging of the inner pipe 51a). Ventilation of the inner pipe 51a is performed at appropriate timings. The timing for ventilating the inner pipe 51a (i.e., driving the switching valve 514a) is determined by the control device described above.

[0047] The detection unit 513 includes a mounting portion 513a, a state detection sensor 513b, and a cover portion 513c. More details are as follows. Figure 5 is a rear view showing the configuration of the detection unit 513. Note that, for convenience, the third flange F3 is omitted from the illustration in Figure 5.

[0048] The mounting portions 513a are positioned on the lower left, lower right, and upper sides of the inner pipe 51a. In other words, in this embodiment, there are three mounting portions 513a. More specifically, the three mounting portions 513a are positioned offset from each other in the front-rear direction while being offset in the circumferential direction of the double pipe 51 (see also Figure 4). Specifically, one of the three mounting portions 513a (the lower left mounting portion 513a in Figure 5) extends in a first inclination direction, with the upper side inclined to the right with respect to the vertical direction. One of the remaining two (the lower right mounting portion 513a in Figure 5) is positioned slightly forward of the mounting portion 513a extending in the first inclination direction (see Figure 4), and extends in a second inclination direction, with the upper side inclined to the left with respect to the vertical direction. The other of the remaining two (the upper mounting portion 513a in Figure 5) is positioned extending vertically between the mounting portion 513a extending in the first inclination direction and the mounting portion 513a extending in the second inclination direction, in the front-to-back direction.

[0049] The number of mounting parts 513a is not limited to three; for example, there may be one or more than three. Furthermore, the arrangement of the mounting parts 513a is not limited to the above. For example, the three mounting parts 513a may be arranged side-by-side in the circumferential direction of the double pipe 51, or they may be arranged side-by-side in the front-to-back direction.

[0050] State detection sensors 513b are attached to two of the three mounting parts 513a (the lower left and lower right mounting parts 513a in Figure 5). The remaining one (the upper mounting part 513a in Figure 5) is excluded from the mounting of the state detection sensor 513b as a spare. Therefore, in this embodiment, there are two state detection sensors 513b. However, the above configuration is not limited, and for example, state detection sensors 513b may be attached to one or all of the three mounting parts 513a. That is, state detection sensors 513b may be attached to at least one of the three mounting parts 513a. In other words, the number of state detection sensors 513b may be one or more than two. A cover part 513c, etc., which will be described later, is also provided for the (spare) mounting part 513a that is excluded from the mounting of the state detection sensor 513b.

[0051] Each mounting portion 513a includes a mounting member 513a1 made of a cylindrical metal member. However, the configuration of the mounting member 513a1 is not limited to the above, and may be, for example, rectangular. Each mounting member 513a1 is joined to the outer circumferential surface 51a1 of the inner pipe 51a by welding or the like. That is, each mounting portion 513a is connected to the outer circumferential surface 51a1 of the inner pipe 51a.

[0052] One state detection sensor 513b (the left state detection sensor 513b in Figure 5) is a pressure sensor that detects the pressure of the gaseous fuel flowing through the inner pipe 51a. The other state detection sensor 513b (the right state detection sensor 513b in Figure 5) is a temperature sensor that detects the temperature of the gaseous fuel flowing through the inner pipe 51a. The pressure and temperature of the gaseous fuel are included in the state of the gaseous fuel. In other words, the detection unit 513 detects the state of the gaseous fuel (pressure and temperature in this embodiment) using each state detection sensor 513b.

[0053] The configuration of the two state detection sensors 513b is not limited to the above. For example, both of the two state detection sensors 513b may be pressure sensors, or both of the two state detection sensors 513b may be temperature sensors. Also, at least one of the two state detection sensors 513b may be a sensor other than a pressure sensor and a temperature sensor (e.g., a flow sensor). In other words, the state of the gaseous fuel may include, for example, the flow rate.

