JP6772956B2 - Fuel injection system for dual fuel diesel engine - Google Patents

Description

The present invention relates to a fuel injection device for a dual fuel diesel engine.

In recent years, as shown in Patent Document 1, a dual fuel diesel engine has been developed in which a gaseous fuel such as compressed natural gas is used as a main fuel and a liquid fuel such as light oil is used as an ignition auxiliary fuel. In a dual fuel diesel engine, gaseous fuel is mixed with intake air and compressed, and a small amount of liquid fuel is injected into the combustion chamber where the temperature and pressure are high near the top dead point to self-ignite the liquid fuel, and this flame is gas. By spreading the fire to the fuel, the gas fuel with low self-ignition is burned. Therefore, in the dual fuel diesel engine, the combustion characteristics of the gaseous fuel having low self-ignition property are supplemented by the ignition assistance by the liquid fuel having high self-ignition property.

JP-A-2002-327633

By the way, in a dual fuel diesel engine using gaseous fuel as the main fuel, the combustion temperature is higher than that of a normal diesel engine using liquid fuel as the main fuel, and it is considerably higher than the time when the piston reaches the top dead point. Since a small amount of liquid fuel is injected into the combustion chamber at the previous timing, the fuel injection valve of the liquid fuel arranged in the combustion chamber is exposed to high-temperature combustion gas without injection when the main fuel is burned. For this reason, the dual fuel diesel engine has a problem that deposits are likely to be accumulated in the fuel injection hole of the fuel injection valve and its surroundings as compared with a normal diesel engine.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel injection device for a dual fuel diesel engine that suppresses the accumulation of deposits in the fuel injection hole of a fuel injection valve and its surroundings. is there.

In order to solve the above problems, the present invention is installed in the combustion chamber of a dual fuel diesel engine using gaseous fuel as the main fuel and liquid fuel as the auxiliary fuel, and an auxiliary fuel injection valve capable of injecting the auxiliary fuel. A fuel injection device for a dual fuel diesel engine, comprising a control unit for controlling the auxiliary fuel injection valve, wherein the auxiliary fuel injection valve is formed in a nozzle body and the nozzle body to assist. A fuel supply unit to which fuel is supplied, a sack unit provided at the tip of the nozzle body and storing auxiliary fuel flowing out from the fuel supply unit, and an auxiliary unit that communicates with the sack unit and is stored in the sack unit. A plurality of fuel injection holes for injecting fuel into the combustion chamber, a nozzle needle provided so as to be movable in the axial direction in the nozzle body and opening and closing a valve hole between the fuel supply portion and the sack portion. The control unit has an inert gas supply mechanism for supplying the inert gas to the sack portion or the plurality of fuel injection holes, and an inert gas cylinder connected to the inert gas supply mechanism, and the control unit is a main fuel. The nozzle needle is controlled so as to close the valve hole during the combustion of the fuel, and the inert gas is supplied from the inert gas cylinder to the sack portion or the plurality of fuel injection holes during the combustion of the main fuel. As described above, the inert gas supply mechanism is controlled.

In the present invention, the control unit controls the nozzle needle so as to close the valve hole during combustion of the main fuel, and supplies the inert gas so that the inert gas is supplied to the sack unit or the plurality of fuel injection holes. Control the mechanism. Since the inert gas is supplied to the sack portion or a plurality of fuel injection holes by the inert gas supply mechanism, the entry of the high temperature combustion gas during combustion into the fuel injection holes and the sack portion is hindered. Therefore, the temperature rise inside the fuel injection hole due to the entry of the combustion gas into the fuel injection hole is suppressed, and the accumulation of deposits in the combustion injection hole and the sack portion can be suppressed.

Further, in the fuel injection device of the dual fuel diesel engine, the inert gas supply mechanism is formed in the nozzle body and flows the inert gas supplied to the sack portion or the plurality of fuel injection holes. A backflow that suppresses the entry of the auxiliary fuel into the inert gas passage is provided in the vicinity of the sack portion or the connection portion with the plurality of fuel injection holes in the inert gas passage. It may be configured to include a suppression mechanism.
In this case, since the inert gas passage is provided with a backflow suppression mechanism, it is possible to suppress the inflow of the auxiliary fuel flowing through the fuel injection hole into the inert gas passage when the auxiliary fuel is injected.

Further, in the fuel injection device of the dual fuel diesel engine, the control unit starts supplying the inert gas to the sack unit or the plurality of fuel injection holes before self-ignition after injection of the auxiliary fuel. The auxiliary fuel injection valve may be controlled so that the supply of the inert gas is continued during the combustion of the main fuel.
In this case, since the inert gas is supplied to the sack portion or a plurality of fuel injection holes during the combustion of the main fuel, the inert gas is injected from the fuel injection holes during the combustion of the main fuel, and the combustion is at a high temperature. It is possible to effectively prevent the gas from entering the fuel injection hole.

