JPH1122584A - Fuel injection device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To control the fuel injection rate inexpensively according to the driving situation. SOLUTION: Fuel stored in a fuel storage chamber 32 is introduced into a control chamber, a valve body is pushed by the pressure of the high-pressure fuel introduced into the control chamber, a fuel injection hole is closed, and the high-pressure fuel in the control chamber is discharged. The fuel injection valve which opens the fuel injection hole by lowering the pressing force of the valve body by discharging from the discharge path is driven by the pressure of the fuel discharged from the control chamber into the fuel discharge path, and the fuel is driven according to the drive. A fuel outflow variable control means 43 for varying the passage cross-sectional area of the discharge passage is provided. In the initial stage of fuel injection, the fuel outflow variable control means 43 is utilized by utilizing the high pressure of the fuel flowing out of the control chamber. Thus, the passage cross-sectional area of the fuel discharge passage is reduced, the lift speed of the valve element driven by the control chamber pressure is reduced, the fuel injection rate is reduced, and thereafter, the pressure of the fuel flowing out of the control chamber is reduced. Taking advantage of becoming In the fuel outflow variable control means 43,
The cross-sectional area of the fuel discharge passage is increased, the pressure in the control chamber is rapidly reduced, the lift speed of the valve body is increased, and the fuel injection rate is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device, and more particularly, to an accumulator type fuel injection device used for a diesel engine.

[0002]

2. Description of the Related Art In general, a pressure accumulating type (common rail type) fuel injection device introduces high pressure fuel supplied from a pressure accumulating chamber into a control chamber provided inside a fuel injection valve, and a needle valve of a fuel control valve. , The needle valve is kept in a normally closed state, the fuel in the control chamber is leaked to the fuel discharge path, and the control chamber is depressurized to raise the needle valve. In this configuration, fuel is injected from the hole.

In such a conventional fuel injection device, the fuel injection rate depends on the valve opening at the tip of the needle valve and the size of the valve hole. That is, in the process of opening the flow path to the fuel injection hole by raising the needle valve, while the flow path area is smaller than the fuel injection hole, the fuel injection rate is regulated by the flow path area, and After the flow passage area becomes larger than the cross-sectional area of the fuel injection hole, the fuel injection rate is defined by the cross-sectional area of the fuel injection hole.

[0004]

In the common rail system,
Since fuel is supplied in a high pressure state, an unnecessary amount of fuel is injected from the beginning of injection. In order to improve the engine performance, it is originally desired to advance the fuel injection timing and to advance the fuel injection timing. However, if the fuel injection amount in the initial stage of the fuel injection is too large, excessive combustion noise due to rapid combustion in the initial stage of the combustion will be accompanied. . Therefore, in the early stage of the fuel injection control, it is necessary to advance the angle by lowering the injection rate and suppressing the injection amount, thereby suppressing the initial combustion and reducing the combustion noise. On the other hand, since the injection must be completed in a short period of time, it is necessary to increase the fuel injection rate after the middle stage of the injection.

[0005] In response to such a demand, in the above-mentioned conventional example,
Since the fuel injection rate pattern is determined by the cross-sectional area of the flow path to the fuel injection hole and the cross-sectional area of the fuel injection hole, the fuel injection rate cannot be changed without flexibility.

Japanese Patent Laid-Open Publication No. Hei 5-71438 proposes a fuel injection device that controls the injection rate to be low at the beginning of fuel injection and high at the end of fuel injection. In this device, the pressure in a control chamber that holds a back pressure acting on a nozzle needle that opens and closes a fuel injection hole of a fuel injection valve is switched by a switching valve to a high-pressure chamber on a fuel supply path side and a fuel return path (fuel discharge path). In a fuel injection device that controls switching to a low-pressure chamber that is a (road) side to inject fuel from the fuel injection holes, the fuel injection device is disposed in series with the low-pressure side of the switching valve, and controls the flow of fuel on the low-pressure side. A control valve that takes at least three states of a first state in which shutoff is performed, a second state in which a part of the low-pressure side fuel is released, and a third state in which the low-pressure side fuel is completely released; At the time of non-injection, the switching valve is set to the high pressure side and the control valve is set to the first state. At the beginning of the injection, the switching valve is switched to the low pressure side, and at the same time, the control valve is set to the second state. With the valve switched to the low pressure side In a configuration in which a control device for the control valve and the third state.

