Fuel injection device and reciprocating internal combustion engine

Abstract

To allow a fuel injection amount to be increase / decrease as needed, in a fuel injection device and a reciprocating internal combustion engine.SOLUTION: A fuel injection device comprises: a fuel injection valve having a first needle valve and a second needle valve; a first fuel supply path that supplies fuel to the first needle valve; a second fuel supply path that supplies fuel to the second needle valve; and an on-off valve provided in at least one of the first fuel supply path and the second fuel supply path.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a fuel injection system and a reciprocating internal combustion engine. [Background technology]

[0002] A reciprocating internal combustion engine is equipped with a fuel injection device. The reciprocating internal combustion engine is driven by the combustion energy generated by injecting fuel into high-pressure air in a combustion chamber using the fuel injection device. The fuel injection device adjusts the amount of fuel injected depending on the required load. In recent years, the use of carbon-free fuels, which generate fewer harmful substances (such as carbon dioxide), has been considered. However, some carbon-free fuels have poor ignition and combustion properties, and therefore need to be used in combination with fuels with good ignition and combustion properties. In this case, the fuel injection device injects the carbon-free fuel as the main fuel and injects fuel with good ignition properties as the pilot fuel. An example of such a fuel injection device is described in Patent Document 1 below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-180567 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional fuel injection devices are required to increase the injection amount according to the required load, while also being able to decrease the fuel injection amount as needed. In this case, the minimum fuel injection amount is determined by the amount that can be stably injected from the injection hole. Therefore, reducing the injection hole area of ​​the injection valve is considered. However, reducing the injection hole area of ​​the injection valve poses the problem of not being able to ensure a sufficient injection amount when the required load increases.

[0005] The present disclosure is intended to solve the above-mentioned problems, and has an object to provide a fuel injection device and a reciprocating internal combustion engine that can increase or decrease the fuel injection amount as needed. [Means for solving the problem]

[0006] To achieve the above object, the fuel injection device of the present disclosure includes a fuel injection valve having a first needle valve and a second needle valve, a first fuel supply path that supplies fuel to the first needle valve, a second fuel supply path that supplies fuel to the second needle valve, and an on-off valve provided in at least one of the first fuel supply path and the second fuel supply path.

[0007] A reciprocating internal combustion engine of the present disclosure includes an internal combustion engine body having a combustion chamber, and the fuel injection device according to claim 1 that injects fuel into the combustion chamber. [Effects of the Invention]

[0008] According to the fuel injection device and reciprocating internal combustion engine of the present disclosure, the fuel injection amount can be increased or decreased as needed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a marine diesel engine according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of the fuel injection device of the first embodiment. [Figure 3] FIG. 3 is a schematic diagram showing the operation of the fuel injection device. [Figure 4] FIG. 4 is a schematic diagram showing the configuration of a fuel injection device according to the second embodiment. [Figure 5] FIG. 5 is a cross-sectional view showing a fuel injection valve. [Figure 6] FIG. 6 is a schematic diagram showing the operation of the fuel injection valve when the on-off valve is open. [Figure 7] FIG. 7 is a time chart showing the operation of the fuel injection valve when the on-off valve is open. [Figure 8]FIG. 8 is a schematic diagram showing the operation of the fuel injection valve when the on-off valve is closed. [Figure 9] FIG. 9 is a time chart showing the operation of the fuel injection valve when the on-off valve is closed. [Figure 10] FIG. 10 is a time chart showing the operation of the fuel injection valve during the opening and closing operation of the on-off valve. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

[0011] [First embodiment] <Marine diesel engine> Fig. 1 is a schematic diagram showing a marine diesel engine according to a first embodiment. In the first embodiment, a marine diesel engine will be described as a reciprocating internal combustion engine. However, the reciprocating internal combustion engine is not limited to a marine diesel engine.

[0012] As shown in FIG. 1, a marine diesel engine 10 is used, for example, as a main engine for propelling a ship, and is a two-stroke, one-cycle, uniflow scavenging crosshead internal combustion engine.

[0013] The marine diesel engine 10 has a diesel engine body (internal combustion engine body) 11. The diesel engine body 11 includes a cylinder liner 12, a piston 13, a scavenging trunk 14, an exhaust manifold 15, and an exhaust valve 16.