[0054] One state detection sensor 513b is attached to a mounting member 513a1 included in a mounting portion 513a that extends in the first inclination direction (a direction in which the upper side is inclined to the right with respect to the vertical direction). The other state detection sensor 513b is attached to a mounting member 513a1 included in a mounting portion 513a that extends in the second inclination direction (a direction in which the upper side is inclined to the left with respect to the vertical direction). In other words, the state detection sensors 513b are attached to the mounting portion 513a. That is, the state detection sensors 513b are attached to the inner pipe 51a via the mounting portion 513a. More details are as follows. Figure 6 is a vertical cross-sectional view showing an enlarged view of the area around one state detection sensor 513b, obtained by cutting the detection portion 513 vertically at the position through which the line B-B' in Figure 4 passes. In the following, as an example, the mounting configuration (and gaseous fuel leakage prevention structure) of the state detection sensor 513b will be described based on one state detection sensor 513b.

[0055] At least a portion of the inner circumferential surface of the mounting member 513a1 has a female thread, and at least a portion of the outer circumferential surface of the state detection sensor 513b has a male thread. The inner tube 51a is provided with a first outlet 51a2 that penetrates the double tube 51 in the radial direction (first inclination direction in Figure 6) (see also Figure 4). Furthermore, the outer tube 51b is provided with a second outlet 51b2 that penetrates the double tube 51 in the radial direction (first inclination direction in Figure 6) (see also Figure 4). That is, the inner tube 51a includes the first outlet 51a2 that opens radially outward of the double tube 51, and the outer tube 51b includes the second outlet 51b2 that opens radially outward of the double tube 51. In particular, the second outlet 51b2 is provided at a position that overlaps with the first outlet 51a2 when viewed from the radially outward side of the double tube 51.

[0056] When attaching the state detection sensor 513b to the mounting member 513a1, the state detection sensor 513b is inserted from the radially outer side of the double pipe 51 (lower left in Figure 6) into the first outlet 51a2 of the inner pipe 51a and the inner circumferential surface of the mounting member 513a1, and then screwed into the mounting member 513a1. The above screwing means that a member having a male thread (state detection sensor 513b in this embodiment) and a member having a female thread (mounting member 513a1 in this embodiment) are interlocked and joined. As a result, the state detection sensor 513b is attached (fixed) to the mounting member 513a1 while passing through the first outlet 51a2.

[0057] The mounting member 513a1 is connected to the outer surface 51a1 of the inner pipe 51a while passing through the second outlet 51b2 of the outer pipe 51b. Therefore, the state detection sensor 513b is positioned through the first outlet 51a2 and the second outlet 51b2. In other words, the state detection sensor 513b is positioned from inside the inner pipe 51a to outside the outer pipe 51b. Specifically, the tip portion 513b1 of the state detection sensor 513b is located inside the inner pipe 51a, and the base portion 513b2 of the state detection sensor 513b is located outside the outer pipe 51b.

[0058] An adapter 513a2 is provided between the state detection sensor 513b and the mounting member 513a1. The adapter 513a2 is provided to match the outer diameter of the threaded portion of the state detection sensor 513b with the inner diameter of the mounting member 513a1. However, the adapter 513a2 may be removed from the mounting portion 513a.

[0059] In this embodiment, the portion of the state detection sensor 513b that protrudes from the outer tube 51b is also referred to as the protruding portion 513b3. A cover portion 513c is located around the protruding portion 513b3. The cover portion 513c includes a cover member 513c1.

[0060] The cover member 513c1 is composed of a cylindrical metal member extending radially (in the first inclination direction in Figure 6) of the double pipe 51. More specifically, the cover member 513c1 is formed by closing the radially outer side (lower left side in Figure 6) of the double pipe 51. In this embodiment, the internal space of the cover member 513c1 is also referred to as the interior 513c2 of the cover portion 513c. Therefore, an opening 513c3 is provided on the radially inner side (upper right side in Figure 6) of the double pipe 51 in the cover member 513c1, communicating with the interior 513c2 of the cover portion 513c. In addition, a male thread is formed on the radially inner outer surface of the double pipe 51 in the cover member 513c1.