Here, the control valve described in the publication is a spool valve driven by applying a voltage to a piezo element. The relationship between the fuel injection time and the injection amount determined according to the fuel pressure (fuel supply pressure) is stored in the form of a map in advance, and a detection signal of the fuel pressure in the fuel storage chamber is sent to the control device. By being input, the control device controls the switching valve and the spool valve according to the fuel pressure, and switches the switching valve to the low pressure side at the initial stage of the injection, and at the same time, sets the control valve to the second state, thereby setting the fuel discharging path. The discharge flow rate is made smaller than it should be, whereby the pressure in the control chamber is slightly released, and the nozzle needle is slightly raised to lower the fuel injection rate from the fuel injection hole. Then, by setting the third state, the pressure in the control chamber is completely released, the nozzle needle is completely raised, and a high injection rate is achieved.

However, such an apparatus requires a driving source (power supply) such as a piezo element, a map for controlling the driving source, and the like, resulting in an increase in cost. In view of the foregoing, an object of the present invention is to provide a technique for controlling the fuel injection rate with a valve provided in a fuel discharge path to vary the fuel injection rate according to the fuel injection timing at a low cost. I do.

[0009]

The present invention adopts the following means in order to solve the above-mentioned problems. That is, the fuel injection device of the present invention introduces a fuel pressure accumulating chamber that accumulates fuel, and high-pressure fuel accumulated in the fuel accumulating chamber into a control chamber, and operates the valve body with the pressure of the high-pressure fuel introduced into the control chamber. A fuel injection valve that presses the fuel injection hole to close the fuel injection hole, discharges high-pressure fuel in the control chamber from the fuel discharge path, and opens the fuel injection hole by reducing the pressing force of the valve body. And a fuel outflow variable control means that is provided on the passage and is driven by the pressure of the fuel discharged from the control chamber, and that varies the passage cross-sectional area of the fuel discharge passage according to the drive.

Here, the fuel outflow variable control means includes:
For example, when the pressure of the fuel flowing out of the control chamber is high, the passage area is reduced, and when the pressure is low, the cross-sectional area of the passage is increased.

The fuel injection valve includes a fuel injection hole,
A valve element for closing the fuel injection hole, an urging means for urging the valve element in a normally closed direction, and a first fuel for guiding high-pressure fuel supplied at a predetermined pressure from a fuel supply source to the fuel injection hole A supply path, a fuel reservoir for receiving fuel supplied from the first fuel supply path and applying fuel pressure to the valve body in a valve opening direction, and receiving high-pressure fuel supplied at a predetermined pressure from a fuel supply source. A control chamber that presses the valve body in the normally closed direction, a fuel discharge path that discharges high-pressure fuel in the control chamber to reduce the hydraulic pressure in the control chamber, and a fuel discharge path from the control chamber, and controls when closed. It is common to have a back pressure control valve that contains high-pressure fuel in the chamber and allows the fuel to escape from the control chamber to the fuel discharge path when opened.

In such a fuel injection valve, when the back pressure control valve is closed, the fuel pressure applied to the control chamber increases. At that time, the pressing force received by the valve body from the fuel pressure in the control chamber is represented by Fm. If the pressing force received by the valve element from the fuel pressure in the fuel reservoir is Fs, and the urging force of the urging means is Fc, Fm
+ Fc> Fs and Fc <Fs, and the fuel injection hole is closed by the valve element. On the other hand, when the back pressure control valve is opened and the fuel is released from the control chamber to the fuel discharge path, the fuel pressure in the control chamber decreases, so that when Fm + Fc <Fs,
The valve body lifts against the urging force of the urging means, the fuel injection hole is opened, and fuel injection is started.

The fact that the fuel outflow variable control means is driven by the pressure of the fuel flowing out of the control chamber eliminates the need for a drive power supply required for the above-described conventional spool valve using a piezo element. This means that a map for use is unnecessary. In the present fuel injection valve, high-pressure fuel flows out of the fuel discharge passage from the control chamber, and the pressure in the control chamber becomes low, the valve body lifts, and the fuel injection hole is opened, so that fuel injection is started. .