[0014] The cylinder liner 12 is cylindrical and is disposed inside a cylinder jacket (not shown), with a cylinder cover 21 fixed to the top. The piston 13 is cylindrical and is disposed inside the cylinder liner 12 and is supported so as to be freely movable in the axial direction. The lower end of the piston 13 is connected to the upper end of a piston rod 22. Although not shown, a crankshaft is rotatably supported at the bottom of the diesel engine body 11, and the lower end of a connecting rod is rotatably connected to the crank via a crank. The diesel engine body 11 supports a crosshead so as to be freely movable in the vertical direction, and the lower end of the piston rod 22 and the upper end of the connecting rod are rotatably connected to the crosshead.

[0015] The scavenging trunk 14 is connected to the lower part of the cylinder liner 12. The cylinder liner 12 communicates with the inside of the scavenging trunk 14 through a plurality of scavenging ports 23. Air is supplied to the scavenging trunk 14 through an intake pipe 24.

[0016] The cylinder liner 12 has an upper space to which a cylinder cover 21 is fixed, which is partitioned by the upper surface of the piston 13, thereby forming a combustion chamber 25. The cylinder cover 21 is connected to the exhaust manifold 15 via an exhaust pipe 26. That is, the combustion chamber 25 communicates with the exhaust manifold 15 via the exhaust pipe 26. The cylinder cover 21 is provided with an exhaust valve 16. The exhaust valve 16 is driven by a valve train 27 to open and close the exhaust pipe 26. When the exhaust valve 16 opens the exhaust pipe 26, the combustion chamber 25 communicates with the exhaust manifold 15 via the exhaust pipe 26.

[0017] The marine diesel engine 10 also includes a fuel injection device 17. The fuel injection device 17 has a fuel supply device 31, a fuel supply path 32, and a fuel injection valve 33. The fuel injection valve 33 is attached to the cylinder cover 21. The fuel injection valve 33 can inject fuel into the combustion chamber 25. The fuel supply device 31 is connected to the fuel injection valve 33 via the fuel supply path 32. The fuel supply device 31 can supply fuel stored in a fuel tank (not shown) to the fuel injection valve 33 via the fuel supply path 32.

[0018] First, when the piston 13 moves to the bottom dead center (the position indicated by the solid line in FIG. 1), the scavenging ports 23 open and the air in the scavenging trunk 14 is introduced through the scavenging ports 23 into the combustion chamber 25. Next, when the piston 13 moves up, the piston 13 blocks communication between the scavenging ports 23 and the combustion chamber 25. At this time, the exhaust valve 16 moves up by the valve train 27, the exhaust pipe 26 is closed, and the air in the combustion chamber 25 is compressed by the movement of the piston 13. Then, when the piston 13 moves to the top dead center (the position indicated by the two-dot chain line in FIG. 1), the pressure in the combustion chamber 25 reaches a predetermined compression pressure, and the fuel injection valve 33 is actuated to inject fuel into the combustion chamber 25. Then, the air and fuel mix and burn in the combustion chamber 25, and the combustion energy moves the piston 13 down. At this time, the exhaust valve 16 moves down by the valve train 27, opening the exhaust pipe 26. Then, exhaust gas generated by the combustion is pushed out from the combustion chamber 25 through the exhaust pipe 26 into the exhaust manifold 15 and discharged.

[0019] <Configuration of fuel injection system> FIG. 2 is a schematic diagram showing the configuration of the fuel injection device of the first embodiment.

[0020] As shown in Fig. 2, fuel injection device 17 is capable of injecting fuel having a predetermined ignition quality (a fossil fuel, for example, light oil or heavy oil as diesel fuel). Fuel injection device 17 includes a fuel supply device 31, a fuel supply path 32, and a fuel injection valve 33. Fuel supply device 31 includes a fuel supply source 41 and a supply pump 42. Fuel supply path 32 includes a main fuel supply path 43, a first fuel supply path 44, and a second fuel supply path 45. Fuel injection valve 33 includes a first needle valve 46, a second needle valve 47, and an on-off valve 48.

[0021] A fuel supply source 41 and a supply pump 42 are connected to the upstream end of main fuel supply path 43 in the fuel supply direction. Fuel supply source 41 is composed of, for example, a fuel accumulator and a pressure pump that pressurizes the fuel. Fuel supply source 40 supplies fuel at a predetermined pressure to the upstream side of main fuel supply path 43. Supply pump 42 is connected to main fuel supply path 43 downstream of fuel supply source 41. Supply pump 42 pressurizes the fuel on the upstream side of main fuel supply path 43 to a predetermined pressure and supplies it to the downstream side of main fuel supply path 43.