[0061] The cover member 513c1 is provided with a through-hole TH for passing electrical wiring EW through. In this embodiment, the through-hole TH is formed on the radially outer side of the double pipe 51 in the cover member 513c1, penetrating through the double pipe 51 in the radial direction. However, the configuration of the through-hole TH is not limited to the above. For example, the through-hole TH may be formed penetrating in a direction perpendicular to the central axis of the cover member 513c1.

[0062] The electrical wiring EW is connected to the state detection sensor 513b and the control device described above. Information regarding the state of the gaseous fuel detected by the state detection sensor 513b is transmitted to the control device via the electrical wiring EW. The control device controls the engine 1 based on the transmitted information. The through hole TH is provided with a sealing member SP that fills the gap between the outer surface of the electrical wiring EW passing through the through hole TH and the through hole TH.

[0063] The cover member 513c1 is detachably attached to the outer tube 51b via a fastening member 513d. The fastening member 513d is a cylindrical metal member extending in the radial direction (first inclination direction in Figure 6) of the double tube 51. However, the configuration of the fastening member 513d is not limited to the above, and may be, for example, rectangular.

[0064] The radially inner side of the double tube 51 in the fastening member 513d (upper right side in Figure 6) is connected to the outer circumferential surface of the outer tube 51b, specifically around the second outlet 51b2. Therefore, when viewed from the radially outer side of the double tube 51, the second outlet 51b2 is located radially inward of the fastening member 513d relative to its inner circumferential edge. Radially inward of the fastening member 513d means the direction approaching the central axis of the fastening member 513d in a direction perpendicular to the central axis of the fastening member 513d. Furthermore, an internal thread is formed on the inner circumferential surface of the fastening member 513d.

[0065] When attaching the cover member 513c1 to the outer pipe 51b via the fastening member 513d, the cover member 513c1, which is located radially outward of the double pipe 51, is moved radially inward relative to the fastening member 513d. At this time, the opening 513c3 of the cover member 513c1 is moved while corresponding to (aligning) the protruding portion 513b3 and the mounting member 513a1. Then, the cover member 513c1 is inserted into the inner periphery of the fastening member 513d and screwed into the fastening member 513d. As a result, the cover member 513c1 can be attached to the outer pipe 51b via the fastening member 513d while covering the protruding portion 513b3 and the radially outward side of the double pipe 51 at the mounting member 513a1. In other words, the cover portion 513c covers the protruding portion 513b3 of the state detection sensor 513b that protrudes from the outer pipe 51b.

[0066] With the above configuration, a portion of the state detection sensor 513b, which can detect the state of the gaseous fuel (pressure and temperature in this embodiment), can be placed within the flow of the gaseous fuel inside the inner pipe 51a. Alternatively, another portion of the state detection sensor 513b can be placed outside the outer pipe 51b. Therefore, even in a double-walled pipe 51 having an inner pipe 51a and an outer pipe 51b separated from the inner pipe 51a by a predetermined gap 51c, the detection unit 513 can be provided in a configuration that allows for direct detection and output of the state of the gaseous fuel flowing inside the inner pipe 51a. This enables control of the engine 1 based on the directly detected state of the gaseous fuel, thereby achieving engine control optimized for the combustion of the gaseous fuel.

[0067] Furthermore, for example, let's assume that the gaseous fuel flowing inside the inner pipe 51a flows out through the space between the state detection sensor 513b and the inner pipe 51a, and between the state detection sensor 513b and the outer pipe 51b, towards the protruding portion 513b3 of the state detection sensor 513b located outside the outer pipe 51b. In this assumption, since the protruding portion 513b3 is covered by the cover portion 513c, the flowing gaseous fuel can be contained within the cover portion 513c. Therefore, leakage of gaseous fuel outside the outer pipe 51b can be prevented. As a result, the state of the gaseous fuel flowing inside the inner pipe 51a can be detected, and leakage of gaseous fuel outside the outer pipe 51b can be prevented.

[0068] In a configuration where the inner pipe 51a includes a first outlet 51a2 and the outer pipe 51b includes a second outlet 51b2, and these open radially outward from the double pipe 51, the following configuration is desirable in terms of reliably realizing the placement of the state detection sensor 513b from inside the inner pipe 51a to outside the outer pipe 51b. That is, as in this embodiment, it is desirable that the state detection sensor 513b be placed through the first outlet 51a2 and the second outlet 51b2.

[0069] When the cover member 513c1 is attached to the outer pipe 51b (via the fastening member 513d), the opening 513c3 of the cover member 513c1 is connected to the second outlet 51b2 of the outer pipe 51b. As described above, the second outlet 51b2 penetrates the double pipe 51 radially. Therefore, the second outlet 51b2 communicates with a predetermined gap 51c (located between the inner pipe 51a and the outer pipe 51b). Thus, the opening 513c3 and the second outlet 51b2 connect the interior 513c2 of the cover portion 513c (the interior space of the cover member 513c1 in this embodiment) to the predetermined gap 51c. In other words, the interior 513c2 of the cover portion 513c communicates with the predetermined gap 51c.

[0070] More specifically, the cover member 513c1 is attached to the outer pipe 51b by moving the opening 513c3 in correspondence with the mounting member 513a1, as described above. Therefore, the mounting member 513a1 is positioned passing through the opening 513c3. Also, as described above, the mounting member 513a1 is positioned passing through the second outlet 51b2. In this embodiment, the space other than the space through which the mounting member 513a1 passes (the gap between the opening 513c3 and the second outlet 51b2 and the outer circumferential surface of the mounting member 513a1) is also called the communication portion 513e. Therefore, the detection unit 513 includes the communication portion 513e, which connects the interior 513c2 of the cover member 513c with a predetermined gap 51c and is located around the mounting portion 513a.

[0071] It is desirable to release the gaseous fuel contained in the cover portion 513c into a predetermined gap 51c, and to release it to the outside (outside the ship in this embodiment) while ensuring safety, using the air flowing through the predetermined gap 51c. From this viewpoint, it is desirable that the inside 513c2 of the cover portion 513c communicates with the predetermined gap 51c, as in this embodiment.

[0072] In this configuration, the detection unit 513 includes a mounting portion 513a to which the state detection sensor 513b is attached. From the viewpoint of attaching the state detection sensor 513b to the inner pipe 51a, it is desirable that the mounting portion 513a is connected to the outer surface 51a1 of the inner pipe 51a, as in this embodiment. Furthermore, even if the detection unit 513 includes a mounting portion 513a, it is desirable to reliably realize a configuration in which the inside 513c2 of the cover portion 513c and a predetermined gap 51c are in communication. From this viewpoint, it is desirable that, as in this embodiment, the detection unit 513 includes a communication portion 513e in addition to the mounting portion 513a, which connects the inside 513c2 of the cover portion 513c and the predetermined gap 51c, and that the communication portion 513e is arranged around the mounting portion 513a.

[0073] With respect to the communication portion 513e, the protruding portion 513b3 of the state detection sensor 513b is located radially outward of the double pipe 51, and the predetermined gap 51c is located radially inward of the double pipe 51. That is, the predetermined gap 51c, the protruding portion 513b3, and the communication portion 513e are arranged in the order of protruding portion 513b3, communication portion 513e, and predetermined gap 51c, from the radially outward to the radially inward of the double pipe 51.