In the early stage of fuel injection, the pressure of the fuel flowing out is still high, so the fuel outflow variable control means reduces the cross-sectional area of the fuel discharge passage in accordance with the high fuel pressure. A small passage cross-sectional area means that the flow rate resistance is large and the pressure in the control chamber does not readily decrease, so that the lift speed of the valve body is slow and the lift amount is small. Therefore, the fuel injection rate is controlled to be low at the beginning of the fuel injection.

Thereafter, in the later stage of the fuel injection, the fuel pressure in the control chamber gradually decreases, so that the fuel outflow variable control means increases the passage sectional area of the fuel discharge passage in accordance with the low fuel pressure. Then, the amount of fuel flowing out from the control chamber through the fuel discharge path increases, so that the fuel pressure in the control chamber rapidly decreases, the lift speed of the valve body of the fuel injection valve increases, and the lift amount of the valve body decreases. As the size increases, the fuel injection rate increases.

In the present invention, more preferably, an inlet orifice for determining a fuel supply amount into the control chamber is provided in a fuel supply passage to the control room, while a fuel discharge passage from the control room is provided in the fuel discharge passage. The outlet cross-sectional area of the outlet orifice is set to be larger than the cross-sectional area of the inlet orifice, and the fuel outflow variable control means is provided when the fuel pressure in the control chamber is high. The cross-sectional area of the outlet orifice is made equal to the cross-sectional area of the inlet orifice, and when the fuel pressure in the accumulator becomes low, the cross-sectional area of the outlet orifice is made larger than the cross-sectional area of the inlet orifice. Is preferred.

More philosophically, the passage cross-sectional area of the fuel discharge passage from the control chamber is set to be larger than the passage cross-sectional area of the fuel supply passage to the control chamber. When the pressure of the fuel flowing out of the chamber is high, the cross-sectional area of the fuel discharge passage is equal to the cross-sectional area of the fuel supply passage, and when the pressure of the fuel flowing out of the control chamber becomes low, The cross-sectional area of the passage is made larger than the cross-sectional area of the fuel supply passage.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described.
This will be described with reference to the drawings.

<Overall Configuration of Apparatus> FIG. 1 shows the overall configuration of a fuel injection device. This device pumps up fuel from a fuel tank 1 as a fuel supply source and sends it out at a predetermined pressure, and a fuel pump 2 (rotary supply pump). A fuel pressure accumulating chamber 3 for accumulating pressure is provided.

A plurality of fuel supply paths 4 are connected to the fuel pressure accumulating chamber 3, and a plurality of fuel injection valves 5 attached to the internal combustion engine are connected to each fuel supply path 4. When the internal combustion engine is, for example, six cylinders and each cylinder is provided with one fuel injection valve 5, the number of fuel supply passages 4 and the number of fuel injection valves 5 are each six.

A fuel pressure sensor 6 is provided in the fuel accumulator 3 so as to detect the fuel pressure in the fuel accumulator 3. Further, the fuel pressure sensor 6 is connected to a control device 7 composed of a computer.

The control device 7 includes an accelerator sensor S1 for detecting whether the accelerator pedal is depressed or not.
An intake pressure sensor S2 for detecting an intake pressure to the internal combustion engine, a water temperature sensor S3 for detecting a temperature of cooling water of the internal combustion engine, an engine speed sensor (NE sensor) S4 for detecting a rotation speed of the internal combustion engine, An aero flow meter S5 for detecting an air intake amount, a G sensor S6 for detecting an inertial force applied to the vehicle, and various sensors required for vehicle control are connected.

The control device 7 is provided with a fuel pump drive control unit 8 and a fuel injection valve drive control unit 9 which operate according to operating conditions determined based on information from the various sensors. 2 and the fuel injection valve 5 are drive-controlled.

The control device 7 performs feedback control of the fuel pressure in the fuel storage chamber 3 so as to reach a preset target pressure for steady operation. That is, the fuel pressure sensor 6
The drive signal is sent to the fuel pump 2 until the detected pressure from the target reaches the target pressure, the supply of fuel is continued, and when the target pressure is reached, the control of stopping the driving of the fuel pump 2 is repeated.

When the pressure in the fuel accumulator chamber 3 reaches a predetermined set pressure exceeding the target pressure, the pressure in the fuel accumulator chamber 3 is released. An escape relief valve 11 is provided. The relief valve 11 is provided so as to be interposed in a fuel release path 12 connected to the fuel supply source side, that is, the fuel tank 1.