[0022] The supply pump 42 has a piston 51 and a plunger 52. The piston 51 and the plunger 52 are connected to each other, and the plunger 52 is connected to the main fuel supply path 43. The piston 51 is connected to a working fluid source 54 via a working oil supply path 53, and the working oil supply path 53 is provided with a control valve (solenoid valve) 55. The working fluid source 54 supplies working fluid at a predetermined pressure to the working oil supply path 53. The supply pump 42 is set so that the pressure-receiving area of ​​the plunger 52 is smaller than the pressure-receiving area of ​​the piston 51, and functions as a booster pump. In addition, the control valve 55 is connected to a control unit 56, and opens and closes in response to commands from the control unit 56.

[0023] When control valve 55 is opened, working fluid from working fluid source 54 is supplied to piston 51 through working oil supply path 53. Piston 51 operates upon receiving the supply of working fluid, thereby actuating plunger 52. Then, supply pump 42 pressurizes the fuel in main fuel supply path 43. At this time, supply pump 42 operates by increasing the pressure of the working fluid, and thus pressurizes the fuel to a predetermined pressure.

[0024] A first fuel supply path 44 and a second fuel supply path 45 are connected to the downstream side of the main fuel supply path 43. That is, the fuel supply path 32 is branched into two paths on the downstream side of the main fuel supply path 43, and the first fuel supply path 44 and the second fuel supply path 45 are provided.

[0025] The downstream end of first fuel supply path 44 is connected to first needle valve 46. First needle valve 46 has a valve body 46a, a biasing spring 46b, a chamber 46c, a fuel supply path 46d, a nozzle hole 46e, and a sliding seal 46f. First fuel supply path 44 is connected to chamber 46c. Chamber 46c is in communication with fuel supply path 46d, which has nozzle hole 46e formed at its tip. Valve body 46a is seated by the biasing force of biasing spring 46b, thereby blocking communication between chamber 46c and fuel supply path 46d. A predetermined first injection pressure is set in first needle valve 46. Therefore, when fuel at a pressure higher than the first injection pressure is supplied from first fuel supply path 44 to chamber 46c, valve element 46a of first needle valve 46 rises against the biasing force of biasing spring 46b, connecting chamber 46c to fuel supply path 46d. The fuel supplied to chamber 46c then flows into fuel supply path 46d and is injected from nozzle hole 46e.

[0026] The downstream end of second fuel supply path 45 is connected to second needle valve 47. Second needle valve 47 has a valve body 47a, a biasing spring 47b, a chamber 47c, a fuel supply path 47d, a nozzle hole 47e, and a sliding seal portion 47f. Second fuel supply path 45 is connected to chamber 47c. Chamber 47c is in communication with fuel supply path 47d, which has a nozzle hole 47e formed at its tip. Valve body 47a is seated by the biasing force of biasing spring 47b, thereby blocking communication between chamber 47c and fuel supply path 47d. A predetermined second injection pressure is set in second needle valve 47. Therefore, when fuel at a pressure higher than the second injection pressure is supplied from second fuel supply path 45 to chamber 47c, valve element 47a of second needle valve 47 rises against the biasing force of biasing spring 47b, connecting chamber 47c to fuel supply path 47d. The fuel supplied to chamber 47c then flows into fuel supply path 47d and is injected from nozzle hole 47e.

[0027] The areas of the nozzle holes 46e and 47e of the first needle valve 46 and the second needle valve 47 are different. The area of ​​the nozzle hole 46e of the first needle valve 46 is smaller than the area of ​​the nozzle hole 47e of the second needle valve 47. When the first needle valve 46 and the second needle valve 47 inject 100% of the fuel, for example, the first needle valve 46 injects 5% of the total fuel, and the second needle valve 47 injects 95% of the total fuel. The area of ​​the nozzle hole 46e of the first needle valve 46 and the area of ​​the nozzle hole 47e of the second needle valve 47 are not limited to the ratio described above and may be set as appropriate.

[0028] The on-off valve 48 is provided in the second fuel supply path 45. However, the on-off valve 48 may be provided in the first fuel supply path 44, or may be provided in both the first fuel supply path 44 and the second fuel supply path 45.

[0029] The on-off valve 48 has a cylinder 61 and a piston 62. In the on-off valve 48, the piston 62 is supported relative to the cylinder 61 so as to be freely movable in the axial direction. The piston 62 can open and close the second fuel supply path 45 with a tip end. When the tip end of the piston 62 is positioned in the second fuel supply path 45, the on-off valve 48 closes the second fuel supply path 45, and when the tip end is separated from the second fuel supply path 45, the on-off valve 48 opens the second fuel supply path 45.

