JPH11173234A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the interval between a pilot injection and a main injection and simultaneously to lower the initial injection rate of an injector. SOLUTION: An orifice forming member 7 partitioning into a first control chamber 24 providing the shoulder 34 of a command piston 9 with hydraulic force in the nozzle closing direction and a second control chamber 25 providing the head 35 of the command piston 9 with hydraulic force in the nozzle closing direction is fitted into the rear end of an injector body 6. The center of a ring- shaped portion of the injector body 6 is provided with an orifice 27 for communicating a fuel feeding and discharging passage 13 with the second control chamber 25. An axial groove formed of a fuel passage of a larger passage sectional area than the orifice 27 between the inner circumferential surfaces of the injector body 6 is provided on the outer circumferential surface of the ring-shaped portion of the orifice forming member 7. Thus the time from opening a control valve 2 to the start of the action of a nozzle needle 4 in the valve opening direction can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve for supplying high-pressure fuel stored in a common rail to an internal combustion engine, and more particularly to a pressure-accumulation type fuel injection device for an internal combustion engine capable of reducing an initial injection rate. Related to the fuel injection valve.

[0002]

2. Description of the Related Art Conventionally, a pressure accumulating fuel injection device for an internal combustion engine for injecting high pressure fuel accumulated in a common rail into an internal combustion engine has been known. This accumulator type fuel injection device includes:
In order to perform stable combustion from the start of the main injection and to suppress the vibration of the internal combustion engine, the solenoid-operated on-off valve is opened twice so that a small amount of high pressure is applied before the main injection (so-called main injection). The fuel is injected in advance (so-called pilot injection).

[0003] As a fuel injection valve for an internal combustion engine used in the above-described accumulator type fuel injection device, FIG.
There is an injector 100 shown in (b) (first conventional example). The injector 100 of the first conventional example includes a nozzle needle 103 for opening and closing an injection hole 102 formed at a tip end portion of a nozzle body 101, and a nozzle needle 10.
Between the inner periphery of the injector body 105 and the head, and a coil spring 104 for urging the control chamber 3 in the valve closing direction.
And a command piston 107 forming the same.
Reference numeral 108 denotes an oil reservoir in which high-pressure fuel is constantly supplied from a common rail via a fuel supply passage 109. Reference numeral 110 denotes a piston rod for integrating the nozzle needle 103 and the command piston 107.

[0004] As shown in FIG. 11 (a), a fuel supply passage 1 communicating the common rail with the control chamber 106 is provided.
An orifice 112 is provided in 11, and a two-way electromagnetic on-off valve (hereinafter abbreviated as an electromagnetic valve) 115 is provided in a fuel discharge passage 114 that connects the control chamber 106 and the fuel tank 113. As shown in FIG. 11B, an orifice forming member 118 sandwiched between an upper end of the injector body 105 and an annular member 116 has a control chamber 106, a fuel supply passage 111, and a fuel discharge passage. Passage 1
14 is formed.

On the other hand, as a fuel injection valve for an internal combustion engine that does not perform pilot injection, there is an injector 200 shown in FIGS. 12A and 12B (second conventional example). The injector 200 of the second conventional example has a nozzle body 201, an injection hole 202, and a nozzle needle 20 similarly to the first conventional example.
3, coil spring 204, injector body 20
5, control chamber 206, command piston 207, oil sump 208, fuel supply passage 209, and piston rod 21
0 is provided.

[0006] As shown in FIG. 12 (a), a fuel supply passage 2 communicating the common rail and the control chamber 206 is provided.
An orifice 212 is provided in 11, and a two-way electromagnetic on-off valve (hereinafter abbreviated as an electromagnetic valve) 215 is provided in a fuel discharge passage 214 communicating the control chamber 206 and the fuel tank 213. As shown in FIG. 12B, the control chamber 206 and the fuel discharge passage 214 communicate with the orifice forming member 218 sandwiched between the upper end of the injector body 205 and the annular member 216. An orifice 219 is formed.

[0007]

However, in the injector 100 of the first conventional example, since the high-pressure fuel flows out or in the control chamber 106 through the orifice 119, the pressure change speed of the control chamber 106 is small. .
Therefore, it takes time from when the solenoid valve 115 is opened or closed to when the nozzle needle 103 starts to be displaced in the vertical direction. This causes a problem that the minimum interval from the end of the pilot injection to the start of the main injection increases. When the passage cross-sectional area of the orifice 119 shown in FIG. 11B is further reduced for the purpose of reducing the generation of nitrogen oxides by reducing the initial injection rate of the injector 100, the minimum interval is further increased. Problems arise. Therefore, shortening of the interval of pilot injection and reduction of the initial injection rate cannot be achieved at the same time.

On the other hand, in the injector 200 of the second conventional example, the control chamber 206 presses the high-pressure fuel with respect to the cross-sectional area of the orifice 212 provided in the fuel supply passage 211 for supplying high-pressure fuel into the control chamber 206. By increasing the cross-sectional area of the orifice 219 provided in the fuel discharge passage 214 for discharging fuel, the valve opening speed of the nozzle needle 203 is increased. That is, since the oil pressure in the valve opening direction of the seat portion 220 of the nozzle needle 203 can be rapidly increased, the pressure loss of the fuel passage (gap) formed between the seat portion 220 and the nozzle body 201 is reduced. Accordingly, atomization of the high-pressure fuel injected from the injection holes 202 can be promoted.

Contrary to the above, in the injector 200 of the second conventional example, the valve opening speed of the nozzle needle 203 is reduced by making the passage sectional area of the orifice 219 smaller than that of the orifice 212. Become slow.
That is, since the injection amount of the high-pressure fuel injected from the injection hole 202 can be suppressed, the initial injection rate of the injector 200 can be reduced. However, in the specification of the injector 200 of the second conventional example, since the relationship between the passage cross-sectional area of the orifice 212 and the passage cross-sectional area of the orifice 219 is always constant, it is necessary to promote the atomization of the high-pressure fuel and reduce the initial injection rate. Could not be achieved at the same time.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection valve capable of reducing the initial injection rate while shortening the pilot injection interval. Another object of the present invention is to provide a fuel injection valve capable of promoting atomization at the time of injection of high-pressure fuel and reducing the initial injection rate.

[0011]

Means for Solving the Problems Claims 1 and 2
According to the invention, when the on-off valve is opened, the high-pressure fuel in the first control chamber and the second control chamber is discharged to the fuel discharge passage through the fuel supply / discharge passage. At this time, the high-pressure fuel in the first control chamber is discharged earlier than the high-pressure fuel in the second control chamber because there is no fixed throttle in the discharge path. For this reason, it is possible to quickly reduce the pressure in the valve closing direction that is received by a part of the piston, and it is possible to accelerate the displacement of the nozzle needle in the valve opening direction. At the same time, the second
The high-pressure fuel in the control chamber is discharged later than the high-pressure fuel in the first control chamber due to the presence of the fixed throttle in the discharge path. For this reason, it is possible to moderately reduce the pressure in the valve closing direction that is received by the remaining portion of the piston, so that the initial injection rate of the fuel injection valve can be reduced.

According to the third aspect of the present invention, when the on-off valve is closed, the high pressure from the fuel accumulator passes through the fuel supply passage, the fuel supply / discharge passage and the fixed throttle to the first control chamber and the second control chamber. Fuel is supplied. At this time, the supply of the high-pressure fuel to the first control chamber is performed earlier than the supply of the high-pressure fuel to the second control chamber. For this reason, it is possible to rapidly increase the pressure in the valve closing direction that is received by a part of the piston, and it is possible to accelerate the displacement of the nozzle needle in the valve closing direction.
Thus, the valve opening response and the valve closing response of the nozzle needle can be improved, so that the minimum interval between the pilot injection and the main injection can be shortened.

According to the fourth and fifth aspects of the present invention, when the on-off valve is opened, the high-pressure fuel in the control chamber is discharged to the fuel discharge passage through the outflow-side communication passage. At this time, since the inflow-side communication passage is narrower than the outflow-side communication passage, a small amount of high-pressure fuel is supplied to the control chamber through the inflow-side communication passage. For this reason, the pressure in the valve closing direction that the piston receives can be quickly reduced, and the displacement of the nozzle needle in the valve opening direction can be accelerated. As a result, the time from when the on-off valve opens to when the nozzle needle opens can be shortened, and the valve opening responsiveness of the fuel injection valve can be improved. Further, in the initial stage of opening the nozzle needle, the pressure loss in the fuel passage formed between the nozzle needle and the nozzle body is reduced, so that atomization of the high-pressure fuel injected from the injection hole can be promoted.

When the nozzle needle rises by a predetermined amount in the valve opening direction, the amount of high-pressure fuel supplied to the control chamber through the inflow-side passage increases. For this reason, the rate of decrease in the pressure in the valve closing direction that the piston receives starts to decrease, and the displacement speed of the nozzle needle in the valve opening direction can be suppressed, so that the initial injection rate of the fuel injection nozzle can be reduced. .

According to the sixth and seventh aspects of the present invention, when the on-off valve is opened, the high-pressure fuel in the control chamber is discharged from the first chamber.
The fuel is discharged to the fuel discharge passage through the communication passage, the second communication passage, and the fuel supply / discharge passage. At this time, since the first communication passage is narrower than the second communication passage, the second communication passage that is wider than the first communication passage is formed.
The high-pressure fuel in the control chamber is quickly discharged through the communication passage. For this reason, the pressure in the valve closing direction that the piston receives can be quickly reduced, and the displacement of the nozzle needle in the valve opening direction can be accelerated. As a result, the time from when the on-off valve opens to when the nozzle needle opens can be shortened, and the valve opening responsiveness of the fuel injection valve can be improved. Also,
At the initial stage of opening the nozzle needle, the pressure loss in the fuel passage formed between the nozzle needle and the nozzle body is reduced, so that atomization of the high-pressure fuel injected from the injection hole can be promoted.

Then, when the nozzle needle rises by a predetermined amount in the valve opening direction, for example, the first needle having a fixed throttle is provided.
High-pressure fuel discharged from the control chamber through the communication passage increases. For this reason, since the discharge amount of the high-pressure fuel from the control chamber decreases, the speed at which the piston receives the pressure in the valve closing direction starts to decrease, and the displacement speed of the nozzle needle in the valve opening direction can be suppressed. Therefore, the initial injection rate of the fuel injection nozzle can be reduced.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Structure of First Embodiment] FIGS. 1 and 2 show a first embodiment of the present invention.
FIG. 1 is a diagram illustrating a main configuration of a pressure accumulating fuel injection device for an internal combustion engine, and FIG. 1B is a diagram illustrating a main configuration of an injector.

The accumulator type fuel injection device for an internal combustion engine according to the present embodiment is an engine control device (hereinafter referred to as an ECU) not shown.
High-pressure pump (not shown) electronically controlled by the ECU, a common rail (not shown) to which high-pressure fuel is supplied from the high-pressure pump, and a fuel injection valve (fuel injection nozzle: Injector)
1 is provided. Here, the ECU calculates an optimal injection amount and injection timing based on information from various sensors such as an engine rotation speed sensor, a control rack position sensor, an injection timing (advance angle) sensor, and an accelerator (throttle) opening degree sensor. The actuators such as the high-pressure pump and the injector 1 are electronically controlled.

The high-pressure pump includes a feed pump (not shown) for pumping fuel from the fuel tank 10 and a supply pump (not shown) for discharging the fuel pumped by the feed pump to a high pressure. It is configured. Further, the common rail has a relatively high pressure (common rail pressure: for example, 20 MPa to 120 MPa).
A type of surge tank for accumulating high-pressure fuel of a), which is provided so as to communicate with an injector 1 attached to each cylinder of, for example, a diesel engine (hereinafter referred to as an internal combustion engine).

Next, the configuration of the injector 1 of the present embodiment will be briefly described with reference to FIG. This injector 1
A solenoid valve (electromagnetic valve: hereinafter referred to as a control valve) 2 provided in the middle of the drain passage 11, a nozzle needle 4 slidably supported in the nozzle body 3, a fuel supply passage 12, The cylinder 5 is configured to supply and discharge high-pressure fuel through a fuel supply / discharge passage 13 communicating with both of the drain passages 11, and a command piston 9 slidably supported in the cylinder 5. In the middle of the fuel supply passage 12, an orifice (fixed throttle) 14 for reducing the cross-sectional area of the passage is provided.

The drain passage 11 corresponds to the fuel discharge passage of the present invention, and communicates the fuel supply / discharge passage 13 with the fuel tank 10 to discharge high-pressure fuel from the control chamber of the cylinder 5. The fuel supply passage 12 communicates the common rail with the fuel supply / discharge passage 13 to supply high-pressure fuel into the control chamber of the cylinder 5.

The control valve 2 opens the drain passage 1 at the optimal time.
This is a two-way solenoid valve that is energized and controlled by the ECU to open the solenoid valve 1. This control valve 2 is, specifically, a drain passage 1
1 for opening and closing a valve body, an electromagnetic coil for opening the valve body by attracting the valve body when energized, and for closing the valve body when energization to this electromagnetic coil is stopped. Has a known structure including a return spring (both not shown).

The nozzle body 3 is attached to each cylinder of the internal combustion engine. At the tip of the nozzle body 3,
A plurality of injection holes 15 are provided for injecting high-pressure fuel into each cylinder of the internal combustion engine. On the tip side of the nozzle body 3, that is, around the tip of the nozzle needle 4, there is formed an oil sump 17 into which high-pressure fuel is always introduced from the common rail via the fuel supply passage 16.

The nozzle needle 4 has a seat portion 18 which sits on the seat of the nozzle body 3 when the valve is closed. When the nozzle needle 4 opens (rises), a fuel passage through which high-pressure fuel passes is formed between the seat portion of the nozzle body 3 and the seat portion 18. A coil spring 19 is provided between the rear end of the nozzle needle 4 and the cylinder 5.
Are arranged. The coil spring 19 is urging means for urging the nozzle needle 4 in the valve closing direction, and is also valve opening pressure determining means for determining the valve opening pressure of the nozzle needle 4.

The cylinder 5 includes an injector body 6 connected to the rear end face of the nozzle body 3 and an orifice forming member 7 fitted to the rear end of the injector body 6.
And an annular plate member 8 connected to the rear end face of the injector body 6. As shown in FIG. 1B, a cylindrical sliding portion 2 that slidably supports the outer peripheral surface of the command piston 9 is provided at the rear end of the injector body 6.
1 and a cylindrical fitting portion 22 provided on the rear end side of the sliding portion 21 and having an inner diameter larger than that of the sliding portion 21.

The orifice forming member 7 is a portion corresponding to the partitioning portion of the present invention, and is fitted into the fitting portion 22 so as to abut on the step portion 23 of the injector body 6, and applies a back pressure to the command piston 9. The given control room is the first control room 2
4 and a second control room 25. The orifice forming member 7 has an annular portion disposed so as to be flush with the rear end surface of the injector body 6 and a cylindrical portion extending from the end of the annular portion to the distal end side. doing.

On the outer peripheral surface of the orifice forming member 7, an axial groove for forming a fuel passage 26 is formed between the orifice forming member 7 and the inner peripheral surface of the fitting portion 22. The fuel passage 26 communicates the fuel supply / discharge passage 13 with the first control chamber 24. Further, at the center of the annular portion of the orifice forming member 7,
An orifice 27 that connects the fuel supply / discharge passage 13 with the second control chamber 25 is formed.

The orifice 27 has a passage cross-sectional area smaller than that of the fuel passage 26, and the fuel supply / discharge passage 13 and the second control chamber 25
And a tapered passage whose inner diameter gradually decreases from the fuel supply / discharge passage 13 side toward the second control chamber 25 side. This allows
The flow velocity of the high-pressure fuel flowing into the second control chamber 25 through the orifice 27 is higher than the discharge flow velocity of the high-pressure fuel discharged through the orifice 27 into the fuel supply / discharge passage 13.

The annular plate member 8 is assembled to the rear end face of the fitting section 22 with the orifice forming member 7 sandwiched between the annular plate member 8 and the injector body 6. This annular plate member 8
Is provided with a fuel supply / discharge passage 13. The inner diameter of the fuel supply / discharge passage 13 is substantially the same as the inner diameter of the sliding portion 21, and is smaller than the inner diameter of the fitting portion 22.

The command piston 9 has a cylindrical large-diameter portion 30 slidably supported on the inner peripheral surface of the sliding portion 21 and the inner peripheral surface of the cylindrical portion of the orifice forming member 7 slidably. And a cylindrical small-diameter portion 31 that is supported. From the tip end surface (lower end surface in the figure) of the large diameter portion 30, a round bar-shaped pin portion 3 connecting the large diameter portion (sliding portion) of the nozzle needle 4 is formed.
3 are provided so as to protrude. Thereby, the command piston 9 is displaced in conjunction with the nozzle needle 4. That is, the nozzle needle 4 rises at the same time as rising, and falls at the same time as the nozzle needle 4 descends.

An annular shoulder portion 34 is formed on the rear end face of the large diameter portion 30 to receive the oil pressure in the nozzle closing direction by the high-pressure fuel in the first control chamber 24. The small diameter portion 31 is provided so as to protrude rearward from the upper end surface of the large diameter portion 30 in the figure. A circular head 35 is formed on the rear end face of the small diameter portion 31 to receive the oil pressure in the nozzle closing direction by the high-pressure fuel in the second control chamber 25.

Therefore, the first control chamber 24 includes the inner peripheral surface on the rear end side of the sliding portion 21 of the injector body 6, the distal end surface of the cylindrical portion of the orifice forming member 7, and the small diameter portion 31 of the command piston 9. And a first back pressure chamber for applying an oil pressure to the shoulder 34 in the nozzle closing direction. In addition, the second control room 25
This is a space surrounded by the tip surface of the annular portion of the orifice forming member 7, the inner peripheral surface of the cylindrical portion, and the head 35 of the command piston 9, and the head 35 has oil in the nozzle closing direction. This is a second back pressure chamber for applying pressure.

[Operation of the First Embodiment] Next, the operation of the accumulator type fuel injection device for an internal combustion engine of the present embodiment will be briefly described with reference to FIGS. Here, FIG. 2 is a graph showing the relationship between the opening / closing state of the control valve 2 and the needle lift. The broken line in FIG. 2 indicates the injector 1 of the first conventional example.
00 shows a needle lift of 00.

1) When the control valve 2 is opened When the control valve 2 communicating with the fuel tank 10 is opened by being electronically controlled by the ECU, the high-pressure fuel filled in the first control chamber 24 is filled with fuel. The high-pressure fuel filling the second control chamber 25 starts flowing out through the passage 26 and the fuel supply / discharge passage 13 and the orifice 27 and the fuel supply / discharge passage 13
Start spilling through.

At this time, since the high-pressure fuel in the first control chamber 24 flows out earlier than the high-pressure fuel in the second control chamber 25,
Since the internal pressure (P1) of the first control chamber 24 drops more rapidly than the internal pressure (P2) of the second control chamber 25, the oil pressure in the nozzle closing direction which is received by the shoulder 34 of the command piston 9 quickly. Reduce. That is, the urging force in the nozzle closing direction that the nozzle needle 4 receives from the coil spring 19 and the shoulder of the command piston 9 with respect to the oil pressure in the nozzle opening direction that the nozzle needle 4 receives from the high-pressure fuel in the oil reservoir 17. The hydraulic pressure applied to the nozzle 34 and the head 35 in the nozzle closing direction is reduced.

As a result, as shown by the solid line in FIG. 2, the time from when the control valve 2 is opened to when the command piston 9 and the nozzle needle 4 start operating in the upward direction is reduced. When the nozzle needle 4 rises, a plurality of injection holes 15 pass from the oil reservoir 17 through a fuel passage formed between the nozzle body 3 and the seat portion 18.
Starts fuel injection into the internal combustion engine.

The high-pressure fuel in the second control chamber 25 is
Since the fuel flows out later than the high-pressure fuel in the control room 24, the second
Since the internal pressure (P2) of the control chamber 25 decreases more gradually than the internal pressure (P1) of the first control chamber 24, the oil pressure in the nozzle closing direction which the head 35 of the command piston 9 receives gradually decreases. . As a result, as shown by the solid line in FIG. 2, the rising acceleration of the nozzle needle 4 is suppressed, and the fuel injection amount from the injection hole 15 can be suppressed, so that the initial injection rate of the injector 1 can be reduced.

2) When the control valve 2 is opened When the control valve 2 is closed by being electronically controlled by the ECU, a high pressure is introduced into the first control chamber 24 through the fuel supply / discharge passage 13 and the fuel passage 26. Fuel is supplied, and high-pressure fuel is supplied to the second control chamber 25 through the fuel supply / discharge passage 13 and the orifice 27. At this time, since the high-pressure fuel flows into the first control chamber 24 faster than the high-pressure fuel flows into the second control chamber 25, the internal pressure (P
1) rises more rapidly than the internal pressure (P2) of the second control chamber 25, so that the oil pressure in the nozzle closing direction received by the shoulder portion 34 of the command piston 9 rapidly increases. As a result, as shown by the solid line in FIG. 2, the time from when the control valve 2 is closed to when the nozzle needle 4 starts operating in the downward direction is reduced.

[Effects of the First Embodiment] As described above, the injector 1 of the present embodiment can reduce the initial injection rate. Since the generation of (NOx) can be reduced, the emission can be improved. Since the time from when the control valve 2 is opened to when the operation of the nozzle needle 4 in the valve opening direction is started can be shortened, the valve opening responsiveness of the nozzle needle 4 can be improved. Further, the control valve 2
Can be shortened from when the valve is closed to when the operation of the nozzle needle 4 in the valve closing direction is started, so that the valve closing response of the nozzle needle 4 can be improved.

When the pilot injection of a small amount of high-pressure fuel is performed before the main injection by opening the control valve 2 twice, from the end of the pilot injection to the start of the main injection. The minimum interval of can be expanded. Further, when fuel injection is performed continuously as in the above-described pilot injection, the injection interval can be shortened.

[Second Embodiment] FIG. 3 shows a second embodiment of the present invention and is a diagram showing a main structure of an injector.

In the injector 1 of this embodiment, a small diameter portion 31 having a smaller diameter than the large diameter portion 30 and slidable with respect to the orifice forming member 40 is provided at the upper end of the command piston 9 in the figure. Further, an annular plate-shaped orifice forming member 40 is fitted in the fitting portion 22 of the injector body 6.

The orifice forming member 40 corresponds to the partitioning portion of the present invention, and includes a first control chamber (fuel supply / discharge passage) 24 for applying oil pressure to the head 35 of the command piston 9 in the nozzle closing direction. A second control chamber 25 for applying a hydraulic pressure in the nozzle closing direction to the shoulder 34 of the command piston 9 is defined. The orifice forming member 40 has a sliding hole 41 for slidably supporting the head 35 of the command piston 9 and an orifice 42 on the outer peripheral side of the sliding hole 41.

In the injector 1 of this embodiment, the hydraulic pressure applied to the head 35 of the command piston 9 in the direction of closing the nozzle changes rapidly with the opening or closing of the control valve 2, and the command piston 9 The oil pressure applied to the shoulder 34 of the nozzle in the direction of closing the nozzle gradually changes.
The same effect as that of the embodiment can be achieved.

[Third Embodiment] FIG. 4 shows a third embodiment of the present invention and is a diagram showing a main structure of an injector.

The injector 1 of this embodiment has an axial hole 44 at the center of the head 43 of the command piston 9. Further, the injector 1 has an orifice forming member 46 fitted into the fitting portion 22 of the injector body 6 via a washer 45. This orifice forming member 46
Is a first control chamber 24 for applying an oil pressure in the nozzle closing direction to the end face of the head 43 of the command piston 9, and an axial hole 4 of the command piston 9.
4 and a second control chamber 25 for applying hydraulic pressure in the direction of closing the nozzle.

The orifice forming member 46 has a disk-shaped fitting portion 47 fitted into the fitting portion 22 and a cylindrical guide projecting from the center of the fitting portion 47 to the distal end side. It has a part 48. The fitted portion 47 includes the fuel supply / discharge passage 13 of the annular plate member 8 and the first control chamber 24.
And a plurality of fuel passages 49 that communicate with each other.

The guide portion 48 is a portion for guiding the command piston 9 in the vertical direction. The guide passage 48 communicates the fuel supply / discharge passage 13 of the annular plate member 8 with the second control chamber 25 at the axial center.
It has 0. At the end of the communication passage 50 on the second control chamber 25 side, an orifice 51 having a smaller passage cross-sectional area than the fuel passage 49 and narrowing the passage cross-sectional area of the communication passage 50 is provided.

In the injector 1 of this embodiment, the hydraulic pressure in the nozzle closing direction applied to the head 43 of the command piston 9 changes rapidly with the opening or closing of the control valve 2 and the command piston 9 The oil pressure applied to the bottom wall surface of the axial hole 44 in the nozzle closing direction gradually changes, whereby the same effect as that of the first embodiment can be achieved.

[Structure of Fourth Embodiment] FIGS. 5 and 6 show a fourth embodiment of the present invention, and FIG. 5A shows the main structure of a pressure accumulating fuel injection device for an internal combustion engine. FIG. 5
(B) is a diagram showing a main configuration of the injector.

The injector 1 of this embodiment includes a control valve 2 provided in the middle of a drain passage 11 and a nozzle body 3.
A nozzle needle 4 slidably supported therein, a cylinder 5 to which high-pressure fuel is supplied from a fuel supply passage 12 and a high-pressure fuel is discharged to a drain passage 11, and slidably supported in the cylinder 5. And a command piston 9.

The cylinder 5 of this embodiment comprises an injector main body 6, an orifice forming member 7, and an annular plate member 8. At the rear end of the injector body 6, FIG.
As shown in (b), a sliding part 21 and a fitting part 22 are formed. Note that the sliding portion 21 is provided with an annular groove forming an annular passage 52 communicating with the fuel supply passage 12.

At the center of the orifice forming member 7, an orifice (an outflow side fixing member according to the present invention) serving as an outflow side communication passage connecting the drain passage 11 formed in the annular plate member 8 and the control chamber 53 is provided. (Corresponding to an aperture) 54 is formed. The command piston 9 is formed with an inflow-side communication passage formed by a radial hole (hereinafter, referred to as an orifice: corresponding to the inflow-side fixed throttle) 55 and an axial hole 56. The inner diameters of the orifices 54 and 55 are substantially the same. The control chamber 53 is a space surrounded by the inner peripheral surface of the sliding portion 21, the illustrated lower end surface of the orifice forming member 7, and the head 57 of the command piston 9. This is a back pressure chamber that gives oil pressure in the valve direction.

The variable throttle 58 formed between the lower end of the annular passage 52 and the upper end of the orifice 55 corresponds to a passage cross-sectional area varying means of the present invention. Until the command piston 9 which rises and falls integrally with the nozzle needle 4 rises by a predetermined lift amount, the passage sectional area of the orifice 54 is made larger than the passage sectional area of the variable throttle 58. The variable throttle 58 has the smallest passage sectional area when the nozzle needle 4 is closed, and the passage sectional area does not change after the command piston 9 rises by a predetermined lift amount.

[Operation of Fourth Embodiment] Next, the operation of the injector 1 of this embodiment will be briefly described with reference to FIGS. Here, FIG. 6 is a time chart showing the injection rate of the injector. The broken line in FIG. 6 indicates the needle lift of the injector 200 of the second conventional example.

When the control valve 2 communicating with the fuel tank 10 is opened, the high-pressure fuel filled in the control chamber 53 starts flowing out through the orifice 54. At this time, FIG.
As shown in the figure, the outlet of the annular passage 52 and the orifice 5
5 has a small overlapping area with the inflow port, and a throttle (variable throttle 58) is formed between the annular passage 52 and the orifice 55. For this reason, from the fuel supply passage 12 to the annular passage 5
2. Variable throttle 58, orifice 55 and axial hole 56
, The flow of high-pressure fuel into the control chamber 53 is suppressed, so that the internal pressure in the control chamber 53 decreases rapidly.

That is, the oil pressure in the nozzle closing direction received by the head 57 of the command piston 9 due to the internal pressure of the control chamber 53 and the urging force in the nozzle closing direction by the coil spring 19 cause the nozzle needle 4 to move inside the oil reservoir 17. When the oil pressure in the nozzle opening direction received by the nozzle needle 4 is superior due to the pressure, the command piston 9 and the nozzle needle 4 start to rise as shown by the solid line in FIG. Thereby, fuel injection from the injection hole 15 is started.

Then, immediately after the start of the fuel injection, the control room 53
The internal pressure of the nozzle needle 4 continues to decrease rapidly, the nozzle needle 4 rises quickly, and a wide passage cross-sectional area is secured between the seat portion 18 of the nozzle needle 4 and the nozzle body 3. For this reason, the pressure loss in the seat portion 18 can be reduced, and the injection holes 1
The atomization of the high-pressure fuel injected from the nozzle 5 can be promoted.

As the nozzle needle 4 and the command piston 9 rise, the overlapping area between the outlet of the annular passage 52 and the inlet of the orifice 55 increases, that is, the passage cross-sectional area of the variable throttle 57 increases. The flow speed of the high-pressure fuel from the supply passage 12 into the control chamber 53 increases. Thereby, the internal pressure of the control chamber 53 starts to increase (the pressure drop speed decreases), and the rising speed of the nozzle needle 4 and the command piston 9 is suppressed.

When the nozzle needle 4 and the command piston 9 rise by a predetermined amount, the annular passage 5
The overlapping area between the outflow port 2 and the inflow port of the orifice 55 becomes the largest, and the high-pressure fuel flowing from the annular passage 52 flows into the control chamber 53 without being throttled. As a result, the rising speed of the nozzle needle 4 and the command piston 9 is further suppressed, so that the fuel injection amount from the injection hole 15 can be suppressed, and the injection rate is reduced.

[Effects of Fourth Embodiment] As described above, in the injector 1 of this embodiment, the nozzle needle 4 is rapidly raised immediately after the nozzle needle 4 is opened, and the nozzle needle 4 is raised by a predetermined amount. At the nozzle needle 4
Can be suppressed at a rising speed. Thus, an injection rate waveform as shown by the solid line in FIG. 6 can be obtained, so that promotion of atomization of the high-pressure fuel at the initial stage of injection and reduction of the initial injection rate of the injector 1 can both be achieved. Therefore,
Since generation of black smoke (smoke) and nitrogen oxides (NOx) can be suppressed, emission can be improved.

[Fifth Embodiment] FIG. 7 shows a fifth embodiment of the present invention and is a diagram showing a main structure of an injector.

The injector 1 of this embodiment is different from the fourth embodiment in that an orifice 55 on the fuel inflow side is formed in the injector body 6 and an annular groove forming an annular passage 52 is formed on the outer peripheral surface of the command piston 9. Only this point is different from the structure of the fourth embodiment. Thus, the injector 1 according to the present embodiment can also achieve the same operation and effect as the fourth embodiment.

[Structure of Sixth Embodiment] FIG. 8 shows a sixth embodiment of the present invention.
FIG. 8A is a diagram showing a main configuration of an accumulator type fuel injection device for an internal combustion engine, and FIG. 8B is a diagram showing a main configuration of an injector.

The injector 1 of this embodiment includes a control valve 2 provided in the middle of the drain passage 11 and a nozzle body 3.
A nozzle needle 4 slidably supported therein, and a cylinder 5 to which high-pressure fuel is supplied and discharged through a fuel supply and discharge passage 13
And a command piston 9 slidably supported in the cylinder 5. An orifice 14 is provided in the fuel supply passage 12 which connects the fuel supply / discharge passage 13 and the common rail.

The cylinder 5 of the present embodiment has a nozzle body 3
The injector body 6 is connected to a rear end face of the injector body 6 and an annular support member 61 connected to the rear end face of the injector body 6. At the rear end of the injector body 6, a cylindrical sliding portion 62 that slidably supports the outer peripheral surface of the command piston 9 is provided. A control chamber 63 is formed between the inner peripheral surface of the sliding portion 62, the front end surface of the support member 61, and the rear end surface of the command piston 9. Further, inside the support member 8, a round hole for forming the fuel supply / discharge passage 13 is formed while the inner peripheral surface slidably supports the outer peripheral surface of the command piston 9.

The command piston 9 of this embodiment has a cylindrical large-diameter portion 64 slidably supported on the inner peripheral surface of the sliding portion 62 and a slidably supported inner peripheral surface of the support member 61. And a small-diameter portion 65 to be formed. On the rear end face of the large diameter portion 64,
An annular shoulder 66 is formed on the command piston 9 to receive hydraulic pressure in the nozzle closing direction by the high pressure fuel in the control chamber 63. Further, the small diameter portion 65 is provided so as to have a smaller diameter than the large diameter portion 64 and to protrude rearward from the upper end surface of the large diameter portion 64 in the figure.

The small diameter portion 65 is provided in parallel with the first communication passage 67 for communicating the fuel supply / discharge passage 13 with the control chamber 63, and is provided in parallel with the first communication passage 67. 6
3 and a second communication passage 68 communicating with the second communication passage 3. The first communication passage 67 has an axial hole 69 provided in the axial direction of the small diameter portion 65, and an orifice 70 provided in a radial direction from a distal end of the axial hole 69. In addition,
The orifice 70 corresponds to the fixed throttle of the present invention, and the opening area to the control chamber 63 is always constant regardless of the elevation of the command piston 9.

The second communication passage 68 has an orifice 70
The cross-sectional area of the passage is larger than that of the small-diameter portion 65 and is formed by an axial groove 71 formed on the outer peripheral surface of the small-diameter portion 65. The variable throttle 72 formed by the tapered bottom wall surface of the axial groove 71 and the inner peripheral surface of the support member 61 constitutes a passage cross-sectional area variable means of the present invention.
That is, the variable throttle 72 (the axial groove 71) is provided so that the opening area to the control chamber 63 decreases as the command piston 9 rises. Therefore, the opening area of the axial groove 71 to the control chamber 63 becomes smaller than the opening area of the orifice 70 when the command piston 9 rises by a predetermined amount.

[Operation of Sixth Embodiment] Next, the operation of the injector 1 of this embodiment will be briefly described with reference to FIG.
When the control valve 2 communicating with the fuel tank 10 is opened, the high-pressure fuel filled in the control chamber 63 starts flowing out through the orifice 70 or the variable throttle 72. At this time, the opening area of the axial groove 71 constituting the variable throttle 72 (the cross-sectional area of the second communication passage 68) is larger than the opening area of the orifice 70 (the cross-sectional area of the first communication passage 67). Therefore, the high-pressure fuel in the control chamber 63 rapidly flows out through the variable throttle 72, that is, the second communication passage 68, so that the internal pressure in the control chamber 63 decreases rapidly.

The oil pressure in the nozzle closing direction received by the shoulder 66 of the command piston 9 due to the internal pressure of the control chamber 63 and the urging force in the nozzle closing direction by the coil spring 19 cause the nozzle needle 4 to close the oil reservoir 17. When the hydraulic pressure in the nozzle opening direction that the nozzle needle 4 receives due to the internal pressure prevails, the command piston 9 and the nozzle needle 4 start rising. Thereby, fuel injection from the injection hole 15 is started.

Then, as the nozzle needle 4 and the command piston 9 rise, the opening area of the axial groove 71 (passage cross-sectional area of the second communication passage 68) decreases, that is, the passage cross-sectional area of the variable throttle 72 decreases. By doing
The internal pressure of the control chamber 63 starts to increase (the pressure drop speed decreases), and the rising speed of the nozzle needle 4 and the command piston 9 is suppressed.

When the nozzle needle 4 and the command piston 9 rise by a predetermined amount, the axial groove 7
1 has the smallest opening area, and the high-pressure fuel in the control chamber 63 flows out through the orifice 70. As a result, the rising speed of the nozzle needle 4 and the command piston 9 is suppressed, so that the fuel injection amount from the injection hole 15 can be suppressed, and the injection rate is reduced.

[Effects of Sixth Embodiment] As described above, in the injector 1 of this embodiment, after the control valve 2 is opened, the shoulder 6 of the command piston 9 is actuated by the internal pressure of the control chamber 63.
Until the hydraulic pressure in the nozzle closing direction received by 6 and the urging force in the nozzle closing direction by the coil spring 19 are superior to the hydraulic pressure in the nozzle opening direction received by the nozzle needle 4 due to the internal pressure of the oil reservoir 17 by the nozzle needle 4 time of,
That is, the nozzle needle 4 and the command piston 9
The time required for the nozzle needle 4 to start rising can be reduced, and the valve opening responsiveness of the nozzle needle 4 can be improved. Therefore, a wide passage cross-sectional area is secured between the seat portion 18 of the nozzle needle 4 and the nozzle body 3. Therefore, the pressure loss in the seat portion 18 can be reduced, and the atomization of the high-pressure fuel injected from the injection holes 15 can be promoted.

Further, as the command piston 9 rises, the outflow of high-pressure fuel from the second communication passage 68 decreases, and the control chamber 6
Since the falling speed of the internal pressure of the nozzle 3 can be suppressed, that is, the rising speed of the nozzle needle 4 can be suppressed, the initial injection rate of the injector 1 can be reduced.
Therefore, black smoke (smoke) and nitrogen oxides (NO
Since the generation of x) can be suppressed, the emission can be improved.

[Seventh Embodiment] FIG. 9 shows a seventh embodiment of the present invention and is a diagram showing a main structure of an injector.

The cylinder 5 of the present embodiment has a nozzle body 3
Injector body 6 connected to the rear end face, fitted member 73 having a T-shaped cross section fitted into the rear end of injector body 6, and an annular shape connected to the rear end face of injector body 6. And the supporting member 61 of the above.

The fitted member 73 includes an annular portion, and a tubular portion (guide portion) projecting from the center of the annular portion toward the distal end, and has an axial hole 74 penetrating the axis, and It has an orifice 75 provided in the radial direction of the axial hole 74. The orifice 75 corresponds to the fixed restrictor of the present invention, and the opening area (passage cross-sectional area) to the control chamber 76 is always constant regardless of the elevation of the command piston 9. The outer peripheral surface of the fitted member 73 is
An inner circumferential surface of the command piston 9 is slidably supported, and an axial groove 77 is formed on an outer circumferential surface thereof. The control chamber 76 is a back pressure chamber that applies a hydraulic pressure in the nozzle closing direction to the head 78 of the command piston 9.

The command piston 9 of this embodiment has an axial hole 79 on the upper end surface (head 78) in the figure, and the outer peripheral surface is slidably supported on the inner peripheral surface of the sliding portion 81 of the injector body 6. The inner peripheral surface is slidably supported on the outer peripheral surface of the tubular portion of the fitted member 73. Between the inlet wall of the axial hole 79 of the command piston 9 and the tapered bottom wall of the axial groove 77 of the fitted member 73, there is provided a variable throttle 80 constituting the passage cross-sectional area variable means of the present invention. Provided. That is, the variable throttle 80 (the axial groove 77) is provided so that the opening area to the control chamber 76 is reduced as the command piston 9 is raised.

The axial groove 77 may be provided on the inner peripheral surface of the axial hole 79. The orifice 75 corresponds to the first communication passage of the present invention, and connects the fuel supply / discharge passage 13 and the control chamber 76 via the axial hole 74. In addition, a fuel passage 81 formed between the inlet wall of the axial hole 79 of the command piston 9 and the axial groove 77 of the fitted member 73.
Corresponds to the second communication passage of the present invention,
The fuel supply / discharge passage 13 communicates with the control chamber 76 via the hole 4 and the axial hole 79. With the above configuration, the injector 1 of the present embodiment can achieve the same operation and effect as the injector 1 of the sixth embodiment.

[Eighth Embodiment] FIG. 10 shows an eighth embodiment of the present invention. FIG. 10 (a) is a diagram showing a main structure of a pressure accumulating fuel injection device for an internal combustion engine. (B) is a diagram showing a main configuration of the injector.

The injector 1 of this embodiment includes a control valve 2 provided in the middle of a drain passage 11 and a nozzle body 3.
A nozzle needle 4 slidably supported therein, a cylinder 5 to which high-pressure fuel is supplied from a fuel supply passage 12 and a high-pressure fuel is discharged to a drain passage 11, and slidably supported in the cylinder 5. And a command piston 9.

The difference from the injector 1 of the sixth embodiment is that the injector 1 has an inflow-side communication passage through which high-pressure fuel flows into the control chamber 63 and an outflow-side communication passage through which high-pressure fuel flows out of the control chamber 63. That is, the inflow-side communication path forms a first communication path 84 having an orifice 83. Further, the outflow side communication passage is the second communication passage described in the sixth embodiment.
In the communication passage 68, the second communication passage 68 has an axial groove 71 (variable throttle 72). With the above configuration, the injector 1 of the present embodiment is different from the injector 1 of the sixth embodiment.
The same operation and effect as described above can be achieved.

[Modification] In the first embodiment, the orifice 27 penetrating the orifice forming member 7 is provided as a fixed throttle that communicates the fuel supply / discharge passage 13 with the second control chamber 25. May be provided with a communication passage having a passage cross-sectional area equivalent to that of the fuel passage 26, and a fixed throttle for reducing the passage cross-sectional area may be provided in a part of the communication passage. Further, the inner diameter of the orifice 27 is changed from the side of the fuel supply / discharge passage 13 to the second control chamber 25.
The diameter may be the same across the sides. The orifice 14 provided in the fuel supply passage 12 may be replaced with an electromagnetic on-off valve that closes when the control valve 2 is open and opens when the control valve 2 is closed.

In the second embodiment, an orifice 42 communicating between the first control chamber 24 and the second control chamber 25 is used as a fixed throttle.
However, a communication path for communicating the first control chamber 24 with the second control chamber 25 may be provided, and a fixed throttle for reducing the passage cross-sectional area may be provided in a part of the communication path. Further, the shape of the orifice 42 may be tapered such that the inner diameter gradually decreases from the first control chamber 24 side to the second control chamber 25 side.

In the third embodiment, the communication passage 50 having the orifice 51 at the end of the second control chamber 25 is used as the communication passage. However, the communication passage is provided from the fuel supply / discharge passage 13 side to the second control chamber. A fixed aperture may be provided over the 25th side. Alternatively, the shape of the orifice 51 may be tapered such that the inner diameter gradually decreases from the fuel supply / discharge passage 13 toward the second control chamber 25.

In the fourth and fifth embodiments, the inflow side communication path is
The entire outlet-side communication passage is constituted only by the orifice 54, but the inflow-side communication passage is constituted by the variable throttle 5 and the annular passage 52, the variable throttle 58, the orifice 55, and the axial hole 56.
8 and a fixed throttle may be partially provided in the middle of the outflow side communication passage. Alternatively, the orifices 54, 55 may be tapered so that the inner diameter gradually decreases toward the downstream side in the flow direction of the high-pressure fuel.

In the sixth embodiment, as the first communication passage, the first communication passage 67 including the axial hole 69 and the orifice 70 is used.
However, the entire first communication path may be a fixed throttle.
Further, the shape of the orifice 70 may be tapered such that the inner diameter gradually decreases from the axial hole 69 toward the control chamber 63. In the sixth embodiment, the axial groove 71 is provided on the outer peripheral surface of the small diameter portion 65 of the command piston 9, and the second communication passage 68 is formed between the command piston 9 and the inner peripheral surface of the support member 61. An axial groove may be provided on the inner peripheral surface of 61 to form a second communication passage 68 between the command piston 9 and the outer peripheral surface of the small diameter portion 65.

In the seventh embodiment, the orifice 75 is provided in the entire first communication passage. However, a fixed throttle may be provided in a part of the first communication passage. Alternatively, the shape of the orifice 75 may be tapered such that the inner diameter gradually decreases from the axial hole 74 toward the control chamber 76. In the seventh embodiment, an axial groove 77 is provided on the outer peripheral surface of the tubular portion of the fitted member 73,
Although the fuel passage (second communication passage) 81 is formed between the command piston 9 and the inlet wall of the axial hole 79, an axial groove is provided on the inner peripheral surface of the command piston 9, and the fitted member 73 is formed.
A second communication path may be formed between the outer peripheral surface and the outer peripheral surface.

In the eighth embodiment, the inflow-side communication passage (first communication passage) provided with the orifice 83 in the middle is used.
The entire communication passage may be a fixed throttle. Further, the shape of the orifice 70 may be tapered such that the inner diameter gradually decreases from the axial hole 69 toward the control chamber 63. In the eighth embodiment, the axial groove 71 is provided on the outer peripheral surface of the small diameter portion 65 of the command piston 9, and the second communication passage 68 is formed between the command piston 9 and the inner peripheral surface of the support member 61. An axial groove is provided on the inner peripheral surface of the command piston 61 so that the small diameter portion 6 of the command piston 9 is formed.
The second communication passage 68 may be formed between the second communication passage 68 and the outer peripheral surface of the fifth communication passage 5.

In the first to eighth embodiments, the control valve (two-way solenoid valve) 2 is used as the on-off valve, but a three-way solenoid valve may be used as the on-off valve.

[Brief description of the drawings]

FIG. 1A is a schematic diagram illustrating a main configuration of a pressure accumulating fuel injection device for an internal combustion engine, and FIG. 1B is a cross-sectional view illustrating a main configuration of an injector (first embodiment).

FIG. 2 is a graph showing a relationship between an opening / closing state of a control valve and a needle lift (first embodiment).

FIG. 3 is a cross-sectional view showing a main configuration of an injector (second embodiment).

FIG. 4 is a cross-sectional view showing a main configuration of an injector (third embodiment).

FIG. 5A is a schematic diagram illustrating a main configuration of a pressure accumulating fuel injection device for an internal combustion engine, and FIG. 5B is a cross-sectional view illustrating a main configuration of an injector (fourth embodiment).

FIG. 6 is a time chart showing an injection rate of an injector (fourth embodiment).

FIG. 7 is a sectional view showing a main configuration of an injector (fifth embodiment).

FIG. 8A is a schematic diagram showing a main configuration of a pressure accumulating fuel injection device for an internal combustion engine, and FIG. 8B is a cross-sectional view showing a main configuration of an injector (sixth embodiment).

FIG. 9 is a sectional view showing a main configuration of an injector (seventh embodiment).

FIG. 10A is a schematic diagram illustrating a main configuration of a pressure accumulating fuel injection device for an internal combustion engine, and FIG. 10B is a cross-sectional view illustrating a main configuration of an injector (eighth embodiment).

11A is a schematic diagram showing a main configuration of a pressure accumulating fuel injection device for an internal combustion engine, and FIG. 11B is a cross-sectional view showing a main configuration of an injector (first conventional example).

12A is a schematic diagram showing a main configuration of a pressure accumulating fuel injection device for an internal combustion engine, and FIG. 12B is a cross-sectional view showing a main configuration of an injector (second conventional example).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injector (fuel injection valve) 2 Control valve (open / close valve) 3 Nozzle body 4 Nozzle needle 5 Cylinder 6 Injector main body 7 Orifice forming member (partition part) 8 Annular plate member 9 Command piston 10 Fuel tank 11 Drain passage (fuel discharge passage) 12) fuel supply passage 13 fuel supply / discharge passage 15 injection hole 17 oil reservoir 24 first control chamber 25 second control chamber 27 orifice (communication passage, fixed throttle) 30 large diameter portion 31 small diameter portion 33 pin portion 34 shoulder portion 35 head Part 41 Sliding hole 52 Annular passage 53 Control chamber 54 Orifice (outflow-side communication passage, outflow-side fixed throttle) 55 Orifice (inflow-side communication passage, inflow-side fixed throttle) 56 Axial hole (inflow-side communication passage) 58 Variable throttle (Path section variable means) 63 Control room 67 First communication path 68 Second communication path 71 Axial groove 72 Variable throttle Passage sectional area varying means) 75 Orifice (fixed throttle, the first communication passage) 80 variable restrictor (passage cross-sectional area varying means) 81 fuel passage (second communication passage) 84 first communication passage

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 61/10 F02M 61/10 F

Claims (8)

[Claims] (A) A fuel supply / discharge passage communicating with both a fuel supply passage for supplying high-pressure fuel from a fuel accumulator for accumulating high-pressure fuel and a fuel discharge passage for discharging high-pressure fuel. (B) an on-off valve for opening and closing the fuel discharge passage; and (c) a nozzle body having an oil sump in which high-pressure fuel is always introduced from the fuel accumulator and an injection hole for injecting fuel into the internal combustion engine. d) a nozzle needle whose front end faces the oil reservoir and opens and closes the injection hole; and (e) a piston having one end connected to the other end of the nozzle needle and displaced integrally with the nozzle needle; (F) A control chamber communicating with the fuel supply / discharge passage is formed between the control chamber and the other end of the piston.
A cylinder having a partition section partitioned into a first control chamber for applying a pressure in a valve closing direction to a part of the piston and a second control chamber for applying a pressure in a valve closing direction to the rest of the piston; g) A fuel injection valve provided in a communication passage communicating the fuel supply / discharge passage with the second control chamber, and having a fixed throttle for reducing a passage cross-sectional area of the communication passage. 2. The fuel injection valve according to claim 1, wherein a sliding hole for slidably supporting a part of the cylinder is provided at a central portion of the partition, and the sliding hole is provided at a central portion of the partition. The fixed throttle is provided in the outer peripheral side of the partition, one end face of the partition faces the first control chamber integrated with the fuel supply / discharge passage, and the other end face of the partition is A fuel injection valve facing a second control chamber, wherein the fixed throttle communicates the first control chamber with the second control chamber. 3. The fuel injection valve according to claim 1, wherein pilot injection is performed before main injection for injecting high-pressure fuel into the internal combustion engine. (A) a fuel supply passage for supplying high-pressure fuel from a fuel accumulator for accumulating high-pressure fuel; (b) a fuel discharge passage for discharging high-pressure fuel; An on-off valve for opening and closing a fuel discharge passage; (d) an oil reservoir in which high-pressure fuel is always introduced from the fuel accumulator, and a nozzle body having an injection hole for injecting fuel into an internal combustion engine; (F) a nozzle needle that opens and closes the injection hole facing the oil reservoir; (f) a piston having one end connected to the other end of the nozzle needle and displaced integrally with the nozzle needle; When high-pressure fuel is introduced from the fuel supply passage to the other end, the pressure in the valve closing direction applied to the piston increases, and when high-pressure fuel is discharged to the fuel discharge passage, the pressure is applied to the piston. Valve closing (H) an inflow-side communication passage that connects the fuel supply passage and the control chamber; and (i) a communication between the fuel discharge passage and the control chamber. (J) the outflow side communication passage is displaced integrally with the nozzle needle, and the outflow side communication passage is smaller than the passage cross-sectional area of the inflow side communication passage until the nozzle needle is displaced in a valve opening direction by a predetermined displacement amount. A fuel injection valve comprising: a passage cross section variable means for increasing a passage cross section of the side communication passage. 5. The fuel injection valve according to claim 4, wherein the inflow-side communication passage has an inflow-side fixed throttle for narrowing a passage cross-sectional area, and the outflow-side communication passage narrows a passage cross-sectional area. Fuel injection valve having an outflow-side fixed throttle for use in the fuel injection valve. 6. A fuel supply / discharge passage communicating with both a fuel supply passage for supplying high pressure fuel from a fuel pressure accumulator for accumulating high pressure fuel and a fuel discharge passage for discharging high pressure fuel. (B) an on-off valve for opening and closing the fuel discharge passage; and (c) a nozzle body having an oil sump in which high-pressure fuel is always introduced from the fuel accumulator and an injection hole for injecting fuel into the internal combustion engine. d) a nozzle needle whose front end faces the oil reservoir and opens and closes the injection hole; and (e) a piston having one end connected to the other end of the nozzle needle and integrally displaced with the nozzle needle; (F) a cylinder forming a control chamber between the other end of the piston, through which high-pressure fuel is introduced from the fuel supply passage and high-pressure fuel being discharged into the fuel discharge passage; and (g) the fuel. Supply and discharge The communicating the road and the control chamber 1
(H) a second communication passage provided in parallel with the first communication passage and communicating the fuel supply / discharge passage with the control chamber; and (i) displaced integrally with the nozzle needle. Until the nozzle needle rises by a predetermined amount in the valve opening direction, the second cross-sectional area of the first communication path is smaller than the second cross-sectional area.
A fuel injection valve comprising: a passage cross section variable means for increasing a passage cross section of a communication passage. 7. The fuel injection valve according to claim 6, wherein the first communication passage has a fixed throttle for reducing a cross-sectional area of the passage. 8. One of claims 1 to 7
3. The fuel injection valve according to claim 1, further comprising valve opening pressure determining means for urging the nozzle needle in a valve closing direction and determining a valve opening pressure of the nozzle needle.