<Fuel Injection Valve> As shown in FIG. 2, the fuel injection valve 5 is provided with a cylindrical main body 22 having a fuel injection hole 21 at the tip, and is provided inside the cylindrical main body 22 so as to be movable forward and backward. A needle-shaped needle valve 23 (valve element) that closes the fuel injection hole 21 at the time of advance and opens the fuel injection hole 21 at the time of retreat, and a coil as urging means for urging the needle valve 23 in the closing direction. And a spring 24.

Further, the fuel injection valve 5 receives a high-pressure fuel from a first fuel supply passage 31 that guides high-pressure fuel supplied from the pressure storage chamber 3 as a fuel supply source at a predetermined pressure to the fuel injection hole 21. A control chamber 32 for pressing the needle valve 23 in the closing direction, and a high-pressure fuel branched from the first fuel supply passage 31 and supplied at a predetermined pressure from a pressure storage chamber serving as a fuel supply source to the control chamber 32. A second fuel supply path 33 leading to the control chamber 3 and a high-pressure fuel in the control chamber 32 are discharged to control the control chamber 3.
And a fuel discharge passage 34 for lowering the fluid pressure in the fuel cell 2.

The second fuel supply path 33 is provided with an inlet orifice 33a for determining the amount of fuel flowing into the control chamber 32, while the fuel discharge path 34 is provided with an outlet orifice 34a for determining the amount of fuel discharged. Is provided. The ratio of the passage sectional area of the inlet orifice 33a to that of the outlet orifice 34a is, for example,
Outlet orifice 34a, such as 2: 3
Is set larger than the inlet orifice 33a.

The needle valve 23 has a main piston 23a which faces the control chamber 32 and lowers the needle valve 23 by receiving fuel pressure in the control chamber 32. On the fuel injection hole 21 side of the needle valve 23, a sub piston 23c is provided. A fuel reservoir 31a is provided in the middle of the first fuel supply passage 31 leading to the fuel injection hole 21 so as to face the sub piston 23c. Therefore, the fuel pressure in the fuel reservoir 31a is applied to the sub piston 23c,
The needle valve 23 is pushed in the opening direction (upward in the figure).
The pressure receiving area Ss in which the sub piston 23c receives the fuel pressure in the fuel reservoir 31a is equal to the main piston 23
a is set smaller than the pressure receiving area Sm for receiving the fuel pressure in the control chamber 32. Further, the coil spring 24 for urging the needle valve 23 in the valve closing direction is disposed on the side of the main piston 23a of the sub piston 23c.

The main piston 23a is connected to the control chamber 32
When the pressing force received from the fuel pressure in the fuel tank is Fm, the pressing force received by the sub-piston 23c from the fuel pressure in the fuel reservoir 31a is Fs, and the urging force of the coil spring 24 is Fc, Fm + Fc> Fs, Fc <Fs.

Further, a fuel discharge passage 34 from the control chamber 32
When closed, high-pressure fuel is contained in the control chamber 32,
A normally closed back pressure control valve 35 is provided to allow fuel to escape from the control chamber 32 to the fuel discharge passage 34 when opened. The back pressure control valve 35 is formed by an electromagnetic valve, and is provided in the tubular main body 22. When the back pressure control valve 35 is closed, the fuel pressure applied to the control chamber 32 increases, and the main piston 23a is pushed by the pressure, and the urging force of the spring 24 is also applied thereto. The needle valve 23 descends.

At this time, the fuel having the same pressure as that applied to the control chamber 32 is introduced from the first fuel supply passage 31 into the fuel reservoir 31a and presses the sub piston 23c. The pressing force Fs is Fm + Fc. Therefore, the needle valve 23 is kept in a state where the fuel injection hole 21 is closed.

Thereafter, when the back pressure control valve 35 is opened, fuel in the control chamber 32 is discharged from the fuel discharge passage 34. At this time, since the outlet orifice 34a is set larger than the inlet orifice 33a, Room 3
The amount of fuel flowing out of the control chamber becomes larger than the amount of fuel flowing into the fuel cell 2, and as a result, the fuel pressure in the control chamber 32 decreases.