[0030] In the on-off valve 48, a cylinder 61 is connected to a hydraulic fluid source 64 via a hydraulic fluid supply path 63, and a control valve (solenoid valve) 65 is provided in the hydraulic fluid supply path 63. The hydraulic fluid source 64 supplies hydraulic fluid at a predetermined pressure to the hydraulic fluid supply path 63. In addition, the control unit 56 is connected to the control valve 65, and the control valve 65 opens and closes in response to commands from the control unit 56.

[0031] When the control valve 65 is opened, the working fluid from the working fluid source 64 is supplied to the cylinder 61 through the working oil supply path 63. The piston 62 receives the working fluid supplied to the cylinder 61 and operates. Then, the piston 62 moves in the on-off valve 48, closing the second fuel supply path 45.

[0032] A check valve 71 is provided in main fuel supply path 43 between the connection portion of supply pump 42 and the branch portion of first fuel supply path 44 and second fuel supply path 45. Check valve 71 prevents fuel from flowing back toward supply pump 42. Also, a check valve 72 is provided in main fuel supply path 43 between the connection portion of supply pump 42 and fuel supply source 41. Check valve 72 prevents fuel from flowing back from the connection portion of supply pump 42 toward fuel supply source 41.

[0033] Main fuel supply path 43 is provided with a return path 73 that branches off from a path between the branch point of first fuel supply path 44 and second fuel supply path 45 and check valve 71. Return path 73 bypasses check valves 71 and 72 and supply pump 42. Return path 73 is provided with a check valve 74. Check valve 74 allows fuel to be returned from main fuel supply path 43 to the fuel supply source 41 side via return path 73 and prevents fuel from being supplied from the fuel supply source 41 to main fuel supply path 43.

[0034] <Fuel injection system operation> FIG. 3 is a schematic diagram showing the operation of the fuel injection device.

[0035] 2, when the control valve 65 is opened, the working fluid from the working fluid source 64 is supplied to the cylinder 61 of the on-off valve 48 through the working oil supply path 63. Then, the piston 62 of the on-off valve 48 moves relative to the cylinder 61, closing the second fuel supply path 45. At this time, when the control valve 55 is opened, the working fluid from the working fluid source 54 is supplied to the supply pump 42 through the working oil supply path 53. Then, the piston 51 of the supply pump 42 operates to operate the plunger 52, and the fuel in the main fuel supply path 43 is pressurized.

[0036] Fuel from fuel supply source 41 is pressurized by supply pump 42 and supplied to main fuel supply path 43 through check valve 71. The fuel from main fuel supply path 43 is supplied to first fuel supply path 44 and second fuel supply path 45. At this time, second fuel supply path 45 is closed by on-off valve 48. Therefore, no fuel is supplied to second needle valve 47, and no fuel is injected. On the other hand, first needle valve 46 is supplied with fuel at a pressure higher than the first injection pressure from first fuel supply path 44, and injects a small amount of fuel.

[0037] 3, when the control valve 65 is closed, the working fluid from the working fluid source 64 is not supplied to the cylinder 61 of the on-off valve 48 through the working oil supply path 63. Therefore, the piston 62 of the on-off valve 48 does not move relative to the cylinder 61, and the second fuel supply path 45 is opened. At this time, when the control valve 55 is opened, the working fluid from the working fluid source 54 is supplied to the supply pump 42 through the working oil supply path 53. Then, the piston 51 of the supply pump 42 operates to operate the plunger 52, and the fuel in the main fuel supply path 43 is pressurized.

[0038] Fuel from fuel supply source 41 is pressurized by supply pump 42 and supplied to main fuel supply path 43 through check valve 71. The fuel from main fuel supply path 43 is supplied to first fuel supply path 44 and second fuel supply path 45. At this time, second fuel supply path 45 is opened by on-off valve 48. Therefore, when fuel at a pressure higher than the first injection pressure is supplied from first fuel supply path 44, first needle valve 46 injects a small amount of fuel. On the other hand, when fuel at a pressure higher than the second injection pressure is supplied from second fuel supply path 45, second needle valve 47 injects a large amount of fuel.

[0039] [Second embodiment] Fig. 4 is a schematic diagram showing the configuration of a fuel injection device of the second embodiment, and Fig. 5 is a cross-sectional view showing a fuel injection valve. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals and detailed descriptions thereof will be omitted.

[0040] 4, fuel injection device 17A includes fuel supply device 31, fuel supply path 32, and fuel injection valve 33A. Fuel supply device 31 has a fuel supply source 41 and a supply pump 42. Fuel supply path 32 has a main fuel supply path 43, a first fuel supply path 44, and a second fuel supply path 45. Fuel injection valve 33A includes a needle valve 80 including a first needle valve 81 and a second needle valve 82, and an on-off valve 48.

[0041] As shown in FIGS. 4 and 5 , the needle valve 80 has a first needle valve 81 and a second needle valve 82. The first needle valve 81 and the second needle valve 82 are supported axially movably relative to a main body 83. The main body 83 is provided with a first nozzle hole 91 and a second nozzle hole 92 at radially different positions at its tip end (the lower end in FIG. 5 ). The first nozzle holes 91 are provided in plurality at circumferential intervals toward the tip end of the main body 83. The second nozzle holes 92 are provided in plurality at circumferential intervals toward the base end (the upper end in FIG. 5 ) of the main body 83. The first nozzle holes 91 communicate with a first chamber 93, and the second nozzle holes 92 communicate with a second chamber 94. The main body 83 is further provided with a third chamber 95 at an upper end thereof than the second chamber 94. Each of the chambers 93, 94, and 95 has a ring shape extending along the circumferential direction. The first needle valve 81 and the second needle valve 82 have different areas of the first nozzle hole 91 and the second nozzle hole 92. The area of ​​one first nozzle hole 91 of the first needle valve 81 is smaller than the total area of ​​the second nozzle holes 92 of the multiple second needle valves 82.

[0042] The first needle valve 81 is cylindrical and has a first fuel flow path 101 formed on its outer periphery along the axial direction. The second needle valve 82 is cylindrical and has a second fuel flow path 102 formed on its tip. The second needle valve 82 is disposed inside the main body 83, and the first needle valve 81 is disposed inside the second needle valve 82. The first needle valve 81 and the second needle valve 82 are disposed concentrically with the main body 83 and supported so as to be movable relative to each other. The first needle valve 81 is biased toward its tip by the biasing force of a biasing spring 103. As a result, the outer surface of the tip of the first needle valve 81 is in close contact with the inner surface of the tip of the second needle valve 82, and the outer surface of the tip of the second needle valve 82 is in close contact with the inner surface of the main body 83. At this time, the first seat S1 blocks communication between the first fuel flow path 101 of the first needle valve 81 and the second fuel flow path 102 of the second needle valve 82. Additionally, the second seat portion S2 blocks communication between the second chamber 94 and the third chamber 95 of the main body 83. Furthermore, the third seat portion S3 blocks communication between the second chamber 94 of the main body 83 and the second fuel flow path 102 of the first chamber 93.

[0043] Second needle valve 82 is provided with a ring-shaped reservoir 104 facing the outlet of first fuel flow path 101, between it and first needle valve 81. Second needle valve 82 is provided with an inclined surface 105 so that the gap between it and first needle valve 81 increases from reservoir 104 toward second fuel flow path 102. First seat S1 is provided in a ring shape between reservoir 104 and inclined surface 105. Second needle valve 82 is provided with an inclined surface 106 so that the gap between it and main body 83 decreases from third chamber 95 to second chamber 94. Second needle valve 82 is provided with an inclined surface 107 so that the gap between it and main body 83 increases from second chamber 94 to second fuel flow path 102.

[0044] The first fuel supply path 44 communicates with the first fuel flow path 101 , and the second fuel supply path 45 communicates with the third chamber 95 .

[0045] The biasing force of biasing spring 103 causes first needle valve 81 to tightly contact second needle valve 82, which in turn tightly contacts main body 83. In this state, when fuel from first fuel supply path 44 is supplied to first fuel flow path 101 of first needle valve 81, first needle valve 81 rises relative to second needle valve 82. This opens first seat S1, allowing fuel in first fuel flow path 101 to flow to second fuel flow path 102 of second needle valve 82 and be supplied to first chamber 93, causing fuel to be injected from multiple first nozzle holes 91.

[0046] When fuel from second fuel supply path 45 is supplied to third chamber 95, second needle valve 82 of needle valve 80 rises relative to main body 83. This opens second seat S2 and third seat S3, allowing fuel in third chamber 95 to be supplied to second chamber 94 and first chamber 93, and fuel is injected from first nozzle holes 91 and second nozzle holes 92. At this time, first seat S1 is closed, blocking the flow of fuel from first fuel passage 101 of first needle valve 81 to second fuel passage 102 of second needle valve 82.

[0047] <Fuel injection valve operation> Figure 6 is a schematic diagram showing the operation of the fuel injection valve when the on-off valve is open, Figure 7 is a time chart showing the operation of the fuel injection valve when the on-off valve is open, Figure 8 is a schematic diagram showing the operation of the fuel injection valve when the on-off valve is closed, Figure 9 is a time chart showing the operation of the fuel injection valve when the on-off valve is closed, and Figure 10 is a time chart showing the operation of the fuel injection valve during the opening and closing operation of the on-off valve.

[0048] 6 and 7, when control valve 65 is closed, working fluid from working fluid source 64 is not supplied to cylinder 61 of on-off valve 48 through working oil supply path 63. Therefore, on-off valve 48 does not move and opens second fuel supply path 45. At this time, when supply pump 42 operates, it pressurizes the fuel in main fuel supply path 43. Then, high-pressure fuel is supplied from main fuel supply path 43 to first fuel supply path 44 and second fuel supply path 45. Second fuel supply path 45 is opened by on-off valve 48, and first needle valve 46 and second needle valve 47 inject fuel at the same time.

[0049] 8 and 9, when control valve 65 is open, working fluid from working fluid source 64 is supplied to cylinder 61 of on-off valve 48 through working oil supply path 63. Then, piston 62 of on-off valve 48 moves relative to cylinder 61, closing second fuel supply path 45. At this time, supply pump 42 operates to pressurize fuel in main fuel supply path 43. Then, high-pressure fuel is supplied from main fuel supply path 43 to first fuel supply path 44 and second fuel supply path 45. Second fuel supply path 45 is closed by on-off valve 48, and first needle valve 46 injects fuel, but fuel is not supplied to second needle valve 47, so fuel is not injected.

[0050] As shown in FIG. 10 , when the control valve 65 is open (ON), the working fluid from the working fluid source 64 is supplied to the cylinder 61 of the on-off valve 48 through the working oil supply path 63. The on-off valve 48 then closes the second fuel supply path 45. When the supply pump 42 operates at this time, it pressurizes the fuel in the main fuel supply path 43, and the high-pressure fuel is supplied from the main fuel supply path 43 to the first fuel supply path 44 and the second fuel supply path 45. Since the second fuel supply path 45 is then closed by the on-off valve 48, only the first needle valve 46 injects fuel. In this case, by changing the fuel injection amount during the fuel injection period, the fuel injection amount in the later period can be increased, improving the trade-off between improved fuel economy and reduced emissions of harmful substances (NOx).

[0051] When only first needle valve 46 is injecting fuel, opening control valve 65 (FF) stops the supply of working fluid to on-off valve 48, which then returns to its original position and opens second fuel supply path 45. Then, because second fuel supply path 45 is opened by on-off valve 48, first needle valve 46 and second needle valve 47 inject fuel. As a result, the amount of fuel injected by fuel injection valve 33A is increased from the amount of fuel injected by first needle valve 46 to the combined amount of fuel injected by first needle valve 46 and second needle valve 47.

[0052] [Effects of this embodiment] The fuel injection device according to the first aspect includes a fuel injection valve (33, 33A) having a first needle valve (46, 81) and a second needle valve (47, 82), a first fuel supply path (44) that supplies fuel to the first needle valve (46, 81), a second fuel supply path (45) that supplies fuel to the second needle valve (47, 82), and an on-off valve (48) provided in at least one of the first fuel supply path (44) and the second fuel supply path (45).

[0053] According to the fuel injection device of the first aspect, fuel injection from the first needle valve 46, 81 and the second needle valve 47, 82 can be switched on and off by controlling the on-off valve 48, thereby easily adjusting the fuel injection amount from the fuel injection valve 33, 33A. As a result, the fuel injection amount can be increased or decreased as needed. For example, in a fuel injection device 17, 17A that injects one type of fuel, the fuel injection amount can be increased or decreased depending on the required load, reducing the minimum injection amount that can be stably injected, thereby improving combustibility immediately after engine startup. In other words, when using a carbon-containing fuel such as diesel or heavy oil as fuel, the generation of black smoke can be suppressed. Furthermore, in a fuel injection device 17, 17A that injects two types of fuel, if a carbon-free fuel with poor ignition and combustibility is injected as the main fuel, the fuel injection device 17, 17A can be used as a fuel injection device that injects a fuel with good ignition ability as the pilot fuel.

[0054] The fuel injection device according to the second aspect is the fuel injection device according to the first aspect, further comprising a difference in nozzle hole area between first needle valve 46, 81 and second needle valve 47, 82. This allows, for example, first needle valve 46, 81 to inject a smaller amount of fuel.

[0055] The fuel injection device according to the third aspect is the fuel injection device according to the first or second aspect, and further includes a working fluid source 64, a hydraulic oil supply path 63 connecting the working fluid source 64 and the on-off valve, and a control valve 65 provided in the working oil supply path 63. As a result, the on-off valve 48 can be easily controlled to open and close simply by controlling the control valve 65 to turn on and off.

[0056] A fuel injection device according to a fourth aspect is the fuel injection device according to the first or second aspect, and further includes fuel injection valve 33A having main body 83 with nozzle holes 91, 92 at its tip, first needle valve 81 movably provided inside main body 83 and capable of connecting first fuel supply path 44 to nozzle hole 91 depending on its position, and second needle valve 82 movably provided between main body 83 and first needle valve 81 and capable of connecting second fuel supply path 45 to nozzle holes 91, 92 depending on its position. Thus, by using needle valve 80 having first needle valve 81 and second needle valve 82, fuel injection valve 33A can be simplified.

[0057] A fuel injection device according to a fifth aspect is the fuel injection device according to the fourth aspect, further comprising: main body 83, first needle valve 81, and second needle valve 82 that are concentric and relatively movable in the axial direction; when first needle valve 81 moves away from second needle valve 82, first fuel supply path 44 communicates with nozzle hole 91 to inject fuel; and when second needle valve 82 moves away from main body 83, second fuel supply path 45 communicates with nozzle holes 91, 92 to inject fuel. Thus, movement of first needle valve 81 relative to main body 83 allows fuel to be injected from first nozzle hole 91, and movement of second needle valve 82 allows fuel to be injected from first nozzle hole 91 and second nozzle hole 92.

[0058] A fuel injection device according to a sixth aspect is the fuel injection device according to the fourth or fifth aspect, further including first injection holes 91 positioned at intervals in the circumferential direction and second injection holes 92 positioned at intervals in the circumferential direction and shifted in the circumferential direction or axial direction from the first injection holes 91, wherein the first fuel supply path 44 can communicate with the first injection holes 91, and the second fuel supply path 45 can communicate with the first injection holes 91 and the second injection holes 92. This makes it possible to easily adjust the fuel injection amount by switching between injecting and stopping fuel from the first injection holes 91 and the second injection holes 92.

[0059] A fuel injection device according to a seventh aspect is the fuel injection device according to any one of the fourth to sixth aspects, further comprising: first needle valve 81 having a first fuel flow path 101 that extends along the axial direction and has a base end that communicates with first fuel supply path 44 and an open tip end; second needle valve 82 having a second fuel flow path 102 that penetrates along the axial direction; and first seat S1 provided between the tip end of first fuel flow path 101 and the base end of second fuel flow path 102. This allows fuel injection to be started and stopped appropriately by movement of first needle valve 81.

[0060] A fuel injection device according to an eighth aspect is the fuel injection device according to the seventh aspect, further comprising: main body 83 having a first chamber 93 in which first nozzle hole 91 is formed, a second chamber 94 in which second nozzle hole 92 is formed, and a third chamber 95 with which second fuel supply path 45 communicates; second seat portion S2 is provided between second chamber 94 and third chamber 95; first seat portion S1 can be opened and closed in response to movement of first needle valve 81; and second seat portion S2 can be opened and closed in response to movement of second needle valve 82. This allows fuel injection to be appropriately started and stopped by movement of second needle valve 82.

[0061] A fuel injection device according to a ninth aspect is the fuel injection device according to any one of the sixth to eighth aspects, and further characterized in that when first needle valve 81 and second needle valve 82 are in their lowered positions, first fuel supply passage 44 and second fuel supply passage 45 do not communicate with first nozzle hole 91, when first needle valve 81 is in their raised position, first fuel supply passage 44 communicates with first nozzle hole 91, and when second needle valve 82 is in their raised position, second fuel supply passage 45 communicates with first nozzle hole 91 and second nozzle hole 92. This makes it possible to easily adjust the amount of fuel injection according to the positions of first needle valve 81 and second needle valve 82.

[0062] A reciprocating internal combustion engine according to a tenth aspect includes a diesel engine body 11 having a combustion chamber 25, and a fuel injection device 17, 17A according to any one of the first to ninth aspects that injects fuel into the combustion chamber 25. This allows the amount of fuel injection to be increased or decreased as needed. [Explanation of symbols]

[0063] 10 Marine diesel engines (reciprocating internal combustion engines) 11 Diesel engine body (internal combustion engine body) 12 Cylinder liner 13 Piston 14 Scavenging trunk 15 Exhaust manifold 16 Exhaust valve 17,17A fuel injection device 31 Fuel supply system 32 Fuel supply route 33,33A Fuel injection valve 41 Fuel supply source 42 Supply Pump 43 Main fuel supply line 44 First fuel supply route 45 Second fuel supply route 46 First needle valve 47 Second needle valve 51 Piston 52 Plunger 53 Hydraulic oil supply path 54 Working fluid source 55 Control valve 56 Control Unit 61 cylinders 62 Piston 63 Hydraulic oil supply path 64 Working fluid source 65 Control valve 71,74 Check valve 80 Needle valve 81 First needle valve 82 Second needle valve 83 Main Unit 91 No. 1 nozzle 92 No. 2 nozzle 93 Chamber 1 94 Second Chamber 95 Third Chamber 101 First fuel flow path 102 Second fuel flow path

Claims

1. a fuel injection valve having a first needle valve and a second needle valve; a first fuel supply path that supplies fuel to the first needle valve; a second fuel supply path that supplies fuel to the second needle valve; an on-off valve provided in at least one of the first fuel supply path and the second fuel supply path; A fuel injection device comprising:

2. The first needle valve and the second needle valve have different nozzle hole areas.

2. The fuel injection system of claim 1.

3. a hydraulic oil supply source; a hydraulic oil supply path connecting the hydraulic oil supply source and the on-off valve; and a control valve provided in the hydraulic oil supply path.

3. A fuel injection device according to claim 1 or 2.

4. the fuel injection valve includes: a body having a nozzle hole at a tip end thereof; a first needle valve movably provided inside the body and capable of connecting the first fuel supply path to the nozzle hole depending on a position of the first needle valve; and a second needle valve movably provided between the body and the first needle valve and capable of connecting the second fuel supply path to the nozzle hole depending on a position of the second needle valve.

2. The fuel injection system of claim 1.

5. the main body, the first needle valve, and the second needle valve are concentric and relatively movable in the axial direction; when the first needle valve moves away from the second needle valve, the first fuel supply path communicates with the nozzle hole to inject fuel; and when the second needle valve moves away from the main body, the second fuel supply path communicates with the nozzle hole to inject fuel.

5. The fuel injection system of claim 4.

6. the nozzle holes include first nozzle holes positioned at intervals in the circumferential direction and second nozzle holes positioned at intervals in the circumferential direction and shifted in the circumferential direction or the axial direction from the first nozzle holes, the first fuel supply path being capable of communicating with the first nozzle holes, and the second fuel supply path being capable of communicating with the first nozzle holes and the second nozzle holes; 6. A fuel injection device according to claim 4 or claim 5.

7. The first needle valve has a first fuel passage that extends along the axial direction, a base end that communicates with the first fuel supply path, and an open tip end. The second needle valve has a second fuel passage that penetrates along the axial direction, and a first seat portion is provided between the tip end of the first fuel passage and the base end of the second fuel passage.

7. The fuel injection system of claim 6.

8. the main body has a first chamber in which the first nozzle hole is formed, a second chamber in which the second nozzle hole is formed, and a third chamber to which the second fuel supply path is connected, and a second seat portion is provided between the second chamber and the third chamber, the first seat portion being openable and closable in response to movement of the first needle valve, and the second seat portion being openable and closable in response to movement of the second needle valve; 8. A fuel injection system according to claim 7.

9. when the first needle valve and the second needle valve are in their lowered positions, the first fuel supply path and the second fuel supply path do not communicate with the first nozzle hole, when the first needle valve is in its raised position, the first fuel supply path communicates with the first nozzle hole, and when the second needle valve is in its raised position, the second fuel supply path communicates with the first nozzle hole and the second nozzle hole.

9. The fuel injection system of claim 8.

10. an internal combustion engine body having a combustion chamber; a fuel injection device according to claim 1 for injecting fuel into the combustion chamber; A reciprocating internal combustion engine comprising:

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