KR101854058B1 - Liquid fuel supply system - Google Patents

Abstract

The liquid fuel supply system 20 has a injection valve 9 for injecting the liquid fuel FO into the combustion chamber 7 and a control device for adjusting the injection pressure of the liquid fuel injected into the combustion chamber 26 at the injection valve . The injection pressure includes the injection pressure at the start of the liquid fuel when the injection of the liquid fuel from the injection valve is started. The control device adjusts such that the injection pressure at the start according to the gas mode in which both the liquid fuel and the gaseous fuel are supplied to the combustion chamber is higher than the injection pressure at the start according to the diesel mode in which the liquid fuel is supplied to the combustion chamber and the gaseous fuel is not supplied .

Description

[0001] LIQUID FUEL SUPPLY SYSTEM [0002]

The present invention relates to a liquid fuel supply system of a dual fuel engine.

For example, a dual fuel engine (dual fuel engine) is known in which power is generated by using both liquid fuel and gaseous fuel as disclosed in Patent Document 1 as a power source of a ship.

Japanese Patent No. 3432098

The dual fuel engine is operable in each of the diesel mode (fuel oil only mode) using only liquid fuel (fuel oil) and the gas mode (two fuel mode) using both liquid fuel and gaseous fuel (combustible gas) . The diesel mode is a method of supplying liquid fuel to the combustion chamber and burning the supplied liquid fuel. The gas mode is a method in which gaseous fuel supplied at a certain timing to the combustion chamber is ignited and burned based on a pilot flame generated by a small amount of liquid fuel supplied to the combustion chamber.

If the control of the supply amount of the liquid fuel for generating the pilot flame in the gas mode is not performed with high precision, the performance of the dual fuel engine may deteriorate. For example, if the supply amount of the liquid fuel is excessive, the consumption amount of the liquid fuel increases and the possibility of generation of NOx increases. On the other hand, if the supply amount of the liquid fuel is too small, it may become difficult to stably supply a certain amount of the liquid fuel, or foreign substances may adhere to the injection port of the liquid fuel, and the liquid fuel may not be supplied smoothly.

An object of the present invention is to provide a liquid fuel supply system of a dual fuel engine capable of stably supplying a small amount of liquid fuel.

A liquid fuel supply system according to the present invention is a liquid fuel supply system for supplying a liquid fuel to a combustion chamber of a dual fuel engine, comprising: an injection valve for injecting the liquid fuel into the combustion chamber; Wherein the injection pressure includes an injection pressure at the start of the liquid fuel when the injection of the liquid fuel from the injection valve is started and the control device includes a control device capable of adjusting the injection pressure of the fuel, Injection pressure in accordance with the gas mode in which both the liquid fuel and the gaseous fuel are supplied is higher than the starting-time injection pressure in accordance with the diesel mode in which the liquid fuel is supplied to the combustion chamber and the gaseous fuel is not supplied to the combustion chamber Adjust.

According to the present invention, when the liquid fuel is injected into the combustion chamber, the injection pressure at the start of the liquid fuel when the injection of the liquid fuel from the injection valve is started is adjusted so that the gas mode is higher than the diesel mode, It is possible to stably supply a small amount of liquid fuel while suppressing adhesion of foreign matter to the injection port.

In the liquid fuel supply system according to the present invention, a pump capable of supplying the liquid fuel to the injection valve with a piston, a high-pressure passage filled with a working liquid capable of operating the piston, and a high- A main valve disposed at the inside position to close the high pressure passage and disposed at the outside position to open the high pressure passage; and a high pressure passage connected to the high pressure passage, A supply passage through which the working liquid supplied to the main valve flows in the passage, a spill passage connectable with the supply passage, and a state in which the main valve is disposed at the inner position by connecting the supply passage and the high- The main valve is connected to the spill passage and the supply passage is connected to the other side A main electromagnetic valve which is disposed in the spill passage and which adjusts a flow rate of the working fluid flowing out of the supply passage so as to move the main valve from the inner position to the outer position, Wherein the control device controls the main solenoid valve and the sub solenoid valve and adjusts the injection pressure, and in the diesel mode, the main valve is operated at the first speed And controls the main solenoid valve and the sub solenoid valve so that in the gas mode, the main valve moves at the second position at a second speed higher than the first speed, the diesel mode and the gas mode It is also possible to adjust the injection pressure at the initiation according to each of them. In the liquid fuel supply system provided with the main solenoid valve and the sub solenoid valve, the main valve is moved by the operation of the main solenoid valve to open / close the high-pressure passage. The supply passage and the high-pressure passage are connected to supply the working liquid to the main valve, so that the main valve moves to the inside of the high-pressure passage and closes the high-pressure passage. On the other hand, the supply passage and the spill passage are connected, and the working liquid of the supply passage flows out to the spill passage, so that the main valve moves to the outside of the high-pressure passage and opens the high-pressure passage. As a result, the piston of the pump is operated to supply the liquid fuel to the injection valve, and the liquid fuel is injected from the injection valve. A sub-solenoid valve is disposed in the spill passage. When the main valve moves so as to open the high pressure passage, the sub solenoid valve adjusts the flow rate of the working fluid flowing out of the supply passage. The flow rate of the working fluid is adjusted to adjust the moving speed of the main valve. In the gas mode, the main valve moves from the high pressure passageway to the second, high speed. As a result, the pressure of the working liquid in the high-pressure passage acting on the piston changes rapidly, and as a result, the liquid fuel is injected at a high speed from the injection valve. Therefore, even when a small amount of liquid fuel is injected from the injection valve, adhesion of foreign matter to the injection port of the injection valve is suppressed, and a small amount of liquid fuel can be stably supplied.

In the liquid fuel supply system according to the present invention, the spill passage includes a quick spill passage and a slow spill passage narrower than the quick spill passage, and the sub-solenoid valve is configured such that the working liquid from the supply passage communicates with the quick spill passage And a state in which the working liquid from the supply passage does not flow through the quick spill passage may be switched from one to another. Working fluid from the supply passage flows to both the quill pencil case and the slow spill passage, so that the working liquid in the supply passage rapidly flows out from the supply passage. As a result, the main valve can be moved on the highway. On the other hand, the working liquid from the supply passage flows only through the slow spill passage, so that the working liquid of the supply passage smoothly flows out from the supply passage. As a result, the main valve can be moved at a low speed.

In the liquid fuel supply system according to the present invention, the sub solenoid valve may include a solenoid. Since the operating speed of the sub solenoid valve is adjusted by the solenoid, the moving speed of the main valve can be finely adjusted.

In the liquid fuel supply system according to the present invention, in the diesel mode, the main valve moves at the first speed in the electricity of the moving period from the inner position to the outer position, and at the second speed You can move at a faster speed than that. By moving the main valve at the first speed at a low speed in the electricity of the main valve moving period, the injection amount (injection ratio) of the liquid fuel injected from the injection valve in the electricity of the injection period in which the liquid fuel is injected is reduced. As a result, the combustion temperature is reduced and, for example, the generation of NOx is suppressed. By moving the main valve at a high speed in the latter period of the movement period of the main valve, the injection quantity increases in the latter period of the injection period and the liquid fuel necessary for combustion in the diesel mode is supplied to the combustion chamber.

The liquid fuel supply system of the dual fuel engine according to the present invention can stably supply a small amount of liquid fuel.

1 is a schematic diagram showing an example of a dual fuel engine according to the present embodiment.
2 is a schematic diagram showing an example of the operation of the dual fuel engine according to the present embodiment.
3 is a plan view schematically showing an example of a state in which fuel is injected into the combustion chamber in the gas mode.
4 is a diagram schematically showing an example of a state in which the fuel is burning in the gas mode.
5 is a plan view schematically showing an example of a state in which fuel is burning in the gas mode.
6 is a cross-sectional view showing an example of the liquid fuel supply system according to the present embodiment.
7 is a diagram showing an example of the operation of the liquid fuel supply system according to the present embodiment.
8 is a diagram showing an example of the operation of the liquid fuel supply system according to the present embodiment.
9 is a diagram showing an example of the operation of the liquid fuel supply system according to the present embodiment.
10 is a diagram showing an example of a sub solenoid valve according to the present embodiment.
11 is a view for explaining an example of the operation of the main solenoid valve and the sub solenoid valve in the diesel mode according to the present embodiment.
12 is a diagram for explaining an example of the operation of the main solenoid valve and the sub solenoid valve according to the gas mode according to the present embodiment.
13 is a view for explaining an example of the operation of the liquid fuel supply system according to the diesel mode according to the present embodiment.
14 is a view for explaining an example of the operation of the liquid fuel supply system according to the diesel mode according to the present embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The requirements of the respective embodiments described below can be appropriately combined. Also, some components may not be used.

1 is a schematic diagram showing an example of a dual-fuel engine 1 according to the present embodiment. The dual fuel engine 1 according to the present embodiment includes a crosshead type diesel engine and is used, for example, as a propulsion engine for a ship or the like.

The dual fuel engine 1 is provided with a base plate 18, a bridge 12 provided on the base plate 18 and a jacket 13 provided on the bridge 12.

The dual fuel engine 1 also includes a cylinder 2 provided in the jacket 13, a piston 3 reciprocating in the cylinder 2, a piston rod 14 connected to the piston 3, A crosshead 16 connecting the piston rod 14 and the connecting rod 19 and a crankshaft 4 connected to the connecting rod 19 via a crank pin 17 .

The cylinder 2 has a cylinder liner 2A provided on the jacket 13 and a cylinder cover 2B provided on the cylinder liner 2A. The crosshead 16 moves along the guide portion 12G provided in the bridge 12 and transmits the mechanical power from the piston rod 14 to the connecting rod 19. The crankshaft 4 is disposed on the base plate 18 and outputs a mechanical power transmitted from the piston 3.

The upper surface of the piston 3 and the ceiling surface of the cylinder 2 face each other. An exhaust valve (11) is provided at the center of the ceiling surface of the cylinder (2). A combustion chamber (7) is formed between the piston (3), the cylinder (2) and the exhaust valve (11).

The dual fuel engine 1 further includes a detection device 6 for detecting the rotation angle (crank angle) of the crankshaft 4, a gaseous fuel injection valve 8 for supplying the gaseous fuel PG to the combustion chamber 7, A liquid fuel supply system 20 including a gaseous fuel supply system 15 including a liquid fuel injection valve 15 for supplying liquid fuel FO to the combustion chamber 7 and a liquid fuel injection valve 9 for supplying liquid fuel FO to the combustion chamber 7, And a control device (10) for controlling the control device (10).

The gaseous fuel injection valve 8 is capable of injecting gaseous fuel PG into the combustion chamber 7. The gaseous fuel PG refers to, for example, one kind or a mixed gas of natural gas and flammable gas such as H ₂ (hydrogen gas). In the present embodiment, two gas fuel injection valves 8 are arranged in the combustion chamber 7. The number of the gaseous fuel injection valves 8 is arbitrary.

The liquid fuel injection valve 9 is capable of injecting the liquid fuel FO into the combustion chamber 7. The liquid fuel (FO) includes, for example, at least one of light oil, heavy oil and heavy oil. In the present embodiment, two liquid fuel injection valves 9 are disposed in the combustion chamber 7. The number of the liquid fuel injection valves 9 is arbitrary.

The detecting device 6 includes a crank angle sensor and detects the crank angle of the crankshaft 4. [ The detection device 6 may detect the crank angle based on the top dead center of the piston 3. [ The crank angle sensor detects a crank angle at a rotational position of a measuring member (a disc, a detecting gear, etc.) mounted on the crankshaft 4, for example, and outputs a crank angle number. The crank angle sensor may be an optical type or an electronic type. Further, the detecting device 6 may detect the crank angle in the rotational position of the crankshaft 4, the position of the piston 3, or the like. Further, position information (reference position information) of the crankshaft 4 when the piston 3 is located at the top dead center is detected using the top dead center sensor, and the position information and the rotational speed information of the crankshaft 4 The crank angle may be obtained.

The detection result of the detection position 6 is outputted to the control device 10. [ The crank angle and the position of the piston 3 are related. The control device 10 can obtain the position of the piston 3 including the top dead center and bottom dead center on the basis of the detection result of the detection device 6. [ Further, the control device 10 can obtain, for example, a time point at which the piston 3 is disposed at the top dead center and a time point at which the piston 3 is disposed at the bottom dead point based on the output of the built- have. The controller 10 controls the opening and closing of the exhaust valve 11, the injection of the gaseous fuel PG from the gaseous fuel injection valve 8 and the injection of the liquid fuel FO from the liquid fuel injection valve 9, based on the crank angle. And outputs a command signal for controlling the injection of fuel.

Fig. 2 is a schematic diagram showing an example of the operation of the dual fuel engine 1. Fig. In the present embodiment, the dual fuel engine 1 is a two-stroke single cycle Uniflow scavenging diesel engine. When the piston 3 is disposed near the top dead center, And the gas in the combustion chamber 7 is discharged from the exhaust port while moving from the top dead center to the bottom dead center. The operation of the dual fuel engine 1 includes an intake process A for injecting fresh air into the combustion chamber 7, a compression process B for compressing the air in the combustion chamber 7 by the piston 3, 7 for injecting fuel to burn the fuel and an exhausting process D for exhausting the gas in the combustion chamber 7 after the combustion process from the exhaust valve 11. [

The dual fuel engine 1 is operable in each of the diesel mode using only the liquid fuel FO and the gas mode using both the liquid fuel FO and the gaseous fuel PG.

The diesel mode is a mode in which the liquid fuel FO is supplied to the combustion chamber 7 and the gaseous fuel PG is not supplied. The diesel mode may be referred to as a fuel-oil-only mode. The diesel mode is a method of injecting the liquid fuel FO into the combustion chamber 7 in the liquid fuel injection valve 9 and burning the injected liquid fuel FO. In the diesel mode, the gaseous fuel PG is not injected into the combustion chamber 7 from the gaseous fuel injection valve 8. In the diesel mode, after the air in the combustion chamber 7 is compressed in the compression process, the liquid fuel FO is injected from the liquid fuel injection valve 9 into the combustion chamber 7 in the combustion process. The liquid fuel FO is spontaneously ignited by burning the liquid fuel FO into the air of high temperature compression.

The gas mode is a mode in which both the liquid fuel (FO) and the gaseous fuel (PG) are supplied to the combustion chamber (7). The gas mode may be referred to as a two-kind fuel mode. The gas mode is a mode in which the gaseous fuel PG supplied to the combustion chamber 7 at an arbitrary timing from the pilot flame generated by the small amount of liquid fuel FO supplied from the liquid fuel injection valve 9 to the combustion chamber 7, Is ignited and burned.

Details of the gas mode will now be described with reference to Figs. 3, 4 and 5. Fig. 3 shows a state in which the gaseous fuel PG is injected from the gaseous fuel valve 8 into the combustion chamber 7 in the gas mode and the liquid fuel FO is injected from the liquid fuel valve 9 into the combustion chamber 7 1 is a plan view schematically showing an example. 4 is a diagram schematically showing an example of a state in which the liquid fuel FO is burned in the gas mode. 5 is a plan view schematically showing an example of a state in which gaseous fuel PG is burned in the gas mode.

In the compression process, the air in the combustion chamber (7) is compressed. As shown in Fig. 3, in the combustion process, the gaseous fuel PG is injected into the combustion chamber 7 from the gaseous fuel injection valve 8. Further, a small amount of liquid fuel FO is injected into the combustion chamber 7 from the liquid fuel injection valve 9. The liquid fuel FO and the gaseous fuel PG are injected into the combustion chamber 7 almost at the same time when the piston 3 is disposed near the top dead center. In the gas mode, the main fuel is gaseous fuel (PG).

As shown in Fig. 3, the gaseous fuel injection valve 8 has a plurality of injection ports 8S for injecting gaseous fuel PG. The liquid fuel injection valve 9 has a plurality of ejection openings 9S for ejecting the liquid fuel FO. The gaseous fuel injection valve 8 injects the gaseous fuel PG toward the outside in the radial direction with respect to the axis of the gaseous fuel injection valve 8. [ The liquid fuel injection valve 9 injects the liquid fuel FO toward the outside in the radial direction with respect to the axis of the liquid fuel injection valve 9. [ Each of the gaseous fuel injection valve 8 and the liquid fuel injection valve 9 injects the gaseous fuel PG and the liquid fuel FO such that the gaseous fuel PG and the liquid fuel FO cross each other.

A small amount of liquid fuel FO injected from the liquid fuel injection valve 9 is spontaneously ignited to generate a pilot flame. The gaseous fuel injection valve 8 injects a high-pressure gaseous fuel PG. The high pressure gaseous fuel (PG) is at a pressure of 100 bar or more and 400 bar or less (for example, about 300 bar). In the gas mode, the gaseous fuel PG is ignited and burned based on the pilot flame generated by the small amount of liquid fuel FO injected into the combustion chamber 7 filled with the high-temperature, high-pressure air. Fig. 4 and Fig. 5 show an example of the state. In the gas mode, the gaseous fuel PG is burned as the main fuel.

Next, an example of the liquid fuel supply system 20 according to the present embodiment will be described. 6 is a cross-sectional view showing an example of the liquid fuel supply system 20 according to the present embodiment. 7, 8, and 9 are diagrams showing an example of the operation of the liquid fuel supply system 20 according to the present embodiment.

The liquid fuel supply system 20 supplies the liquid fuel FO to the combustion chamber 7 of the dual fuel engine 1. The liquid fuel supply system 20 is controlled by the control device 10. [ The liquid fuel supply system 20 has a liquid fuel injection valve 9 and a piston 25 for injecting liquid fuel FO into the combustion chamber 7 and a liquid fuel FO is supplied to the liquid fuel injection valve 9 And an accumulator 22 for controlling the supply of the liquid fuel pump 21 and the liquid fuel pump 21. The liquid fuel pump 21 is disposed on the upper surface of the housing of the accumulator 22. The number of liquid fuel pumps 21 is the same as the number of the combustion chambers 7 of the double dual engine 1. In this embodiment, the liquid fuel FO is supplied to the two liquid fuel injection valves 9 in one liquid fuel pump 21. 6 shows one liquid fuel injection valve 9 for the sake of convenience.

The liquid fuel injection valve 9 is a needle valve type in which the injection port 9S is opened when a predetermined pressure is applied. The liquid fuel injection valve 9 is connected to the liquid fuel pump 21 through the supply pipe 23 and supplies the liquid fuel FO supplied from the liquid fuel pump 21 to the combustion chamber 7 ).

The liquid fuel pump 21 has a cylinder 24 and a piston 25 at least a part of which is disposed inside the cylinder 24. The piston 25 has an upper surface 251 and a lower surface 252. The upper surface 251 of the piston 25 forms a fuel chamber (accommodation space) 26 in which the liquid fuel FO is received between the inner surfaces of the cylinder 24. The liquid fuel pump 21 further includes an inlet 27 for supplying the liquid fuel FO to the fuel chamber 26, an outlet 28 for discharging the excess liquid fuel FO from the fuel chamber 26, And a spring (29) arranged to contact at least a part of the piston (25).

The piston (25) is reciprocable within the cylinder (24). The piston 25 is movable between an upper position Pu and a lower position Pd. The upper position Pu is located at the uppermost position in the movable range of the piston 25. [ The lower end position Pd is located at the lowest position in the movable range of the piston 25. [

The piston 25 has a small diameter portion 25A and a large diameter portion 25B. The small-diameter portion 25A is disposed on the upper portion of the large-diameter portion 25B. The fuel chamber 26 is provided between the inner surface of the cylinder 24 and the upper surface 251 of the small diameter portion 25A. When the piston 25 moves upward, the volume of the fuel chamber 26 becomes small. When the piston 25 moves downward, the volume of the fuel chamber 26 becomes large.

The inlet 27 is connected to the fuel chamber 26 to supply the liquid fuel FO to the fuel chamber 26. The outlet 28 is connected to the fuel chamber 26 to discharge the surplus liquid fuel FO of the fuel chamber 26.

The spring 29 is disposed around the small-diameter portion 25A. The spring 29 is disposed between the large-diameter portion 25B and at least a part of the inner surface of the cylinder 24. The spring 29 applies a force (urging force) to the piston 25 so that the piston 25 moves downward.

The fuel chamber 26 is connected to the supply pipe 23 via the check valve 30. When the liquid fuel FO is supplied from the inlet 27 to the fuel chamber 26 and the piston 25 moves upward to reduce the volume of the fuel chamber 26, Is supplied to the liquid fuel injection valve 9 via the supply pipe 23. The excess liquid fuel FO in the fuel chamber 26 is discharged from the outlet 28.

The pressure accumulator 22 includes a high pressure passage 31 in which the piston 25 is filled with actuatable operating fluid (working liquid), a low pressure passage 32 in which the working oil is filled, Pressure tank 38 and a low-pressure tank 39 connected to the low-pressure passage 32 and containing operating oil.

The accumulator 22 further includes a main valve 33 capable of opening and closing the high pressure passage 31, a spill valve 34 capable of opening and closing the high pressure passage 31, A spring 43 arranged to be in contact with at least a part of the spill valve 34, a first passage (supply passage) 41 for supplying operating fluid to the main valve 33, A third passage 40 connected to the high pressure passage 31, a squeegee passageway 50 connectable to the first passage 41, a second passage 42 connected to the high pressure passage 31, And a pilot solenoid valve 35 for moving the main valve 33 and the spill valve 34. The pilot solenoid valve 35 has a main solenoid valve 36 and a sub solenoid valve 37 that operates separately from the main solenoid valve 36. The main solenoid valve 36 and the sub solenoid valve 37 are controlled by the control device 10. [

The high-pressure passage 31 is connected to the high-pressure tank 38. Pressure hydraulic fluid is supplied from the high-pressure tank 38 to the high-pressure passage 31. Pressure passage 31 is filled with high-pressure hydraulic fluid. The lower surface 252 of the piston 25 faces the high-pressure passage 31. The operating fluid of the high-pressure passage 31 is supplied to the lower surface 252 of the piston 25. [ The operating oil of the high-pressure passage 31 exerts a force on the lower surface 252 of the piston 25.

The low-pressure passage 32 is connected to each of the high-pressure passage 31 and the low-pressure tank 39. The low-pressure hydraulic fluid is supplied to the low-pressure passage 32 from the low-pressure tank 39. The low-pressure passage (32) is filled with the working oil which is lower in pressure than the working oil of the high-pressure passage (31). A check valve (45) is disposed in the low-pressure passage (32). The check valve 45 suppresses the working oil of the high-pressure passage 31 from flowing into the low-pressure passage 32.

The main valve 33 is capable of opening and closing the high-pressure passage 31. When the high pressure passage 31 is opened by the main valve 33, the high pressure tank 38 and the high pressure passage 31 under the piston 25 are connected. When the high-pressure passage 31 is closed by the main valve 33, the high-pressure tank 38 and the high-pressure passage 31 below the piston 25 are shut off. The main valve 33 is movable between an inner position and an outer position of the high-pressure passage 31. When the main valve 33 is disposed at an inner position of the high-pressure passage 31, the high-pressure passage 31 is closed. When the main valve 33 is disposed at an outer position of the high-pressure passage 31, the high-pressure passage 31 is opened. The spring 43 applies a force to the main valve 33 so that the main valve 33 moves from the inside position to the outside position of the high pressure passage 31. [ That is, the spring 43 exerts a force on the main valve 33 so that the main valve 33 retracts from the high-pressure passage 31 and opens the high-pressure passage 31.

The spill valve 34 is capable of opening and closing the high-pressure passage 31. When the high pressure passage 31 is opened by the spill valve 34, the low pressure tank 39 and the high pressure passage 31 under the piston 25 are connected. When the high pressure passage 31 is closed by the spill valve 34, the low pressure tank 39 and the high pressure passage 31 below the piston 25 are shut off. The spill valve 34 is movable between an inner position and an outer position of the high-pressure passage 31. When the spill valve 34 is disposed at an inner position of the high-pressure passage 31, the high-pressure passage 31 is closed. When the spill valve 34 is disposed at a position outside the high-pressure passage 31, the high-pressure passage 31 is opened. The spring 44 applies a force to the spill valve 34 so that the spill valve 34 moves from the inside position to the outside position of the high pressure passage 31. That is, the spring 44 exerts a force on the spill valve 34 so that the spill valve 34 retracts from the high-pressure passage 31 and opens the high-pressure passage 31.

In the following description, the inside position of the high-pressure passage 31 is referred to as a clogging position as appropriate. The main valve 33 is disposed at the closed position, so that the high-pressure passage 31 is closed by the main valve 33 (closed state). And the position of the outside of the high-pressure passage 31 is appropriately referred to as a retreat position. And the main valve 33 is disposed at the retreat position, so that the high-pressure passage 31 is in the open state (open state). In this embodiment, the open state includes a state other than the closed state. That is, in the present embodiment, the open state is a concept including not only a state in which the high-pressure passage 31 is fully opened but also a state in which the high-pressure passage 31 is slightly opened. In other words, the main valve 33 can adjust not only the opening and closing of the high-pressure flow path 31 but also the opening of the high-pressure flow path 31. The timing at which the high pressure passage 31 is opened by the main valve 33 and the timing at which the high pressure passage 31 is opened are controlled by the pilot solenoid valve 35 (the main solenoid valve 36 and the sub solenoid valve 37) do. The same is true of the spill valve 34.

The first passage (41) is capable of supplying operating oil to the main valve (33). The first passage (41) is connectable with the high-pressure passage (31). When the first passage 41 and the high-pressure passage 31 are connected, the hydraulic fluid is supplied to the first passage 41 from the high-pressure passage 31. The operating oil supplied from the high-pressure passage 31 to the main valve 33 flows through the first passage 41 while the first passage 41 and the high-pressure passage 31 are connected. The main valve 33 is moved by the pressure of the operating oil in the first passage 41. When the high-pressure hydraulic fluid from the high-pressure passage 31 is supplied to the first passage 41, the hydraulic fluid in the first passage 41 is supplied to the main valve 33 so that the main valve 33 is moved from the retracted position to the closed position I give strength. As a result, the high-pressure passage 31 is closed by the main valve 33.

The second passage (42) is capable of supplying operating oil to the spill valve (34). The second passage 42 is connectable with the high-pressure passage 31. When the second passage 42 and the high-pressure passage 31 are connected, the hydraulic fluid is supplied to the second passage 42 from the high-pressure passage 31. The operating oil supplied to the spill valve 34 in the high-pressure passage 31 flows through the second passage 42 while the second passage 42 and the high-pressure passage 31 are connected. The spill valve 34 is moved by the pressure of the operating oil of the second passage 42. When the high-pressure hydraulic fluid from the high-pressure passage 31 is supplied to the second passage 42, the operating oil of the second passage 42 is supplied to the spill valve 34 so as to move the spill valve 34 from the retracted position to the closed position I give strength. As a result, the high-pressure passage 31 is closed by the spill valve 34.

The third passage 40 is connected to the high-pressure passage 31 between the first passage 41 and the second passage 42. The third passage 40 has a main passage connected to the high-pressure passage 31 and a branch passage 40A and a branch passage 40B branched from the main passage.

The main solenoid valve 36 controls the operation of the main valve 33 and the spill valve 34. The main solenoid valve 36 is connected to the first passage 41 and the high pressure passage 31 so that the main valve 33 is disposed at an inner position of the high pressure passage 31, And the main valve (33) is disposed at an outer position of the high-pressure passage (31). The main solenoid valve 36 is connected to the second passage 42 and the high pressure passage 31 so that the spill valve 34 is disposed at an inner position of the high pressure passage 31, The passage 32 is connected to switch the spill valve 34 from one state to the other position in which the spill valve 34 is disposed at the outer side of the high-pressure passage 31.

In this embodiment, the main solenoid valve 36 is a so-called spool type. The main solenoid valve 36 has a cylindrical spool valve 46 and a solenoid 47 and a solenoid 48 for moving the spool valve 46 in the axial direction. The solenoid 47 is disposed above the solenoid 48. When the solenoid 47 on the upper side is turned ON, the spool valve 46 is raised by the action (magnetic force) of the solenoid 47 and is disposed at the first position P1 as shown in Fig. When the lower solenoid 48 is turned ON, the spool valve 46 is lowered by the action (magnetic force) of the solenoid 48 and is disposed at the second position P2 as shown in Fig.

That is, the spool valve 46 is movable between the first position P1 and the second position P2 by the action of the solenoid 47 and the solenoid 48. The first position Pl is located at the uppermost position in the movable range of the spool valve 46. The second position P2 is located at the lowest position in the movable range of the spool valve 46.

The spool valve 46 has a groove 46A and a groove 46B. The groove 46A and the groove 46B are formed in the circumferential direction on the outer surface of the spool valve 46. [

The accumulator 22 has a squeeze passage 50 into which at least a part of the working oil in the first passage 41 can flow. The stylus tube (50) is connected to the low pressure passage (32). At least a part of the working fluid in the first passage (41) flows to the squeeze passage (50), so that the pressure of the working oil in the first passage (41) drops. The spigot conduit 50 includes a quick-sill passage 50A for rapidly lowering the pressure of the hydraulic fluid in the first passage 41 and a slow-speed pen case 50A for slowly reducing the pressure of the hydraulic fluid in the first passage 41. [ (50B). The slow pencil case passage 50B is narrower than the quick-turn pencil case passage 50A. That is, the passage area of the slow passage (50B) is smaller than the passage area of the quick passage (50A). In the present embodiment, the orifice 53 is arranged in the slow pencil case passage 50B. The orifice 53 reduces the size (passage area) of the slow pencil case passage 50B.

The sub solenoid valve 37 is disposed in the quick-turn pencil passageway 50A. The sub solenoid valve 37 adjusts the flow rate of the operating oil flowing out of the first passage 41 and controls the flow rate of the main valve 33 when the main valve 33 moves from the inside position to the outside position of the high pressure passage 31, The speed of movement of the motor is adjusted. The sub solenoid valve 37 is operated in a state in which the hydraulic oil from the first passage 41 flows through the quick-sis pen cylinder passage 50A and the state in which the hydraulic oil from the first passage 41 does not flow through the quick- The moving speed of the main valve 33 is adjusted by switching from one to the other.

7, when the solenoid 47 is turned ON and the spool valve 46 is raised to the first position P1, the first passage 41 is communicated with the spool valve 50 . In the state shown in Fig. 7, the first passage 41 is connected to the low-pressure passage 32 via the groove 46A and the scroll tube passage 50. [ The first passage 41 and the low pressure passage 32 are connected to each other so that at least a portion of the working oil in the first passage 41 flows into the low pressure passage 32 through the passage 60. As a result, the pressure of the working oil in the first passage 41 is lowered, and the pressure of the working oil acting on the main valve 31 is lowered. When the pressure of the working oil in the first passage 41 drops, the main valve 33 moves from the closed position to the retreat position by the force of the spring 43. As a result, the high-pressure passage 31 is opened.

The branch passage 40A of the third passage 40 is closed by the outer surface of the spool valve 46 in the state shown in Fig. While the branch passage 40B of the third passage 40 is connected to the second passage 42 via the groove 46B. That is, the high-pressure passage 31 and the second passage 42 are connected via the branch passage 40B and the groove 46B. As a result, the pressure of the working oil in the second passage 42 increases and the pressure of the operating oil acting on the spill valve 34 increases. When the pressure of the working oil in the second passage 42 increases, the spill valve 34 moves to the closed position by the pressure of the operating oil. As a result, the high-pressure passage 31 is closed by the spill valve 34.

When the main valve 33 is disposed at the retracted position and the spill valve 34 is disposed at the closed position, the high-pressure hydraulic fluid in the high-pressure passage 31 applies force to the lower surface 252 of the piston 25. [ The piston 25 moves (rises) toward the upper position Pu by the force of the high-pressure hydraulic fluid in the high-pressure passage 31. [ The piston 25 is moved by the force of the operating oil to reduce the volume of the fuel chamber 26 and the liquid fuel FO of the fuel chamber 26 is compressed so that the liquid fuel FO of the fuel chamber 26 And the pressure of the working oil of the supply pipe 23 and the pressure of the working oil of the liquid fuel injection valve 9 are increased. The injection port 9S of the liquid fuel injection valve 9 is opened and the liquid fuel FO is injected from the injection port 9S into the combustion chamber of the dual fuel engine 9, (7).

8, when the solenoid 48 is turned ON and the spool valve 46 is lowered and disposed at the second position P2, the first passage 41 is communicated with the third passage 40 And is connected to the high-pressure passage 31 via the groove 46A and the third passage 40. The high- On the other hand, the branch passage 40B of the third passage 40 is closed by the outer surface of the spool valve 46. The first passage 41 and the high pressure passage 31 are connected to each other so that at least a portion of the high pressure hydraulic fluid in the high pressure passage 31 flows into the first passage 41 via the third passage 40. As a result, the pressure of the operating oil in the first passage 41 increases and the pressure of the operating oil acting on the main valve 33 increases. When the pressure of the working oil in the first passage 41 increases, the main valve 33 moves from the retracted position to the closed position by the pressure of the working oil. As a result, the high-pressure passage 31 is closed by the main valve 33.

In the state shown in Fig. 8, the second passage 42 is connected to the low-pressure passage 32 via the groove 46B. By connecting the second passage 42 and the low-pressure passage 32, at least a part of the working oil in the second passage 42 flows into the low-pressure passage 32. As a result, the hydraulic pressure of the hydraulic oil in the second passage 42 decreases, and the pressure of the hydraulic oil acting on the spill valve 34 decreases. When the pressure of the working oil in the second passage 42 decreases, the spill valve 34 moves to the retreat position by the force of the spring 44. As a result, the high-pressure passage 31 is opened.

Further, since the operating fluid of the high-pressure passage 31 does not flow into the low-pressure passage 32 by the check valve 45, the pressures of the low-pressure passage 32 and the second passage 42 are maintained.

When the main valve 33 is disposed at the closed position and the spill valve 34 is disposed at the retracted position, the pressure of the operating oil on the lower surface 252 of the piston 25 decreases. When the pressure of the operating oil acting on the piston 25 decreases, the piston 25 moves (descends) under the lower end position Pd by the action of the spring 29.

Thus, in the present embodiment, the main valve 33 moves between the retracted position and the closed position on the basis of the pressure of the operating oil in the first passage 41. [ The main valve 33 moves between the retracted position and the closed position to open / close the high pressure passage 31.

The main solenoid valve 36 is connected to the main valve 33 via the first passage 41 so that the high pressure passage 31 is changed from the closed state to the open state by the main valve 33 The pressure of the supplied hydraulic fluid is switched.

The main solenoid valve 36 connects the first passage 41 and the spit pipe passage 50 (low pressure passage 32) by arranging the spool valve 46 in the first position P1. As a result, the pressure of the working oil in the first passage 41 becomes equal to the pressure Pr1 of the working oil in the low-pressure passage 32. By connecting the first passage 41 and the squeegee passage 50, the main valve 33 is disposed at the retreat position and the high-pressure passage 31 is opened.

The main solenoid valve 36 connects the first passage 41 and the high pressure passage 31 by arranging the spool valve 46 at the second position P2. As a result, the pressure of the hydraulic fluid in the first passage 41 becomes equal to the pressure Pr2 of the hydraulic fluid in the high-pressure passage 31. By connecting the first passage 41 and the high-pressure passage 31, the main valve 33 is disposed at the closed position and the high-pressure passage 31 is closed.

Thus, the main solenoid valve 36 can switch the pressure of the working oil in the first passage 41 from one of the pressure Pr1 and the pressure Pr2 to the other. Similarly, the main solenoid valve 36 can switch the pressure of the working oil in the second passage 42 from one of the pressure Pr2 and the pressure Pr1 to the other. As a result, the high-pressure passage 31 changes from one of the open state in which the operating oil of the pressure Pr2 is applied to the piston 25 and the closed state in which the operating oil of the pressure Pr1 is applied.

In the following description, the state in which the main valve 33 is disposed at the retracted position by the main solenoid valve 36 is referred to as an open state of the main solenoid valve 36 as appropriate. The state in which the main valve 33 is closed by the main solenoid valve 36 is referred to as a closed state of the main solenoid valve 36 as appropriate. The operation of moving the main valve 33 to the retreat position by the main solenoid valve 36 is referred to as an opening operation of the main solenoid valve 36 as appropriate. The operation of moving the main valve 33 to the retreat position by the main solenoid valve 36 is referred to as a close operation of the main solenoid valve 36 as appropriate.

The opening operation of the main solenoid valve 36 is an operation for bringing the high-pressure passage 31 into an open state, and is an operation for moving the spool valve 46 to the first position P1. The opening operation of the main solenoid valve 36 also includes an operation of moving the spool valve 34 to the closed position.

The closing operation of the main solenoid valve 36 is an operation for bringing the high-pressure passage 31 into the closed state, and is an operation for moving the spool valve 46 to the second position P2. The closing operation of the main solenoid valve 36 includes an operation of moving the spool valve 34 to the retreat position.

In this embodiment, by repeating the opening and closing operations of the main solenoid valve 36, the pressure of the working oil acting on the lower surface 252 of the piston 25 changes from one of the pressure Pr2 and the pressure Pr1 to the other. The pressure Pr2 is greater than the force of the spring 29. [ The pressure Pr1 is smaller than the force of the spring 29. [ The pressure of the working oil changes from one of the pressure Pr2 and the pressure Pr1 to the other so that the piston 25 moves between the upper end position Pu and the lower end position Pd to change the volume of the fuel chamber 26. [ As a result, the liquid fuel FO is injected from the liquid fuel injection valve 9.

In this embodiment, when the main solenoid valve 36 is opened, injection of the liquid fuel FO from the liquid fuel injection valve 9 is started. When the main solenoid valve 36 is closed, injection of the liquid fuel FO from the liquid fuel injection valve 9 is stopped.

Next, the sub solenoid valve 37 will be described. The sub solenoid valve 37 adjusts the flow rate per unit time of the hydraulic oil flowing out from the first passage 41 to the low pressure passage 32 via the spill pipe passage 50 and the main valve 33 is retracted from the closed position The moving speed of the main valve 33 is adjusted. The pressure change amount (pressure change rate) of the operating oil per unit time of the first passage 41 is adjusted by adjusting the flow rate per unit time of the operating oil flowing out of the first passage 41. The moving speed of the main valve 33 when the high pressure passage 31 is changed from the closed state to the open state is adjusted by adjusting the pressure change rate of the working oil in the first passage 41. [ That is, the moving speed of the main valve 33 when the main valve 33 is moved from the closed position to the open position is adjusted by adjusting the pressure change speed of the working oil in the first passage 41.

The sub solenoid valve 37 is disposed in the quick-turn pencil passageway 50A. In the present embodiment, the sub solenoid valve 37 is a so-called spool type. The sub solenoid valve 37 has a cylindrical spool valve 51 and a solenoid 52 for moving the spool valve 51 in the axial direction.

The spool valve 51 has a groove 51A. The groove 51A is formed in the circumferential direction on the outer surface of the spool valve 51. [

When the solenoid 52 is turned ON, the spool valve 51 rises due to the action (magnetic force) of the solenoid 52 and is disposed at the third position P3 as shown in Figs. When the solenoid 52 is turned OFF, the spool valve 51 is lowered by the action of gravity and is disposed at the fourth position P4 as shown in Fig.

7 and 8, when the solenoid 52 is turned ON and the spool valve 51 is moved upward to be disposed at the third position P3, the quick-sill pen case passage 50A is guided through the groove 51A to the low pressure And is connected to the passage 32.

The solenoid 52 is turned OFF and the spool valve 51 is lowered to the fourth position P4 as shown in Fig. 9, the quick-turn solenoid passage 50A is closed by the outer surface of the spool valve 51 .

The spool valve 51 of the sub solenoid valve 37 is disposed at the third position P3 and the quick solenoid valve 50A and the low pressure passage 32 are connected, When the spool valve 46 is moved from the second position P2 to the first position P1 at least a part of the working fluid in the first passage 41 of the pressure Pr2 flows through the groove 46A, the quick- Flows through the groove 51A toward the low-pressure passage 32 at a high speed. At least a part of the operating fluid of the first passage 41 flows toward the low-pressure passage 32 through the slow-force pencil passage 50B. As a result, the pressure of the working oil in the first passage 41 rapidly drops from the pressure Pr2 to the pressure Pr1. As a result, the main valve 33 disposed at the closed position moves from the closed position to the retreat position at the high speed (second speed) V2.

When the main valve 33 moves from the closed position to the retracted position on the highway, the high-pressure passage 31 rapidly changes from the closed state to the open state. Accordingly, the pressure of the hydraulic fluid in the high-pressure passage 31 acting on the lower surface 252 of the piston 25 increases sharply. As a result, the piston 25 rises rapidly. The volume of the fuel chamber 26 is sharply reduced and the pressure of the liquid fuel FO of the fuel chamber 26 and the pressure of the liquid fuel FO of the liquid fuel injection valve 9 are rapidly increased, The velocity of the liquid fuel FO injected from the valve 9 becomes high.

When the spool valve 51 of the sub solenoid valve 37 is disposed at the fourth position P4 and the spool valve 46 of the main solenoid valve 36 is closed by the quick solenoid valve 50A, The operating oil of the first passage 41 of the pressure Pr2 is guided to the low pressure passage 32 via the groove 46A and the slow passage case passage 50B in the case of moving from the second position P2 to the first position P1 It flows at low speed. The operating oil of the first passage 41 flows slowly toward the low-pressure passage 32 by the flow resistance of the orifice 53 because the orifice 53 for reducing the passage area is provided in the slow- The operating oil from the first passage 41 does not flow through the quick-sill pen case passage 50A in a state in which the spool valve 51 of the sub solenoid valve 37 is disposed at the fourth position P4. As a result, the pressure of the working oil in the first passage 41 gradually decreases from the pressure Pr2 to the pressure Pr1. As a result, the main valve 33 disposed at the closed position moves from the closed position to the retracted position at a low speed (first speed) V1. The second speed V2 is higher than the first speed V1 (high speed).

When the main valve 33 moves from the closed position to the retreat position at a low speed, the high-pressure passage 31 gradually changes from the closed state to the open state. Therefore, the pressure of the hydraulic fluid in the high-pressure passage 31 acting on the lower surface 252 of the piston 25 is gradually increased. As a result, the piston 25 rises gently. The volume of the fuel chamber 26 gradually decreases and the pressure of the liquid fuel FO of the fuel chamber 26 and the pressure of the liquid fuel FO of the liquid fuel injection valve 9 gradually increase, The speed of the liquid fuel FO injected from the fuel injection valve 9 is lowered.

Thus, in this embodiment, the sub solenoid valve 37 adjusts the flow rate per unit time of the operating oil flowing out of the first passage 41 and changes the pressure variation rate (pressure variation rate) of the operating oil per unit time acting on the main valve 33, . As a result, the moving speed of the main valve 33 when the main valve 33 is moved from the closed position to the retreat position can be adjusted to at least one of the first speed V1 and the second speed V2. The ascending speed of the piston 25 is adjusted by adjusting the moving speed of the main valve 33. Thereby, the injection speed of the liquid fuel FO injected from the liquid fuel injection valve 9 is adjusted.

In the following description, the quick seal pencil case 50A is opened and the operating oil of the first passage 41 is supplied to the low pressure passage 32 through both the quick-sill pen case passage 50A and the slow- And the flowing state is appropriately referred to as the open state of the sub solenoid valve 37. The quick seal pencil case 50A is closed so that the operating oil of the first passage 41 does not flow through the quick-squeeze path 50A but flows into the low-pressure path 32 via the slow- Solenoid valve 37 is properly closed. The operation of opening the quick-turn pencil case 50A is referred to as an opening operation of the sub solenoid valve 37 as appropriate. The operation of closing the quick-turn pencil case 50A is referred to as a close operation of the sub solenoid valve 37 as appropriate.

The open state of the sub solenoid valve 37 includes a state in which the main valve 33 at the closed position moves to the retreated position at the second speed V2. The closed state of the sub solenoid valve 37 includes a state in which the main valve 33 at the closed position moves toward the retreat position to the first speed V1 which is lower than the second speed V2.

10 is a diagram showing an example of the sub solenoid valve 37 according to the present embodiment. As shown in Fig. 10, the solenoid 52 of the sub solenoid valve 37 has an inner solenoid 52A and an outer solenoid 52B disposed around the inner solenoid 52A. The outer solenoid 52B generates a larger force (magnetic force) than the inner solenoid 52A in the state where the same voltage is applied to each of the inner solenoid 52A and the outer solenoid 52B. In the present embodiment, the force generated by the outer solenoid 52B is about twice that generated by the inner solenoid 52A. For example, it is possible to make the forces generated by the inner solenoid 52A and the outer solenoid 52B respectively different from each other by making the number of turns of the coils different.

The sub solenoid valve 37 includes a power source 54 for applying a voltage to the inner solenoid 52A, a switch for switching whether or not to apply a voltage to the inner solenoid 52A in the power source 54, And a switch 57 for switching whether or not to apply a voltage to the outer solenoid 52B in the power supply 56. [ As a result, individual power is given to each of the inner solenoid 52A and the outer solenoid 52B.

In this embodiment, the controller 10 operates the switch 55 and the switch 57 to selectively apply a voltage to each of the inner solenoid 52A and the outer solenoid 52B. Thereby, the control apparatus 10 can change the force (magnetic force) generated by the solenoid 52 in various stages.

For example, when voltage is applied only to the inner solenoid 52A, the solenoid 52 generates the force F1. When a voltage is applied only to the outer solenoid 52B, the solenoid 52 generates a force F2 larger than the force F1. When a voltage is applied to both the inner solenoid 52A and the outer solenoid 52B, the solenoid 52 generates a force F3 that is greater than the force F1 and the force F2.

In this embodiment, by changing the force of the solenoid 52 of the sub solenoid valve 37, the moving speed of the main valve 33 can be finely adjusted, and the ascending speed of the piston 25 can be finely adjusted. Therefore, the injection speed of the liquid fuel FO from the liquid fuel injection valve 9 can be finely adjusted.

That is, when the force of the solenoid 52 of the sub solenoid valve 37 is weakened, the moving speed of the spool valve 51 is lowered, and the time until the sub solenoid valve 37 is opened becomes longer. Therefore, the moving speed of the main valve 33 is lowered. The injection speed of the liquid fuel FO injected from the liquid fuel injection valve 9 is lowered. On the other hand, if the force of the solenoid 52 is increased, the moving speed of the spool valve 51 becomes higher and the injection speed of the liquid fuel FO injected from the liquid fuel injection valve 9 becomes higher.

Next, an example of the operation of the liquid fuel supply system 20 according to the present embodiment will be described. The control device 10 controls the main solenoid valve 36 and the sub solenoid valve 37 to control the pressure of the liquid fuel FO injected into the combustion chamber 7 from the liquid fuel injection valve 9 Injection pressure) can be adjusted. The injection pressure of the liquid fuel FO is controlled such that the injection of the liquid fuel FO from the liquid fuel injection valve 9 starts when the liquid fuel FO is not injected from the liquid fuel injection valve 9 And the pressure of the liquid fuel FO (injection pressure at the start). The starting injection pressure is a change amount of the pressure of the liquid fuel FO injected from the liquid fuel injection valve 9 when the injection of the liquid fuel FO into the combustion chamber 7 is started in the liquid fuel injection valve 9 (An increase in pressure per unit time). The control device 10 can adjust the injection pressure (increase amount of the pressure per unit time) of the liquid fuel FO including the injection pressure at the start by adjusting the moving speed of the main valve 33. [

11 is a view for explaining an example of the operation of the main solenoid valve 36 and the sub solenoid valve 37 in the diesel mode. In the graph shown in Fig. 11, the horizontal axis represents time. The vertical axis indicates the pressure of the liquid fuel FO according to the liquid fuel injection valve 9 (or the fuel chamber 26). In Fig. 11, the state (open state or closed state) of the main solenoid valve 36 and the sub solenoid valve 37 corresponding to the time is described.

At time T ₀ , each of the main solenoid valve 36 and the sub solenoid valve 37 is in the closed state. Therefore, the time T ₀ the liquid fuel (FO) from the liquid fuel injection valve 9 is not in the injection.

The control device 10 opens the main solenoid valve 36 at the time point Ta. At time Ta, the sub solenoid valve 37 is in a closed state. When the main solenoid valve 36 is opened, the main valve 33 at the closed position at the time point Ta starts to move toward the retreat position. At the time point Ta, the injection of the liquid fuel FO from the liquid fuel injection valve 9 is started.

The control device 10 keeps the sub solenoid valve 37 open while maintaining the open state of the main solenoid valve 36 at the next time point Tb of the point of time Ta. That is, both the main solenoid valve 36 and the sub solenoid valve 37 are open at the time point Tb. At the time point Tb, the main valve 33 does not reach the retreat position. At the time point Tb, the main valve 33 is disposed at an intermediate position between the closed position and the retracted position.

The control device 10 closes both the main solenoid valve 36 and the sub solenoid valve 37 at the next time point Tc of the time point Tb. Therefore, the injection of the liquid fuel FO from the liquid fuel injection valve 9 is stopped at the time point Tc. At the time point Tc, the main valve 33 is disposed at the retreat position. At the time point Tc, the main solenoid valve 36 is closed and the main valve 33 is returned to the closed position.

In the period from the time point Ta to the time point Tb, since the main solenoid valve 36 is open and the sub solenoid valve 37 is closed, the main valve 33 is moved from the closed position to the intermediate position to the first speed V1 do. The main valve 33 moves to the low speed (first speed) V1 during the period from the time point Ta to the time point Tb and the pressure of the operating oil that acts on the lower surface 252 of the piston 25 gradually rises, The pressure of the fuel FO gradually rises.

Since the main solenoid valve 36 is opened and the sub solenoid valve 37 is also open during the period from the time point Tb to the time point Tc, the main valve 33 is moved from the intermediate position to the retreat position to the second speed V2 do. The main valve 33 moves to the high speed (second speed) V2 during the period from the time point Tb to the time point Tc and the pressure of the working oil acting on the lower surface 252 of the piston 25 abruptly rises, The pressure of the fuel FO rises sharply.

In the present embodiment, in the diesel mode, the main valve 33 is moved to the first speed V1 in the past (from the time point Ta to the time point Tb) in the moving period from the closing position to the retreat position, (The period from the time point Tb to the time point Tc), the second speed V2 is higher than the first speed V1. The liquid fuel injected from the liquid fuel injection valve 9 (in the period from the point of time Ta to the point of time Tb) in the injection period (the period from the point of time Ta to the point of time Tc) in which the liquid fuel FO is injected The injection amount (injection rate) of the fuel injection amount FO can be reduced and the combustion temperature can be reduced. Therefore, for example, the generation of NOx can be suppressed. The liquid fuel FO required for combustion in the diesel mode can be supplied to the combustion chamber 7 by increasing the injection rate in the latter period of the injection period (the period from the time point Tb to the time point Tc).

Next, an example of the operation of the liquid fuel supply system 20 according to the gas mode will be described. 12 is a view for explaining an example of the operation of the main solenoid valve 36 and the sub solenoid valve 37 according to the gas mode. In the graph shown in Fig. 12, the horizontal axis represents time. The vertical axis indicates the pressure of the liquid fuel FO according to the liquid fuel injection valve 9 (or the fuel chamber 26). 12 shows the state (open state or closed state) of the main solenoid valve 36 and the sub solenoid valve 37 corresponding to the time. 12, the line L1 shows an example of the operation of the main solenoid valve 36 and the sub solenoid valve 37 according to the present example, and the line L2 shows an example of the operation of the main solenoid valve 36 and a sub solenoid valve 37 as shown in Fig.

At time T ₀ , each of the main solenoid valve 36 and the sub solenoid valve 37 is in the closed state. Therefore, the time T ₀ the liquid fuel (FO) from the liquid fuel injection valve 9 is not in the injection.

The control device 10 simultaneously opens the main solenoid valve 36 and the sub solenoid valve 37 at the time point Ta. When the main solenoid valve 36 is opened, the main valve 33 at the closed position at the time point Ta starts to move toward the retreat position. At the time point Ta, the injection of the liquid fuel FO from the liquid fuel injection valve 9 is started.

The control device 10 closes both the main solenoid valve 36 and the sub solenoid valve 37 at the next time point T1 of the point of time Ta. Therefore, the injection of the liquid fuel FO from the liquid fuel injection valve 9 is stopped at the time point T1. The period from the point of time Ta to the point of time T1 is shorter than the period of time from the point of time Ta to the point of time Tb described with reference to Fig. At the time point T1, the main valve 33 does not reach the retreat position. At the time point T1, the main valve 33 is disposed at an intermediate position between the closed position and the retracted position. At the time point Tc, the main solenoid valve 36 is closed and the main valve 33 returns from the intermediate position to the closed position.

Both the main solenoid valve 36 and the sub solenoid valve 37 are opened at the time point Ta so that the main valve 33 is moved from the closed position to the retreat position at a second speed V2 higher than the first speed V1 ). In the present embodiment, the main valve 33 moves from the closed position to the intermediate position in the high-speed (second speed) V2 in the period from the time point Ta to the time point T1. Therefore, the pressure of the working oil acting on the lower surface 252 of the piston 25 abruptly rises and the pressure of the liquid fuel FO rises sharply in the period from the time point Ta to the time point T1 of the gas mode.

In Fig. 12, each of the area AR1 and the area AR2 corresponds to the supply amount of the liquid fuel FO. The area of the area AR1 is equal to the area of the area AR2. As shown in Fig. 12, in this example, it can be seen that the pressure of the liquid fuel FO is high and a predetermined amount of the liquid fuel FO can be supplied in a short time.

According to the present embodiment, in the case where a small amount of the liquid fuel FO is supplied to the combustion chamber 7 in the gas mode, the control device 10 rapidly increases the pressure of the liquid fuel FO of the liquid fuel injection valve 9 So that the liquid fuel FO is jetted at a high speed from a jetting port 9S of the liquid fuel injection valve 9 in a short time. Therefore, it is possible to stably supply a small amount of liquid fuel (FO) while suppressing adhesion of foreign matter to the injection port 9S.

That is, in the present embodiment, the main solenoid valve 36 is changed from the closed state to the open state, and the liquid fuel injection valve 9 is switched to the open state in the state where the liquid fuel FO is not injected from the liquid fuel injection valve 9 The fuel FO is changed to a state in which the fuel FO is injected. The pressure of the liquid fuel FO at the time when the injection of the liquid fuel FO from the liquid fuel injection valve 9 is started from the state where the liquid fuel FO is not injected The gas mode is higher. In other words, when the main solenoid valve 36 is changed from the closed state to the open state and the injection of the liquid fuel FO into the combustion chamber 7 is started in the liquid fuel injection valve 9, The amount of change in the pressure of the liquid fuel FO injected from the diesel mode is larger in the gas mode than in the diesel mode.

13 (A) and 13 (B) are diagrams showing an example of a control method of the sub solenoid valve 37 according to the diesel mode. 13 (A) shows the relationship between the Fuel Index FI, which is an index of the amount of fuel injected into the combustion chamber 7, and the load of the dual fuel engine 1. 13B shows a difference between the time when the main solenoid valve 36 is opened and the time when the sub solenoid valve 37 is opened (the delay time until the sub solenoid valve 37 is opened) And the Fuel Index FIO, which is an index of the injection amount of the liquid fuel FO injected into the combustion chamber 7. The fuel index FI is a Fuel Index relating to all the fuels including both the gaseous fuel PG and the liquid fuel FO. The Fuel Index (FIO) is the Fuel Index for the liquid fuel (PO).

As shown in Fig. 13 (A), in the diesel mode, the fuel index FI coincides with the Fuel index FIO, which is an index of the injection amount of the liquid fuel FO.

The control device 10 may increase the delay time when the injection amount of the liquid fuel FO is reduced and the delay time when the injection amount of the liquid fuel FO is increased as shown in Fig. 13 (B). That is, when the injection amount of the liquid fuel FO is reduced in the diesel mode, the controller 10 reduces the difference between the point of time Ta and the point of time Tb described with reference to FIG. 11 and increases the injection amount of the liquid fuel FO The difference between the point of time Ta and the point of time Tb may be increased.

14A and 14B are diagrams showing an example of a control method of the sub solenoid valve 37 according to the gas mode. Fig. 14 (A) shows the relationship between the Fuel Index FI and the load. 14B shows the relationship between the delay time until the sub solenoid valve 37 is opened and the Fuel Index FIO which is an index of the injection amount of the liquid fuel FO injected into the combustion chamber 7. As shown in Fig.

14 (A), in the gas mode, the fuel index FI is a Fuel Index (FIG) which is an index of the injection amount of the gaseous fuel PG and the Fuel Index FIO, which is an index of the injection amount of the liquid fuel FO, Are equal. The Fuel Index (FIO) is the Fuel Index for the gaseous fuel (PG).

The controller 10 may increase the delay time when the injection amount of the liquid fuel FO is reduced and the delay time when the injection amount of the liquid fuel FO is increased as shown in Fig. 14 (B). In the present embodiment, the liquid fuel FO is injected into the combustion chamber 7 so that the value of the Fuel Index FIO is 10 in the gas mode. As shown in Fig. 14 (B), the delay time (the difference between the point of time Ta and the point of time T1 described with reference to Fig. 12) when the FIO value is 10 is zero.

In the embodiment described with reference to Fig. 12, the main solenoid valve 36 and the sub solenoid valve 37 are simultaneously opened in the gas mode. 14B, when the value of FIO in the gas mode is large (when the injection amount of the liquid fuel FO to the combustion chamber 7 is increased), the main solenoid valve 36 is opened The sub solenoid valve 37 may be opened. It may be determined whether or not the main solenoid valve 36 and the sub solenoid valve 37 are simultaneously opened based on the injection amount of the liquid fuel FO to the combustion chamber 7 in the gas mode, 36 and the timing at which the sub solenoid valve 37 is opened may be different from each other and the timing at which the main solenoid valve 36 is opened and the sub solenoid valve 37 is opened (Delay time) between the time points at which the time points are set.

As described above, according to the present embodiment, when the injection of the liquid fuel FO into the combustion chamber 7 in the liquid fuel injection valve 9 is started, the pressure of the liquid fuel FO according to the gas mode It is possible to stably supply a small amount of the liquid fuel FO while suppressing adhesion of the foreign matter to the injection port 9S by adjusting the pressure of the liquid fuel FO to be higher than the pressure of the liquid fuel FO according to the diesel mode. That is, in the case where a small amount of liquid fuel FO is injected into the combustion chamber 7 in the gas mode, the pressure of the liquid fuel FO of the liquid fuel injection valve 9 is rapidly increased, It is possible to stably supply a small amount of liquid fuel FO while suppressing the adhesion of foreign matter to the injection port 9S.

Further, according to the present embodiment, since the injection amount (injection ratio) of the liquid fuel FO injected from the liquid fuel injection valve 9 is reduced in the electricity in the injection period in which the liquid fuel FO is injected in the diesel mode, Temperature can be reduced. Therefore, for example, the generation of NOx can be suppressed. Further, since the injection rate is increased at a later stage of the injection period, the liquid fuel FO required for combustion in the diesel mode can be supplied to the combustion chamber 7. [

1 Dual Fuel Engine
7 combustion chamber
9 Liquid Fuel Injection Valve
20 Liquid Fuel Supply System
24 cylinders
25 piston
26 Combustion chamber (accommodation space)
31 High pressure passage
33 main valve
36 Main Solenoid Valve
37 Sub Solenoid Valve
251 Top surface
252
FO liquid fuel
PG gaseous fuel

Claims (5)

1. A liquid fuel supply system for supplying a liquid fuel to a combustion chamber of a dual fuel engine,
An injection valve for injecting the liquid fuel into the combustion chamber,
And a control device capable of adjusting the injection pressure of the liquid fuel injected into the combustion chamber in the injection valve,
Wherein the injection pressure comprises an injection pressure at the start of the liquid fuel when injection of the liquid fuel from the injection valve is started,
Wherein the control device controls the start-time injection pressure according to the gas mode in which both the liquid fuel and the gaseous fuel are supplied to the combustion chamber, the start-time injection pressure corresponding to the initiation time according to the diesel mode in which the liquid fuel is supplied to the combustion chamber, The injection pressure is adjusted to be higher than the injection pressure. The method according to claim 1,
A pump capable of supplying the liquid fuel to the injection valve with a piston,
A high pressure passage in which the piston is filled with actuatable working liquid,
A main valve which is movable between an inside position and an outside position of the high pressure passage and which is disposed at the inside position and closes the high pressure passage and opens the high pressure passage at the outside position,
A supply passage that is connectable with the high-pressure passage and through which the working liquid supplied to the main valve flows in the high-pressure passage in a state of being connected to the high-
A spill passage connectable with the supply passage,
The supply passage and the high-pressure passage are connected to each other so that the main valve is disposed at the inner position, and the state in which the main valve is disposed at the outer position by connecting the supply passage and the spill passage is switched to the other A main electromagnetic valve,
And a sub-solenoid valve disposed in the spill passage and capable of adjusting a flow rate of the working liquid flowing out of the supply passage so as to adjust a moving speed of the main valve when the main valve moves from the inside position toward the outside position and,
Wherein the control device controls the main solenoid valve and the sub solenoid valve and adjusts the injection pressure so that in the diesel mode the main valve moves at the first position at the inner position, And controls the main solenoid valve and the sub solenoid valve to move at the inward position at a second speed higher than the first speed to adjust the start-time injection pressure according to each of the diesel mode and the gas mode, Fuel supply system. 3. The method of claim 2,
Wherein the spill passage includes a quick spill passage and a slow spill passage narrower than the quick spill passage,
Wherein the sub solenoid valve switches from one state to another state in which the working liquid from the supply passage flows through the quick spill passage and the working liquid from the supply passage does not flow through the quick spill passage, system. The method according to claim 2 or 3,
And the sub solenoid valve includes a solenoid. The method according to claim 2 or 3,
Wherein the main valve in the diesel mode moves at the first speed in the electricity of the moving period from the inside position to the outside position and moves at a speed higher than the first speed in the latter period of the moving period, system.

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