When Fm + Fc <Fs, the needle valve 23 is lifted against the urging force of the spring 24, the fuel injection hole 21 is opened, and fuel injection is started. Next, the relationship between the fuel injection hole 21 and the needle valve 23 is shown in the detailed view of FIG. The inner wall of the fuel injection hole 21 forming the valve seat is formed in a tapered shape.
The tip of the needle valve 23 also has a tapered conical shape. Due to such a shape, when the passage area Sp formed when the needle valve 23 lifts and separates from the inner wall surface serving as the valve seat is smaller than the cross-sectional area Sf of the fuel injection hole 21, the fuel passage area is determined by the passage area. After the injection rate is determined and the needle valve 23 is further lifted and the passage area Sp becomes larger than the cross-sectional area of the fuel injection hole 21, the fuel injection hole 21
Determines the fuel injection rate.

<Fuel outflow variable control means> In addition to the above configuration, if a variable valve 43 (fuel outflow variable control means) for varying the amount of fuel flowing out of the control chamber 32 is provided, the lift of the needle valve 23 is increased. Speed control becomes possible.

The variable valve 43 has a valve chamber 51 interposed in the fuel discharge passage 34, and a piston 52 provided in the valve chamber 51 so as to be able to advance and retreat, and driven by receiving fuel from the control chamber 32. doing. The inlet to the return passage 34b that returns from the valve chamber 51 to the fuel tank is the outlet orifice 34a described above, and is formed so that the cross-sectional area of the passage can be varied by the advance and retreat of the piston 52. That is, a communication passage 52a connecting the control chamber 32 side and the return passage side is formed in the piston 52, and an opening edge of the communication passage 52a is formed by the return passage 34b.
The cross-sectional area of the passage is adjusted to be large or small between the opening orifice 34a, which is the entrance to the opening, and the opening edge of the opening.

The cross-sectional area of the communication passage is equal to or larger than the cross-sectional area of the outlet orifice 34a. Further, a spring 53 is provided in the valve chamber 51 for urging the piston 52 and positioning the piston 52 in a direction in which the passage cross-sectional area of the fuel discharge passage 34 (the passage cross-sectional area of the outlet orifice 34a) generally increases. ing. From the control chamber 32 through the fuel discharge passage 34, the valve chamber 5
When the outflow fuel is introduced into the cylinder 1, the piston 52 moves by receiving the fuel pressure, and the passage cross-sectional area of the fuel discharge passage 34 (the passage cross-sectional area of the outlet orifice 34a) is reduced.

<Fuel Injection Valve Driving Control> The fuel injection valve driving control is performed by the fuel injection valve driving control unit 9. In a diesel engine, fuel injection is performed at a predetermined crank angle of the engine during a compression stroke to an expansion stroke, for example, 1 before top dead center.
Perform a predetermined amount from 0 ° CA (crank angle) to 5 ° CA after top dead center. When the injection start timing is 10 ° CA before top dead center,
The fuel injection time is added to this to make the injection end timing.

Before the fuel injection, since the back pressure control valve 35 is closed by the fuel injection valve drive control unit 9, the control chamber 32
Is filled with high-pressure fuel introduced from the pressure accumulating chamber 3 through the second fuel supply passage 33, and the pressure and the spring 2
The needle valve 23 is lowered by the biasing force of
Is closed.

When the fuel injection timing comes, the back pressure control valve 35 opens according to a command from the fuel injection valve drive control section 9, and the high pressure fuel in the control chamber 32 is discharged from the fuel discharge passage 34. As a result, the fuel pressure in the control chamber 32 decreases, and the fuel pressure in the fuel reservoir 31a received by the sub-piston 23c lifts the needle valve 23 and opens the fuel injection hole 21.

Initially, until the fuel injection hole 21 is completely opened, the fuel injection rate is determined by the cross-sectional area Sp of the passage around the fuel injection hole 21.
Is determined by Passage cross section Sp around fuel injection hole 21
Is larger than the cross-sectional area of the fuel injection hole 21,
The fuel injection holes 21 are fully opened.

Thereafter, when a predetermined fuel injection time has elapsed, the back pressure control valve 35 is closed by the fuel injection valve drive control unit 9. Then, since the high-pressure fuel flows into the control chamber 32 and is sealed therein, the pressure in the control chamber 32 increases, and the needle valve 23 descends by receiving this pressure, and the fuel injection hole 21 closes.