[0074] For example, in the case of a gaseous fuel with a lower specific gravity (lighter) than air, as in this embodiment, if the protrusion 513b3, the connecting portion 513e, and the predetermined gap 51c are positioned in that order from bottom to top, the gaseous fuel remaining in the cover portion 513c will flow more easily into the predetermined gap 51c. On the other hand, in the case of a gaseous fuel with a higher specific gravity (heavier) than air, if the protrusion 513b3, the connecting portion 513e, and the predetermined gap 51c are positioned in that order from top to bottom, the gaseous fuel remaining in the cover portion 513c will flow more easily into the predetermined gap 51c. Therefore, from the viewpoint of realizing a configuration in which the gaseous fuel remaining in the cover portion 513c flows easily towards the predetermined gap 51c, according to the specific gravity of the gaseous fuel, the following configuration is desirable. In other words, as in this embodiment, it is desirable that the predetermined gap 51c, the protruding portion 513b3, and the connecting portion 513e be arranged in the order of the protruding portion 513b3, the connecting portion 513e, and the predetermined gap 51c, from the radially outer side to the radially inner side of the double pipe 51.

[0075] [3. Supplement] In this embodiment, for convenience, the explanation of the mounting configuration of the other state detection sensor 513b and the gaseous fuel leakage prevention structure has been omitted. However, the mounting configuration of the other state detection sensor 513b is substantially the same as that of the first state detection sensor 513b. Specifically, the mounting configuration of the other state detection sensor 513b is the same as that of the first state detection sensor 513b, except that the mounting direction (arrangement direction) of the state detection sensor 513b is different and the adapter 513a2 is removed. Furthermore, the gaseous fuel leakage prevention structure in the other state detection sensor 513b is the same as that in the first state detection sensor 513b.

[0076] In this embodiment, the case where the rear is defined as "one side in one direction" and the front is defined as "the other side in one direction" has been described, but the embodiment is not limited to this. For example, the front may be defined as "one side in one direction" and the rear as "the other side in one direction." In other words, the front and rear may be reversed.

[0077] [4. Addendum] The gaseous fuel circulation device 5 and engine 1 described in this embodiment can also be expressed as the gaseous fuel circulation device and engine shown in the following appendix.

[0078] The gaseous fuel distribution system in Appendix (1) is A gaseous fuel circulation system for an engine that burns gaseous fuel, An inner pipe through which the aforementioned gaseous fuel flows, The double-walled pipe comprises an outer pipe positioned at a predetermined gap from the outer surface of the inner pipe, The double-walled pipe is provided with a detection unit for detecting the state of the gaseous fuel. The detection unit is A state detection sensor is positioned extending from inside the inner pipe to outside the outer pipe, The state detection sensor includes a cover portion that covers a protruding portion that protrudes from the outer tube.

[0079] The gaseous fuel distribution system in Appendix (2) is the same as the gaseous fuel distribution system described in Appendix (1), The inner tube includes a first outlet that opens radially outward from the double tube, The outer tube includes a second outlet that opens radially outward from the double tube, The state detection sensor is positioned through the first outlet and the second outlet.

[0080] The gaseous fuel distribution system in Appendix (3) is the gaseous fuel distribution system described in Appendix (1) or (2), The inside of the cover portion is in communication with the predetermined gap.

[0081] The gaseous fuel distribution system in Appendix (4) is the same as the gaseous fuel distribution system described in Appendix (3), The detection unit is A mounting portion to which the state detection sensor is attached, It includes a communication portion that connects the interior and the predetermined gap, The mounting portion is connected to the outer circumferential surface, The aforementioned communication portion is located around the aforementioned mounting portion.

[0082] The gaseous fuel distribution system in Appendix (5) is the same as the gaseous fuel distribution system described in Appendix (4), The protruding portion, the connecting portion, and the predetermined gap are arranged in the order of radially outward to radially inward of the double pipe.

[0083] The gaseous fuel distribution system in Appendix (6) is a gaseous fuel distribution system described in any of Appendix (1) to (5), The detection unit is detachably mounted on the double tube.

[0084] The gaseous fuel distribution system in Appendix (7) is a gaseous fuel distribution system described in any of Appendix (1) to (6), The aforementioned engine is Multiple cylinders, The system comprises a plurality of supply valves that supply the gaseous fuel to each of the cylinders, The double pipe is provided with a distribution section for distributing the gaseous fuel to each of the supply valves. The detection unit is connected to one end of the distribution unit.

[0085] The gaseous fuel distribution system in Appendix (8) is the gaseous fuel distribution system described in Appendix (7), The distribution section includes a common pipe that communicates with each of the supply valves, The aforementioned common pipe is arranged to extend in one direction, The detection unit is connected to one end of the common pipe in the aforementioned one direction.

[0086] The engine in Appendix (9) is equipped with a gaseous fuel circulation device as described in any of Appendix (1) to (8).

[0087] Although embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and it can be expanded or modified without departing from the spirit of the invention. [Industrial applicability]

[0088] The present invention can be used, for example, in engines used in ships, working machinery (construction machinery, agricultural machinery, etc.), and power generation equipment. [Explanation of symbols]

[0089] 1 Engine 5. Gas Fuel Distribution System 51 Double pipe 51a Inner tube 51a1 Outer surface (outer surface of the inner tube) 51a2 1st outlet 51b Outer tube 51b2 2nd outlet 51c Predetermined gap 211 Cylinder 512 Distribution section 512b common pipe 512b1 End (end of common pipe) 513 Detection unit 271 Supply valve 513a Mounting part 513b State detection sensor 513b3 Protrusion 513c Cover 513c2 Interior (Inside the cover) 513e Communication part 512E1 One end (one end of the distribution section)

Claims

1. A gaseous fuel circulation system for an engine that burns gaseous fuel, An inner pipe through which the aforementioned gaseous fuel flows, The double-walled pipe comprises an outer pipe positioned at a predetermined gap from the outer surface of the inner pipe, The double-walled pipe is provided with a detection unit for detecting the state of the gaseous fuel. The detection unit, A state detection sensor is positioned extending from inside the inner pipe to outside the outer pipe, A gaseous fuel flow device, including a cover portion that covers a protruding portion of the state detection sensor that protrudes from the outer tube.

2. The inner tube includes a first outlet that opens radially outward from the double tube, The outer tube includes a second outlet that opens radially outward from the double tube, The gaseous fuel flow device according to claim 1, wherein the state detection sensor is arranged through the first outlet and the second outlet.

3. The gaseous fuel circulation device according to claim 1, wherein the inside of the cover portion is in communication with the predetermined gap.

4. The detection unit, A mounting portion to which the state detection sensor is attached, It includes a communication portion that connects the interior and the predetermined gap, The mounting portion is connected to the outer circumferential surface, The gaseous fuel circulation device according to claim 3, wherein the communication portion is located around the mounting portion.

5. The gaseous fuel circulation device according to claim 4, wherein the protruding portion, the connecting portion, and the predetermined gap are arranged in the order from the radially outer side to the radially inner side of the double pipe.

6. The gaseous fuel circulation device according to claim 1, wherein the detection unit is detachably provided on the double pipe.

7. The aforementioned engine is Multiple cylinders, The system comprises a plurality of supply valves that supply the gaseous fuel to each of the cylinders, The double pipe is provided with a distribution section for distributing the gaseous fuel to each of the supply valves. The gaseous fuel distribution device according to claim 1, wherein the detection unit is connected to one end of the distribution unit.

8. The distribution section includes a common pipe that communicates with each of the supply valves, The aforementioned common pipe is arranged to extend in one direction, The gaseous fuel flow device according to claim 7, wherein the detection unit is connected to one end of the common pipe in the one direction.

9. An engine comprising a gaseous fuel circulation device according to any one of claims 1 to 8.

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