The present invention also includes an auxiliary fuel injection valve that is installed in the combustion chamber of a dual fuel diesel engine that uses gaseous fuel as the main fuel and liquid fuel as the auxiliary fuel and can inject the auxiliary fuel, and the auxiliary fuel injection valve. A fuel injection device for a dual fuel diesel engine including a control unit for controlling the above, wherein the auxiliary fuel injection valve is formed in a nozzle body and the nozzle body to supply auxiliary fuel. A sack section provided at the tip of the nozzle body and storing auxiliary fuel flowing out from the fuel supply section, and an auxiliary fuel that communicates with the sack section and is stored in the sack section is injected into the combustion chamber. A plurality of fuel injection holes, a nozzle needle that is provided so as to be movable in the axial direction in the nozzle body and opens and closes a valve hole between the fuel supply portion and the sack portion, and the sack portion or the plurality of fuel injection holes. It has an inert gas supply mechanism for supplying an inert gas to a fuel injection hole, and the inert gas supply mechanism is formed in the nozzle body and is supplied to the sack portion or the plurality of fuel injection holes. It has an inert gas passage for passing the inert gas, and in the vicinity of the sack portion or the connection portion with the plurality of fuel injection holes in the inert gas passage, the auxiliary fuel is connected to the inert gas passage. The plurality of fuel injection holes in the auxiliary fuel injection valve are connected to the independent inert gas passages, and the control unit burns the main fuel. Inside, the nozzle needle is controlled so as to close the valve hole, and the inert gas is supplied so that the inert gas is supplied to the sack portion or the plurality of fuel injection holes during combustion of the main fuel. The mechanism is controlled, and the inert gas supply mechanism is controlled so that the supply timing of the inert gas is different for each fuel injection hole.
In this case, since the timing of supplying the inert gas is different for each fuel injection hole, a very small amount of auxiliary fuel remaining in the sack portion is introduced into the combustion chamber through another fuel injection hole to which the inert gas is not supplied. Can be discharged. Therefore, the amount of auxiliary fuel remaining in the sack portion, which causes the generation of deposit in the fuel injection hole, is reduced, and the accumulation of deposit in the fuel injection hole and its surroundings can be effectively suppressed.

The present invention also includes an auxiliary fuel injection valve that is installed in the combustion chamber of a dual fuel diesel engine that uses gaseous fuel as the main fuel and liquid fuel as the auxiliary fuel and can inject the auxiliary fuel, and the auxiliary fuel injection valve. A fuel injection device for a dual fuel diesel engine including a control unit for controlling the above, wherein the auxiliary fuel injection valve is formed in a nozzle body and the nozzle body to supply auxiliary fuel. A sack section provided at the tip of the nozzle body and storing auxiliary fuel flowing out from the fuel supply section, and an auxiliary fuel that communicates with the sack section and is stored in the sack section is injected into the combustion chamber. A plurality of fuel injection holes, a nozzle needle that is provided so as to be movable in the axial direction in the nozzle body and opens and closes a valve hole between the fuel supply portion and the sack portion, and the sack portion or the plurality of fuel injection holes. It has an inert gas supply mechanism for supplying an inert gas to a fuel injection hole, includes an in-cylinder pressure sensor for detecting the pressure in the combustion chamber, and the inert gas supply mechanism includes an inert gas supply source. A gas compression mechanism connected to the inert gas supply source and compressing the inert gas supplied from the inert gas supply source and supplying the inert gas to the sack portion or the plurality of fuel injection holes is provided. The control unit starts supplying the inert gas to the sack unit or the plurality of fuel injection holes before self-ignition after the injection of the auxiliary fuel, and continues the supply of the inert gas during the combustion of the main fuel. In addition, the auxiliary fuel injection valve is controlled to control the nozzle needle so as to close the valve hole during combustion of the main fuel, and the sack portion or the plurality of fuel injection holes are controlled during combustion of the main fuel. The inert gas supply mechanism is controlled so that the inert gas is supplied to the vehicle, and the pressure of the inert gas of the inert gas supply source is equal to or higher than the maximum value of the pressure in the combustion chamber detected by the in-cylinder pressure sensor. At this time, the inert gas supply mechanism is provided so as to supply the inert gas supplied from the inert gas supply source to the sack portion or the plurality of fuel injection holes without being compressed by the gas compression mechanism. Controlled, when the pressure of the inert gas of the inert gas source is less than the maximum value of the pressure of the combustion chamber detected by the in-cylinder pressure sensor, the inert gas supplied from the inert gas source. The inert gas is supplied so as to compress the gas by the gas compression mechanism and raise the pressure of the inert gas supplied to the sack portion or the plurality of fuel injection holes to the maximum value of the pressure in the combustion chamber. It is characterized by controlling the feeding mechanism.
In this case, when the pressure of the inert gas is equal to or higher than the maximum pressure of the combustion chamber, the inert gas is supplied to the sack portion or a plurality of fuel injection holes, so that the combustion gas is supplied to the fuel injection holes and the sack portion. Can be reliably prevented from entering. Further, when the pressure of the inert gas is less than the maximum value of the pressure in the combustion chamber, the compressor compresses the inert gas and raises the pressure of the inert gas to the maximum value of the pressure in the combustion chamber. Then, the compressed and high-pressure inert gas is supplied to the sack portion or a plurality of fuel injection holes. Therefore, even if the pressure of the inert gas is less than the maximum value of the pressure in the combustion chamber, it is possible to suppress the entry of the combustion gas into the fuel injection hole and the sack portion.

According to the present invention, it is possible to provide a fuel injection device for a dual fuel diesel engine that suppresses deposit accumulation in the fuel injection hole of a fuel injection valve and its surroundings.

It is a figure which shows the outline of the fuel injection device of the dual fuel diesel engine which concerns on embodiment of this invention. It is a main part vertical sectional view of the fuel injection valve which concerns on embodiment of this invention. It is a bottom view which shows the tip part of the fuel injection valve which concerns on embodiment of this invention. It is a graph which shows an example of a heat generation rate, and the timing chart of the injection of auxiliary fuel and an inert gas. It is a flow chart which shows the procedure of injection of an inert gas.

Hereinafter, the fuel injection device of the dual fuel diesel engine according to the embodiment of the present invention will be described with reference to the drawings. The dual fuel diesel engine of the present embodiment is a dual fuel diesel engine mounted on a vehicle. In a dual fuel diesel engine, gaseous fuel (compressed natural gas) as a main fuel and liquid fuel (light oil) as an auxiliary fuel for ignition assistance are used.

As shown in FIG. 1, the fuel injection device (hereinafter referred to as “fuel injection device”) 10 of the dual fuel diesel engine of the present embodiment is referred to as a dual fuel diesel engine (hereinafter referred to as “engine”) as a power source. (Indicated) 11 is installed.

The engine 11 has a plurality of cylinders 13 formed in the cylinder block 12. A piston 14 is provided in each cylinder 13. A combustion chamber 16 is formed in the cylinder 13 by a piston 14 and a cylinder head 15. The piston 14 is slidable in the cylinder 13 of the engine 11 and is connected to the crankshaft (not shown) via a connecting rod (not shown).

An intake port 17 and an exhaust port 18 are formed in the cylinder head 15. The cylinder head 15 is provided with an intake valve 19 for opening and closing the intake port 17 and an exhaust valve 20 for opening and closing the exhaust port 18. The intake port 17 is provided with a main fuel injection valve 21 that injects gaseous fuel, which is the main fuel. Therefore, the gas fuel injected from the main fuel injection valve 21 is mixed with the intake air passing through the intake port 17, and the gas fuel mixed with the air flows into the combustion chamber 16.

The cylinder head 15 is provided with an auxiliary fuel injection valve 22 capable of injecting liquid fuel as an auxiliary fuel so as to face the piston 14. Further, the cylinder head 15 is provided with an in-cylinder pressure sensor 23 that constantly detects the pressure of the combustion chamber 16 formed in the cylinder 13. Details of the auxiliary fuel injection valve 22 will be described later. As shown in FIG. 2, the fuel injection device 10 of the present embodiment includes an auxiliary fuel injection valve 22, an in-cylinder pressure sensor 23, an engine ECU (Electronic Control Unit) 24, an inert gas cylinder 46, an inert gas pipe 47, and a solenoid valve. It is equipped with 48 and a compressor 49.

The auxiliary fuel injection valve 22 is controlled by the engine ECU 24. Although not shown, the engine ECU 24 includes an arithmetic processing unit that performs arithmetic processing and a storage unit that stores various programs, data, and the like. The engine ECU 24 issues a command to each part of the engine 11 to control the operation of the engine 11. The engine ECU 24 determines the fuel injection amount and injection timing of the main fuel injection valve 21 and the auxiliary fuel injection valve 22 based on various information such as the intake air amount and the position of the piston 14 based on the crank angle, and determines the fuel injection amount and the injection timing of the main fuel injection valve 21. And sends a signal to the auxiliary fuel injection valve 22. The main fuel injection valve 21 and the auxiliary fuel injection valve 22 inject fuel at the instructed injection amount and injection timing based on the signal of the engine ECU 24.

Next, the auxiliary fuel injection valve 22 will be described. As shown in FIG. 2, a needle accommodating portion 32 in which the nozzle needle 33 is movably accommodated in the axial direction is formed inside the nozzle body 31 of the auxiliary fuel injection valve 22. The nozzle body 31 is formed with a valve seat 31A on which the tip of the nozzle needle 33 is seated. As shown in FIG. 3, a plurality of fuel injection holes 35 are radially formed at the tip of the nozzle body 31. As shown in FIG. 2, a hollow sack portion 36 that communicates the needle accommodating portion 32 and the fuel injection hole 35 is formed inside the nozzle body 31. In the present embodiment, as shown in FIG. 3, the fuel injection holes 35 are provided at the tip of the nozzle body 31 at intervals of 60 ° in the circumferential direction. Each fuel injection hole 35 communicates the outside of the nozzle body 31 with the sack portion 36.

On the tip side of the needle accommodating portion 32, a fuel supply portion 37 to which auxiliary fuel is supplied by the nozzle body 31 and the nozzle needle 33 is formed as a section. A valve hole 34 is formed by a valve seat 31A between the fuel supply unit 37 and the sack unit 36. The sack portion 36 and the fuel injection hole 35 correspond to the downstream space portion of the valve hole 34. The fuel supply unit 37 communicates with the fuel passage 38 formed inside the nozzle body 31. The fuel passage 38 communicates with the fuel pipe 40 from the common rail 39. The high-pressure auxiliary fuel supplied to the fuel passage 38 through the fuel pipe 40 from the common rail 39 is stored inside in the nozzle body 31, and the movement of the nozzle needle 33 causes the combustion chamber 16 to pass through the sack portion 36 and the fuel injection hole 35. It is injected. When the nozzle needle 33 is seated on the valve seat 31A, the nozzle needle 33 closes the valve hole 34, and the fuel supply unit 37, the sack portion 36 on the downstream side of the valve hole 34, and the fuel injection hole 35 are blocked by the nozzle needle 33. Will be done. The sack unit 36 stores the auxiliary fuel flowing out from the fuel supply unit 37.

A control chamber 41 is partitioned by a nozzle body 31 and a nozzle needle 33 on the proximal end side of the needle accommodating portion 32. The control chamber 41 accommodates a coil spring 42 that urges the nozzle needle 33 in the direction of being seated on the valve seat 31A. The nozzle body 31 is formed with a relief passage 43 that communicates with the control chamber 41. The nozzle body 31 is provided with a solenoid valve 44 that controls communication between the control chamber 41 and the relief passage 43. The control chamber 41 communicates with the fuel passage 38.

The solenoid valve 44 is a solenoid valve provided in the middle of the relief passage 43 and is controlled by the engine ECU 24. The relief passage 43 is communicated or shut off by opening and closing the solenoid valve 44. When the solenoid valve 44 closes the relief passage 43, the pressure in the control chamber 41 rises due to the auxiliary fuel supplied from the fuel passage 38. Then, when the difference between the pressure of the auxiliary fuel in the control chamber 41 and the pressure of the auxiliary fuel in the fuel supply unit 37 becomes less than the urging force of the coil spring 42, the nozzle needle 33 moves in the valve closing direction in which the valve seat 31A is seated. To do.

When the solenoid valve 44 communicates with the relief passage 43, the auxiliary fuel in the control chamber 41 returns from the relief passage 43 to the fuel tank (not shown) through the relief pipe (not shown) connected to the relief passage 43. Therefore, the pressure in the control chamber 41 decreases. Then, when the difference between the pressure in the control chamber 41 and the pressure in the fuel supply unit 37 exceeds the urging force of the coil spring 42, the nozzle needle 33 moves in the valve opening direction away from the valve seat 31A. The engine ECU 24 adjusts the opening / closing and opening / closing speed of the solenoid valve 44 by changing the current control value to the solenoid valve 44. The opening / closing and opening / closing speed of the nozzle needle 33 is controlled by adjusting the opening / closing and opening / closing speed of the solenoid valve 44.

By the way, the auxiliary fuel injection valve 22 of the present embodiment injects an inert gas into each fuel injection hole 35 so as to inject an inert gas from the fuel injection hole 35, which is a space on the downstream side of the valve hole 34, into the combustion chamber 16. It is equipped with an inert gas supply mechanism that supplies fuel. The inert gas supply mechanism includes an inert gas passage 45, an inert gas pipe 47, a solenoid valve 48, and a compressor 49, which will be described later. The nozzle body 31 is formed with an inert gas passage 45 capable of supplying the inert gas to the fuel injection hole 35. One end of the inert gas passage 45 communicates with the fuel injection hole 35 at the downstream connection portion of the sack portion 36, and the other end of the inert gas passage 45 connects to the inert gas pipe 47 connected to the inert gas cylinder 46. Communicating. The inert gas flowing out of the inert gas cylinder 46, which is the inert gas supply source, flows through the inert gas pipe 47 and the inert gas passage 45, and flows into the fuel injection hole 35 from the connection portion downstream of the sack portion 36. The inert gas is a gas that does not affect the combustion of the engine 11, and nitrogen is used in this embodiment.

As shown in FIG. 3, the inert gas passage 45 and the inert gas pipe 47 are provided for each fuel injection hole 35, respectively. That is, independent inert gas passages 45 are connected to the plurality of fuel injection holes 35. The inert gas pipe 47 is provided with a solenoid valve 48 that switches between supplying and shutting off the inert gas to the inert gas passage 45. The solenoid valve 48 is controlled by the engine ECU 24. In the inert gas pipe 47, a compressor 49 as a gas compression mechanism for compressing the inert gas is provided between the inert gas cylinder 46 and the solenoid valve 48. In FIG. 3, the pipe lengths of the respective inert gas pipes 47 are shown differently for convenience of explanation, but they are set to the same pipe lengths.

In the present embodiment, the solenoid valve 48 is controlled so as to sequentially supply and shut off the inert gas to the inert gas passage 45. That is, the solenoid valves 48 do not supply the inert gas to the plurality of fuel injection holes 35 at the same timing, but in order while shifting the timing to the plurality of fuel injection holes 35 (for example, the clock in FIG. 3). The inert gas is supplied in the order of rotation). That is, the timing of supplying the inert gas is different for each fuel injection hole 35. By sequentially supplying the inert gas to the plurality of fuel injection holes 35 at different timings in this way, the auxiliary fuel remaining in the sack portion 36 can be discharged to the outside of the auxiliary fuel injection valve 22. As a method of differentizing the supply timing of the inert gas to the plurality of fuel injection holes 35, in addition to the method of shifting the supply / shutoff timing by the solenoid valve 48, the inert gas pipe 47 connected to each fuel injection hole 35 There is a way to make the pipe length different.

The inert gas passage 45 is provided with a reducer pipe 51 as a backflow suppressing mechanism for suppressing the backflow of auxiliary fuel into the inert gas passage 45. The reducer pipe 51 is arranged near the connection portion with the fuel injection hole 35 in the inert gas passage 45. The reducer pipe 51 includes a cylindrical portion 52 and a tapered tapered pipe portion 53 provided inside the cylindrical portion 52. The tapered pipe portion 53 has a large-diameter opening 54 and a small-diameter opening 55, and is provided so that the small-diameter opening 55 is located on the fuel injection hole 35 side. Since the small-diameter opening 55 of the tapered pipe portion 53 is arranged on the fuel injection hole 35 side, the inflow of the auxiliary fuel from the fuel injection hole 35 into the inert gas passage 45 is suppressed when the auxiliary fuel is injected. .. Further, since the large-diameter opening 54 of the tapered pipe portion 53 is arranged on the side opposite to the side close to the fuel injection hole 35, the inert gas supplied from the inert gas cylinder 46 is vigorously applied to the fuel injection hole 35. Can be shed. By opening the solenoid valve 48, the inert gas is supplied from the inert gas cylinder 46 to the inert gas passage 45. The inert gas supplied to the inert gas passage 45 flows into the fuel injection hole 35 from the connection portion and is injected from the fuel injection hole 35 into the combustion chamber 16.

Next, the injection timing of the inert gas will be described. As can be seen from the graph showing the relationship between the crank angle and the heat generation rate in FIG. 4, since combustion occurs near the top dead center TDC, the heat generation rate near the top dead center TDC is high. On the other hand, as shown in FIG. 4, the injection start timing of the auxiliary fuel is before the piston 14 reaches the top dead center TDC (for example, -30 ° CA), and the injection end timing of the auxiliary fuel is also higher. It is well in front of the dead center TDC. The engine ECU 24 controls the auxiliary fuel injection valve 22 at a timing considerably before the time when the piston 14 reaches the top dead center TDC to inject the auxiliary fuel into the combustion chamber 16.

The timing of starting the supply of the inert gas is after the end of injection of the auxiliary fuel, and the timing of the end of the supply of the inert gas is a specific crank angle past the top dead center TDC. The specific crank angle past the top dead center TDC is, for example, a crank angle indicating a 90% combustion time when 90% of the fuel (main fuel and auxiliary fuel) is burned in the combustion chamber 16. Therefore, the engine ECU 24 controls the solenoid valve 48 so that the inert gas is supplied from the injection of the auxiliary fuel to the combustion of most of the fuel in the combustion chamber 16.

As described above, in the present embodiment, the engine ECU 24 determines the injection amount and injection timing of the auxiliary fuel of the auxiliary fuel injection valve 22 and the supply amount and supply timing of the inert gas based on the position information of the piston 14 based on the crank angle. And sends a signal to the auxiliary fuel injection valve 22. The auxiliary fuel injection valve 22 injects auxiliary fuel at an instructed injection amount and injection timing based on the signal of the engine ECU 24, and supplies an inert gas at the instructed supply amount and supply timing.

In the present embodiment, the procedure for supplying the inert gas follows the flow chart shown in FIG. First, the engine ECU 24 detects the pressure in the combustion chamber 16 and the pressure of the inert gas (see step S1). The maximum pressure value of the combustion chamber 16 refers to the highest pressure among the pressures of the combustion chamber 16 detected by the in-cylinder pressure sensor 23. The pressure of the inert gas is detected by a pressure sensor (not shown) connected to the inert gas cylinder 46.

Next, the engine ECU 24 determines whether or not the pressure of the inert gas in the inert gas cylinder 46 is equal to or higher than the maximum pressure value of the combustion chamber 16 detected by the in-cylinder pressure sensor 23 (see step S2). When the engine ECU 24 determines that the pressure of the inert gas in the inert gas cylinder 46 is equal to or greater than the maximum pressure value of the combustion chamber 16 detected by the in-cylinder pressure sensor 23, the supply period of the inert gas is calculated (see step S3). ). After calculating the supply period of the inert gas, the engine ECU 24 supplies the inert gas without compressing the inert gas with the compressor 49 (see step S4). In step S2, when the engine ECU 24 determines that the pressure of the inert gas in the inert gas cylinder 46 is not equal to or higher than the maximum pressure value of the combustion chamber 16 detected by the in-cylinder pressure sensor 23, the inert gas supplied from the inert gas cylinder 46 is inactive. The gas is compressed by the compressor 49 to the maximum value of the combustion chamber pressure detected by the in-cylinder pressure sensor 23 (see step S5). That is, the engine ECU 24 compresses the inert gas supplied from the inert gas cylinder 46 by the compressor 49 and brings the pressure of the inert gas supplied to the plurality of fuel injection holes 35 to the maximum value of the pressure in the combustion chamber 16. The inert gas supply mechanism is controlled so as to raise it. When the inert gas of the inert gas cylinder 46 is compressed by the compressor 49 to the maximum value of the combustion chamber pressure detected by the in-cylinder pressure sensor 23, the process proceeds to step S3.

Next, the operation of the fuel injection device 10 of the present embodiment will be described. When the engine 11 is in operation, the intake air passing through the intake port 17 is mixed with the gaseous fuel injected from the main fuel injection valve 21 and flows into the combustion chamber 16 by the lowering of the piston 14. As the piston 14 rises, the main fuel premixed with the air in the combustion chamber is compressed. Auxiliary fuel is injected from the auxiliary fuel injection valve 22 well before the piston 14 reaches top dead center TDC. When the auxiliary fuel becomes high pressure due to the compression of the piston 14 and self-ignites, the main fuel burns together with the auxiliary fuel. The piston 14 descends due to expansion due to combustion of the main fuel and auxiliary fuel in the combustion chamber 16. The downward motion of the piston 14 is converted into the rotational motion of the crankshaft via the connecting rod, and the driving force of the engine 11 is obtained.

After the auxiliary fuel is injected by the auxiliary fuel injection valve 22, the inert gas is supplied to the fuel injection hole 35, and the supply of the inert gas is continued until most of the fuel is burned in the combustion chamber 16. The supply of the inert gas to the fuel injection hole 35 prevents the high-temperature combustion gas from entering the fuel injection hole 35 in the combustion chamber 16, and also suppresses the temperature rise inside the fuel injection hole 35. Since the engine ECU 24 controls the solenoid valve 48 so that the supply timing of the inert gas is different for each fuel injection hole 35, the inert gas is ordered (for example, for example) while shifting the timing with respect to the plurality of fuel injection holes 35. It is supplied in the clockwise order in FIG. Therefore, a very small amount of auxiliary fuel remaining in the fuel injection hole 35 and the sack portion 36 can be discharged into the combustion chamber 16 through another fuel injection hole 35 to which the inert gas is not supplied. .. Therefore, the amount of auxiliary fuel remaining in the sack portion 36, which causes the generation of deposits in the fuel injection hole 35, is reduced, and the accumulation of deposits in the fuel injection hole 35 and its surroundings can be effectively suppressed. When the pressure of the inert gas is equal to or higher than the maximum pressure value of the combustion chamber 16, the inert gas is supplied without compression, but when the pressure of the inert gas is not equal to or higher than the maximum pressure value of the combustion chamber 16, it is not possible. The active gas is compressed to the maximum value of the combustion chamber pressure by the compressor 49, and then the inert gas is supplied. That is, after adjusting the pressure of the inert gas, the inert gas is supplied to the fuel injection hole 35.

The fuel injection device 10 of the present embodiment has the following effects.
(1) The engine ECU 24 as a control unit controls the nozzle needle 33 so as to close the valve holes 34 during combustion of the main fuel, and does not supply the inert gas to the plurality of fuel injection holes 35. Control the active gas supply mechanism. Since the inert gas is supplied to the fuel injection hole 35 through the inert gas passage 45, the entry of the high temperature combustion gas into the fuel injection hole 35 and the sack portion 36 is hindered. Therefore, the temperature rise inside the fuel injection hole 35 due to the entry of the combustion gas into the fuel injection hole 35 is suppressed, and the accumulation of deposits in the fuel injection hole 35 and the sack portion 36 can be suppressed.

(2) A reducer pipe 51 is provided in the vicinity of the connection portion with the fuel injection hole 35 in the inert gas passage 45. Therefore, the reducer pipe 51 can suppress the inflow of the auxiliary fuel flowing through the fuel injection hole 35 into the inert gas passage 45 at the time of injection of the auxiliary fuel, and can prevent the deposit accumulation in the inert gas passage 45. ..

(3) Since the engine ECU 24 as a control unit supplies the inert gas to the fuel injection hole 35 during the combustion of the main fuel in the combustion chamber 16, the inert gas is injected from the fuel injection hole 35 during the combustion of the main fuel. Therefore, it is possible to effectively prevent the high-temperature combustion gas from entering the fuel injection hole 35.

(4) Since the timing of supplying the inert gas is different for each fuel injection hole 35, a very small amount of auxiliary fuel remaining in the sack portion 36 is passed through another fuel injection hole 35 to which the inert gas is not supplied. It can be discharged into the combustion chamber 16. Therefore, the amount of auxiliary fuel remaining in the sack portion 36, which causes the generation of deposits in the fuel injection hole 35, is reduced, and the accumulation of deposits in the fuel injection hole 35 and its surroundings can be effectively suppressed.

(5) The engine ECU 24 supplies the inert gas to the fuel injection hole 35 when the pressure of the inert gas is equal to or higher than the maximum value of the pressure of the combustion chamber 16 detected by the in-cylinder pressure sensor 23. Since the inert gas having a pressure equal to or higher than the pressure of the combustion gas is supplied to the fuel injection hole 35 and the sack portion 36, it is possible to reliably prevent the combustion gas from entering the fuel injection hole 35 and the sack portion 36. Further, when the pressure of the inert gas is less than the maximum value of the pressure of the combustion chamber 16 detected by the in-cylinder pressure sensor 23, the engine ECU 24 compresses the inert gas with the compressor 49 to obtain the inert gas. The pressure is raised to the maximum value of the pressure in the combustion chamber 16. Then, the compressed inert gas is supplied to the fuel injection hole 35. Since the inert gas compressed to the maximum value of the pressure of the combustion chamber 16 or more is supplied to the fuel injection hole 35, the intrusion of the combustion gas into the fuel injection hole 35 and the sack portion 36 can be suppressed.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the invention. For example, the present invention may be modified as follows.

○ In the above embodiment, the backflow suppression mechanism is provided near the connection portion with the plurality of fuel injection holes in the inert gas passage, but the backflow suppression mechanism is not essential. For example, the backflow suppression mechanism may not be provided in the inert gas passage.
○ In the above embodiment, the inert gas passage communicating with the fuel injection hole is provided, but this is not the case. For example, the inert gas passage may be communicated with the sack portion. In this case, the number of the inert gas passage can be one, and the auxiliary fuel remaining in the sack portion can be more easily discharged.
○ In the above embodiment, the inert gas is supplied during the period from the timing after the injection of the auxiliary fuel to the timing of the 90% combustion timing, but the present invention is not limited to this. The timing of starting the supply of the inert gas may be, for example, after the injection of the auxiliary fuel and before the self-ignition of the auxiliary fuel, and the timing of the end of supply is the latter half of the combustion period (for example, the combustion period after 70%). ) Timing is sufficient. Further, the inert gas or air may be supplied to the fuel injection hole in the exhaust stroke in which the high temperature combustion gas remains in the combustion chamber.
○ In the above embodiment, the inert gas is used, but the inert gas and air may be switched and used. In this case, when the inert gas is exhausted, air may be supplied to the sack portion or a plurality of fuel injection holes as a substitute for the inert gas, and the injection of air can prevent the accumulation of deposits. it can.
○ In the above embodiment, when the pressure of the inert gas is less than the maximum value of the pressure in the combustion chamber detected by the in-cylinder pressure sensor, the inert gas is compressed by the compressor to burn the pressure of the inert gas. The pressure in the chamber was raised to the maximum, but this is not the case. For example, an inert gas having a pressure less than the maximum value of the combustion chamber may be supplied to the sack portion or a plurality of fuel injection holes without being compressed. In this case, the inert gas may be supplied to the sack portion or the plurality of fuel injection holes. Compared with the case where it is not supplied, the effect of preventing the combustion gas from entering the fuel injection hole can be expected.
○ In the above embodiment, nitrogen is used as the inert gas, but rare gases such as helium, neon, argon, krypton, xenon, and radon may be used.

10 Fuel injection device 11 Engine 13 Cylinder 14 Piston 16 Combustion chamber 21 Main fuel injection valve 22 Auxiliary fuel injection valve 23 In-cylinder pressure sensor 24 Engine ECU (as a control unit)
31 Nozzle body 31A Valve seat 32 Needle accommodating part 33 Nozzle needle 34 Valve hole 35 Fuel injection hole 36 Sack part 45 Inert gas passage 46 Inert gas cylinder 47 Inert gas piping 48 Electromagnetic valve 49 Compressor 51 Reducer pipe TDC Top dead point

Claims (5)

An auxiliary fuel injection valve that is installed in the combustion chamber of a dual fuel diesel engine that uses gaseous fuel as the main fuel and liquid fuel as the auxiliary fuel and can inject the auxiliary fuel.
A fuel injection device for a dual fuel diesel engine, comprising a control unit for controlling the auxiliary fuel injection valve.
The auxiliary fuel injection valve is
Nozzle body and
A fuel supply unit formed in the nozzle body and supplied with auxiliary fuel,
A sack portion provided at the tip of the nozzle body and storing auxiliary fuel flowing out from the fuel supply portion, and a sack portion.
A plurality of fuel injection holes that communicate with the sack portion and inject auxiliary fuel stored in the sack portion into the combustion chamber.
A nozzle needle that is provided so as to be movable in the axial direction in the nozzle body and opens and closes a valve hole between the fuel supply portion and the sack portion.
An inert gas supply mechanism that supplies the inert gas to the sack portion or the plurality of fuel injection holes .
It has an inert gas cylinder connected to the inert gas supply mechanism .
The control unit controls the nozzle needle so as to close the valve hole during combustion of the main fuel, and from the inert gas bomb to the sack unit or the plurality of fuel injection holes during combustion of the main fuel. A fuel injection device for a dual fuel diesel engine, characterized in that the inert gas supply mechanism is controlled so that the inert gas is supplied. The inert gas supply mechanism is formed in the nozzle body and has an inert gas passage through which the inert gas supplied to the sack portion or the plurality of fuel injection holes is circulated.
A backflow suppressing mechanism for suppressing the entry of the auxiliary fuel into the inert gas passage is provided in the vicinity of the sack portion or the connection portion with the plurality of fuel injection holes in the inert gas passage. The fuel injection device for a dual fuel diesel engine according to claim 1. The control unit starts supplying the inert gas to the sack unit or the plurality of fuel injection holes before self-ignition after injection of the auxiliary fuel, and continues to supply the inert gas during combustion of the main fuel. The fuel injection device for a dual fuel diesel engine according to claim 1 or 2, wherein the auxiliary fuel injection valve is controlled as described above. An auxiliary fuel injection valve that is installed in the combustion chamber of a dual fuel diesel engine that uses gaseous fuel as the main fuel and liquid fuel as the auxiliary fuel and can inject the auxiliary fuel.
A fuel injection device for a dual fuel diesel engine, comprising a control unit for controlling the auxiliary fuel injection valve.
The auxiliary fuel injection valve is
Nozzle body and
A fuel supply unit formed in the nozzle body and supplied with auxiliary fuel,
A sack portion provided at the tip of the nozzle body and storing auxiliary fuel flowing out from the fuel supply portion, and a sack portion.
A plurality of fuel injection holes that communicate with the sack portion and inject auxiliary fuel stored in the sack portion into the combustion chamber.
A nozzle needle that is provided so as to be movable in the axial direction in the nozzle body and opens and closes a valve hole between the fuel supply portion and the sack portion.
It has an inert gas supply mechanism that supplies the inert gas to the sack portion or the plurality of fuel injection holes.
The inert gas supply mechanism is formed in the nozzle body and has an inert gas passage through which the inert gas supplied to the sack portion or the plurality of fuel injection holes is circulated.
In the vicinity of the sack portion or the connection portion with the plurality of fuel injection holes in the inert gas passage, a backflow suppressing mechanism for suppressing the entry of the auxiliary fuel into the inert gas passage is provided.
Independent independent gas passages are connected to the plurality of fuel injection holes in the auxiliary fuel injection valve.
The control unit
The nozzle needle is controlled so as to close the valve hole during combustion of the main fuel, and the inert gas is supplied to the sack portion or the plurality of fuel injection holes during combustion of the main fuel. Control the inert gas supply mechanism,
Fuel injection device for a secondary way fuel diesel engine you characterized in that the supply timing of the inert gas to each of the fuel injection hole to control the inert gas supply mechanism differently. An auxiliary fuel injection valve that is installed in the combustion chamber of a dual fuel diesel engine that uses gaseous fuel as the main fuel and liquid fuel as the auxiliary fuel and can inject the auxiliary fuel.
A fuel injection device for a dual fuel diesel engine, comprising a control unit for controlling the auxiliary fuel injection valve.
The auxiliary fuel injection valve is
Nozzle body and
A fuel supply unit formed in the nozzle body and supplied with auxiliary fuel,
A sack portion provided at the tip of the nozzle body and storing auxiliary fuel flowing out from the fuel supply portion, and a sack portion.
A plurality of fuel injection holes that communicate with the sack portion and inject auxiliary fuel stored in the sack portion into the combustion chamber.
A nozzle needle that is provided so as to be movable in the axial direction in the nozzle body and opens and closes a valve hole between the fuel supply portion and the sack portion.
It has an inert gas supply mechanism that supplies the inert gas to the sack portion or the plurality of fuel injection holes.
A cylinder pressure sensor for detecting the pressure in the combustion chamber is provided.
The inert gas supply mechanism is connected to the inert gas supply source and the inert gas supply source, and compresses the inert gas supplied from the inert gas supply source to the sack portion or the plurality of. Equipped with a gas compression mechanism that supplies fuel to the fuel injection holes
The control unit
The auxiliary gas is started to be supplied to the sack portion or the plurality of fuel injection holes before self-ignition after the injection of the auxiliary fuel, and the supply of the inert gas is continued during the combustion of the main fuel. Control the fuel injection valve,
The nozzle needle is controlled so as to close the valve hole during combustion of the main fuel, and the inert gas is supplied to the sack portion or the plurality of fuel injection holes during combustion of the main fuel. Control the inert gas supply mechanism,
When the pressure of the inert gas of the inert gas supply source is equal to or higher than the maximum value of the pressure of the combustion chamber detected by the in-cylinder pressure sensor, the inert gas supplied from the inert gas supply source is referred to as described above. The inert gas supply mechanism is controlled so as to supply the sack portion or the plurality of fuel injection holes without being compressed by the gas compression mechanism.
When the pressure of the inert gas of the inert gas supply source is less than the maximum value of the pressure of the combustion chamber detected by the in-cylinder pressure sensor, the inert gas supplied from the inert gas supply source is referred to as described above. Controlling the inert gas supply mechanism so as to raise the pressure of the inert gas compressed by the gas compression mechanism and supplied to the sack portion or the plurality of fuel injection holes to the maximum value of the pressure in the combustion chamber. fuel injection device for a secondary way fuel diesel engine you characterized.

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