The relationship among the control chamber pressure, the amount of fuel supplied to the control chamber 32, the amount of fuel discharged from the control chamber 32, the lift amount of the needle valve, and the fuel injection rate during this time will be described with reference to the timing chart of FIG.

In this timing chart, the solid line shows the characteristics of the conventional device without the variable valve 43, and the dashed line shows the characteristics of the present device with the variable valve 43.

First, since the fuel pressure in the control chamber is high at the beginning of fuel injection, the pressure of the fuel flowing out of the control chamber is also high.
This pressure is directly applied to the valve chamber 51, and once pushes the piston 52 upward in the figure. At this time, the piston 52 and the fuel pressure are balanced by the spring constant and the like, and the cross-sectional area of the passage of the outlet orifice 34a is reduced.

In this case, the outlet orifice 34a
Since the cross-sectional area of the passage becomes smaller, the flow passage resistance increases, the outflow decreases, and the pressure in the control chamber does not readily decrease. In other words, since the pressure in the control chamber 32 gradually decreases, the lift speed of the needle valve 23 becomes slow. Therefore, at the beginning of the fuel injection, as shown by the broken line in FIG. 4, the fuel injection rate is suppressed to be low.

As a result, the combustion noise and NOx can be reduced, and the injection timing can be advanced, so that the fuel efficiency can be improved. Thereafter, since the fuel pressure in the control chamber gradually decreases, the piston 52 of the variable valve 43 moves downward in FIG. 2 by the urging force of the spring 53, and the passage cross-sectional area of the outlet orifice 43a increases. Then, the amount of fuel flowing out from the control chamber via the fuel discharge path increases, so that the lift speed of the needle valve 23 increases, and the lift amount increases. Therefore, in the latter period of the fuel injection, the fuel injection rate increases. Therefore, the output can be improved by shortening the fuel injection period, and the smoke can be reduced by reducing the afterburning.

[0048]

According to the present invention, the fuel injection rate can be changed as the pressure of the fuel flowing out of the control chamber changes from a high pressure to a low pressure, and an appropriate fuel injection rate can be obtained.

Further, since the fuel outflow variable control means is driven by the pressure of the fuel flowing out of the control chamber, it can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an apparatus according to the present invention.

FIG. 2 is a view showing a fuel injection valve according to the embodiment;

FIG. 3 is a detailed view showing the vicinity of a fuel injection hole.

FIG. 4 is a timing chart showing fuel injection characteristics of the embodiment.

[Explanation of symbols]

 1. Fuel tank as fuel supply source 2. Fuel pump 3. Fuel accumulator chamber 4. Fuel supply path 5. Fuel injection valve 6. Fuel pressure sensor 7. Control device 8. Fuel pump drive Control unit 9 fuel injection valve drive control unit 11 relief valve 12 fuel release passage 21 fuel injection hole 22 cylindrical body 23 needle valve 24 coil spring 31 first Fuel supply path 32 Control room 33 Second fuel supply path 33a Inlet orifice 34 Fuel discharge path 34a Outlet orifice 34b Return path 35 Back pressure control valve 43 Fuel outflow Variable valve 51 as variable amount control means Valve chamber 52 Piston 52a Communication passage 53 Spring S1 Accelerator sensor S2 Intake pressure sensor S3 Water temperature sensor S4: Engine speed sensor S5: Aero flow meter S6: G sensor

Claims (2)

[Claims] 1. A fuel accumulation chamber for accumulating fuel, and a high-pressure fuel accumulated in the fuel accumulation chamber is introduced into a control chamber.
The fuel injection hole is closed by pressing the valve body with the pressure of the high-pressure fuel introduced into the control chamber, and the high-pressure fuel in the control chamber is discharged from the fuel discharge path to open the fuel injection hole by reducing the pressing force of the valve body. A fuel injection device comprising: an injection valve, wherein the fuel injection device is provided in the fuel discharge passage, is driven by pressure of fuel discharged from the control chamber, and varies a passage cross-sectional area of the fuel discharge passage according to the drive. A fuel injection device comprising a fuel outflow variable control means. 2. The fuel outflow variable control means reduces the cross-sectional area of the passage when the pressure of the fuel discharged from the control chamber is high, and increases the cross-sectional area of the passage when the pressure of the fuel is low. The fuel injection device according to claim 1, wherein: