JP3099546B2 - Fuel injection valve - Google Patents

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.

[0002]

2. Description of the Related Art A back pressure chamber is formed on the top surface of a needle, the back pressure chamber is connected to the pressure control chamber, and the volume of the pressure control chamber filled with fuel is controlled by an actuator to make up the volume of the pressure control chamber. When the pressure is increased, the needle rises to open the nozzle port, and at this time, the needle comes into contact with the needle lift regulating surface to regulate the maximum lift amount of the needle, and when the volume of the pressure control chamber is decreased, the needle There is known a fuel injection valve which is urged in a valve closing direction to close a nozzle port (see Japanese Patent Application Laid-Open No. Sho 60-1369).

[0003] In this fuel injection valve, when the volume of the pressure control chamber is increased and the fuel pressure acting on the top surface of the needle is reduced, the needle rises. As a result, the needle opens the nozzle port, and fuel injection is performed. Be started. Next, when the volume of the pressure control chamber is reduced, the fuel pressure acting on the top surface of the needle, that is, the fuel pressure in the back pressure chamber is increased. As a result, the needle is biased in the valve closing direction to close the nozzle port, and thus the fuel injection is stopped.

[0004]

However, in this fuel injection valve, even if the volume of the pressure control chamber is increased to start fuel injection, the needle does not immediately rise, so that the fuel pressure in the back pressure chamber drops sharply. I do. As a result, the needle is urged at a high speed in the valve opening direction. However, when the needle is urged in the valve opening direction at a high speed in this way, the needle collides with the needle lift control surface at a high speed, so that the needle rebounds on the needle lift control surface due to the reaction force of the collision action. Become. However, when the needle rebounds, the needle closing operation is started while the needle rebounds, particularly when the injection period is short. In this case, if the valve closing operation of the needle is started while the needle is descending due to the rebound, the valve closing time of the needle is earlier than expected, whereas the needle rebounds and then rises again. If the valve closing operation of the needle is started during the start, the valve closing time of the needle is later than the scheduled time. That is, if the needle rebounds, the valve closing timing of the needle is shifted from the expected timing, and therefore, there is a problem that the injection amount is shifted from the normal injection amount.

Further, in this fuel injection valve, even if the volume of the pressure control chamber is reduced to stop the fuel injection, the needle does not immediately descend, and therefore the fuel pressure in the back pressure chamber rapidly increases. As a result, the fuel pressure in the back pressure chamber becomes high, so that the needle is urged at a high speed in the valve closing direction. However, when the needle is urged in the valve closing direction at a high speed in this way, the needle collides with the valve seat at a high speed, so that the needle is closed and then reopened due to the reaction force of the collision action. No, so-called secondary injection phenomenon occurs.

[0006]

According to a first aspect of the present invention, there is provided an upwardly-facing annular surface formed on an outer peripheral surface of a needle and a downwardly-facing annular surface formed on an inner peripheral surface of a needle insertion hole. A pressure chamber is formed between the surfaces to allow the pressure chamber and the back pressure chamber to communicate with each other through a variable throttle passage. When the volume of the pressure chamber decreases with the rise of the needle, the fluid resistance of the variable throttle passage increases, The pressure in the pressure chamber is increased to apply a downward force to the needle.

[0007]

According to a second aspect of the present invention, in order to solve the above problem, a first annular surface formed on an outer peripheral surface of a needle and a downward annular surface formed on an inner peripheral surface of a needle insertion hole are provided. And the first pressure chamber and the back pressure chamber are communicated with each other through a first variable throttle passage. When the volume of the first pressure chamber decreases with the rise of the needle, the first pressure chamber is connected to the first pressure chamber. The fluid resistance of the variable throttle passage increases to increase the pressure in the first pressure chamber to exert a downward force on the needle, and a downward annular surface formed on the outer peripheral surface of the needle and an inner peripheral surface of the needle insertion hole. A second pressure chamber is formed between the upwardly-facing annular surfaces formed in the above, and the second pressure chamber and the fuel reservoir are communicated with each other through a second variable throttle passage. As the needle descends, the second pressure chamber is formed. Flow through the second variable throttle passage when the volume of Resistance is raised the pressure in the pressure chamber of the second increase is adapted to exert a upward force on the needle.

[0009]

According to the first aspect, when the volume of the pressure control chamber is increased and the fuel pressure in the back pressure chamber is reduced, the needle is raised. When the needle rises, the volume of the pressure chamber decreases, and the fluid resistance of the variable throttle passage increases. Therefore, a large positive pressure is temporarily generated in the pressure chamber. Due to this positive pressure, a downward force acts on the upward annular surface of the needle,
As a result, the rising speed of the needle is reduced.

[0010]

In the second invention, a downward force acts on the needle due to the positive pressure temporarily generated in the first pressure chamber when the needle rises, so that the rising speed of the needle is reduced. As a result, an upward force acts on the needle due to the positive pressure temporarily generated in the second pressure chamber when the needle descends, and as a result, the descending speed of the needle is reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes a fuel injection valve housing, 2 denotes a nozzle holder having a nozzle orifice 3 at its tip, 4 denotes a needle arranged in the nozzle holder 2, and 5 denotes a housing. A fitted piston holder, 6 is a piston slidably inserted into a piston insertion hole 7 of the piston holder 5, 8 is a piezoelectric element formed of a laminate of disk-shaped piezoelectric element plates, and 9 is a guide for the piezoelectric element 8. And 10 indicate a piezoelectric element holder.

[0013] Piston holder 5 and piezoelectric element holder 1
Reference numeral 0 is fixed to a proper position in the housing 1 by a retainer 11 screwed to the housing 1. The intermediate member 5a and the nozzle holder 2 arranged between the piston holder 5 and the nozzle holder 2 are fixed at regular positions in the housing 1 by a retainer 12 screwed to the housing 1. Piston insertion hole 7 formed in piston holder 5
A pressure control chamber 13 defined by a lower end surface of the piston 6 is formed therein. The conical pressure receiving surface 1 of the needle 4
A fuel pool 16 is formed around 5. The fuel reservoir 16 is connected on one hand to the nozzle port 3 and on the other hand to a fuel supply port 18.

Referring to FIG. 2, the top surface 19 of the needle 4
A back pressure chamber 20 is formed above. A fuel hole 22 extending upward is formed at the center of the top surface of the back pressure chamber 20.
0 is connected to the pressure control chamber 13 through the fuel hole 22.
A cylindrical enlarged head 23 is integrally formed at the top of the needle 4, and the enlarged head 23 is inserted into the needle insertion hole 2 a defined by the nozzle holder 2, the intermediate member 5 a, and the inner peripheral surface of the piston holder 5. It is slidably inserted. A needle lift regulating surface 21 is provided on the inner peripheral surface of the needle insertion hole 2a.
As shown in FIG. 2B, the needle 4 comes into contact with the needle lift regulating surface 21 to regulate the maximum lift amount of the needle 4. In this embodiment, the needle lift regulating surface 21 is formed by the bottom surface of the intermediate member 5a.

An upwardly facing annular surface 26 is formed on the outer peripheral surface of the enlarged head 23 of the needle 4, and the needle insertion hole 2a
On the inner peripheral surface, a downward annular surface 27 facing the upward annular surface 26 of the needle 4 and forming the needle lift regulating surface 21 is formed. Therefore, a pressure chamber 24 whose volume decreases when the needle 4 is raised is formed between the upward annular surface 26 of the needle 4 and the downward annular surface 27 of the needle insertion hole 2a.

On the other hand, an annular gap 2 is provided between the needle 4 and the needle insertion hole 2a located between the back pressure chamber 20 and the pressure chamber 24.
5, the gap 25 is formed between the back pressure chamber 20 and the pressure chamber 24.
Are formed to communicate with the throttle passage. Therefore, part of the high-pressure fuel supplied from the fuel reservoir 16 into the pressure chamber 24 through the gap between the outer peripheral surface of the enlarged head 23 and the inner peripheral surface of the needle insertion hole 2 a is supplied to the back pressure chamber through the throttle passage 25. 20.

In this embodiment, a variable throttle 30 is formed in the throttle passage 25 on the side of the back pressure chamber 20. The variable diaphragm 30 is formed by an upward diaphragm surface 28 formed by the top surface 19 of the needle 4 and a downward diaphragm surface 29 formed in the needle insertion hole 2a. When the needle 4 rises, the throttle surface 28 of the needle and the throttle surface 2 of the needle insertion hole 2a
The distance between the variable throttles 9 is reduced, and the degree of restriction of the variable restrictor 30 is increased. As a result, the fluid resistance of the variable restrictor 30 is increased.

FIG. 3 shows a change in the fluid resistance C of the throttle passage 25 with respect to the lift amount X of the needle 4. The fluid resistance characteristic curve of the throttle passage 25 in this embodiment is represented by C1.
That is, the fluid resistance C of the throttle passage 25 increases as the needle 4 moves up. In this figure, the fluid resistance characteristic curve C
Although 1 is represented linearly, it is represented by various curves by changing the shape of the variable aperture 30 in the aperture passage 25.

Further, a compression spring 31 is disposed between the top surface of the back pressure chamber in the back pressure chamber 20 and the top surface 19 of the needle 4. The compression spring 31 urges the needle 4 in the valve closing direction by its spring force, and particularly prevents the nozzle port 3 from being accidentally opened when the valve is closed.

When the electric charge charged in the piezoelectric element 8 is discharged and the piezoelectric element 8 contracts in the axial direction, the piston 6 is raised. Even if the piston 6 is raised, the needle 4 does not immediately rise, and at this time, the fuel pressure in the pressure control chamber 13 and the fuel hole 22 rapidly decreases.
Further, at this time, the fuel pressure applied to the top surface 19 of the needle 4 decreases, and the needle 4 is raised by the fuel pressure applied to the pressure receiving surface 15. As a result, the needle 4 becomes the nozzle port 3
Is opened to start fuel injection.

When the needle 4 starts to rise, the pressure chamber 2
4 and the fuel in the pressure chamber 24 flows out into the back pressure chamber 20 via the throttle passage 25. As the needle 4 rises, the distance between the throttle surface 28 of the needle 4 and the throttle surface 29 of the needle insertion hole 2a decreases, and the throttle passage 25
, The fluid resistance of the variable throttle 30 increases. This makes it difficult for the fuel in the pressure chamber 24 to flow out to the back pressure chamber 20, and the pressure chamber 2
A positive pressure is generated in 4. As a result, a downward force acts on the upwardly-facing annular surface 26 of the needle 4, so that the rising speed of the needle 4 is reduced. Next, as shown in FIG. 2B, the needle 4 comes into contact with the needle lift regulating surface 21 to regulate the maximum lift amount. However, the fluid resistance of the variable throttle 30 causes the end of the rising operation of the needle 4. At this time, the pressure becomes largest, so that the largest positive pressure is generated in the pressure chamber 24, so that the largest downward force acts on the needle 4. For this reason, the speed of the needle 4 when the needle 4 collides with the needle lift regulating surface 21 is reduced, so that the needle 4 can be prevented from rebounding on the needle lift regulating surface. In this way, a small collision speed can be achieved when the needle 4 collides with the needle lift regulating surface 21 while securing a large rising speed when the needle 4 starts to ascend. As a result, deterioration of the accuracy of the injection amount can be prevented.

On the other hand, referring to FIG.
When the electric charge is charged and the piezoelectric element 8 extends in the axial direction, the piston 6 is lowered, and as a result, the pressure control chamber 13
Is reduced. Even if the volume of the pressure control chamber 13 is reduced, the needle 4 does not immediately descend, so that the fuel pressure in the pressure control chamber 13 and the fuel in the fuel hole 22 increases. As a result, the needle 4 is urged in the valve closing direction, so that the needle 4 starts descending.

When the needle 4 starts descending, the pressure chamber 2
Since the volume of 4 increases and the fluid resistance of the throttle passage 25 is relatively large at this time, a negative pressure is temporarily generated in the pressure chamber 24. For this reason, an upward force acts on the upward annular surface 26 of the needle 4, so that the descending speed of the needle 4 is reduced. Next, the back pressure chamber 20 is provided in the pressure chamber 24.
The fuel inside flows through the throttle passage 25, and accordingly, the needle 4 descends. As a result, the speed at which the needle 4 comes into contact with the valve seat is reduced, so that the needle 4 does not rebound at the valve seat, and therefore, it is possible to prevent an undesirable, so-called secondary injection phenomenon from occurring.

Even if the needle 4 comes into contact with the valve seat and the fuel injection is stopped, the fuel in the back pressure chamber 20 flows out through the throttle passage 25 into the pressure chamber 24, and as a result, the fuel in the back pressure chamber 20. The fuel pressure and the fuel pressure in the pressure chamber 24 become substantially equal.

FIG. 4 shows another embodiment. FIG.
4A shows a state when the valve is closed, and FIG. 4B shows a state when the valve is opened.

In this embodiment, the enlarged head 2 of the needle 4
A downward annular surface 26 is formed on the outer peripheral surface of the needle 3 and the downward annular surface 26 of the needle 4 is formed on the inner peripheral surface of the needle insertion hole 2a.
An upwardly-facing annular surface 27 is formed opposite to. Accordingly, the downward annular surface 26 of the needle 4 and the needle insertion hole 2
A pressure chamber 24 whose volume decreases when the needle 4 descends is formed between the upwardly-facing annular surface 27 a.

On the other hand, an annular gap 25 is formed between the needle 4 and the needle insertion hole 2a located between the fuel reservoir 16 and the pressure chamber 24, and this gap 25 is a restrictor communicating the fuel reservoir 16 and the pressure chamber 24. A passage is formed. Therefore, the fuel is supplied from the fuel reservoir 16 into the pressure chamber 24 through the throttle passage 25, and is supplied into the back pressure chamber 20 through the gap between the outer peripheral surface of the enlarged head 23 and the inner peripheral surface of the needle insertion hole 2a. You.

In this embodiment, the fuel pool 1 in the throttle passage 25
A variable stop 30 is formed on the sixth side. This variable aperture 30
Is formed by a downward diaphragm surface 28 formed in the enlarged head 23 and an upward diaphragm surface 29 formed in the needle insertion hole 2a. When the needle 4 descends, the distance between the throttle surface 28 of the needle and the throttle surface 29 of the needle insertion hole 2a decreases, and the degree of throttling of the variable throttle 30 increases, with the result that the fluid resistance of the variable throttle 30 increases.

The fluid resistance characteristic curve of the throttle passage 25 in this embodiment is represented by C2 in FIG. 3, that is, the fluid resistance C of the throttle passage 25 increases as the needle 4 descends. In addition, although the fluid resistance characteristic curve C2 is also represented in a straight line in this figure, it can be represented by various curves by changing the shape of the variable throttle 30 in the throttle passage 25.

When the piston 6 is lowered to stop the fuel injection and the needle 4 starts to lower, the volume of the pressure chamber 24 is reduced, and the fuel in the pressure chamber 24 is discharged through the throttle passage 25 into the fuel reservoir 16. Leaked to As the needle 4 descends, the distance between the throttle surface 28 of the needle 4 and the throttle surface 29 of the needle insertion hole 2a decreases, and the fluid resistance of the variable throttle 30 in the throttle passage 25 increases. For this reason, the fuel in the pressure chamber 24 is less likely to flow out into the fuel reservoir 16, and a positive pressure is generated in the pressure chamber 24. As a result, an upward force acts on the downward annular surface 26 of the needle 4, so that the descending speed of the needle 4 is reduced. Next, the needle 4 comes into contact with the valve seat and the fuel injection is stopped.
At the end of the lowering operation, the largest positive pressure is generated in the pressure chamber 24 at this time, so that the largest upward force acts on the needle 4. As a result, the speed of the needle 4 when the needle 4 comes into contact with the valve seat is reduced, so that the needle 4 does not rebound at the valve seat, so that it is possible to prevent a secondary injection phenomenon from occurring.

On the other hand, when the piston 6 is raised to start the fuel injection and thus the needle 4 starts to rise, the volume of the pressure chamber 24 increases, and at this time, the throttle passage 2
Since the fluid resistance of No. 5 is relatively large, a negative pressure is temporarily generated in the pressure chamber 24. For this reason, a downward force acts on the downward annular surface 26 of the needle 4, so that the rising speed of the needle 4 is reduced. Next, the fuel in the fuel reservoir 16 flows into the pressure chamber 24 through the throttle passage 25, and the needle 4 rises accordingly. As a result, the speed at which the needle 4 collides with the needle lift restricting surface 21 is reduced, so that the needle 4 does not rebound on the needle lift restricting surface 21, so that it is possible to prevent the accuracy of the injection amount from deteriorating.

Even if the needle 4 comes into contact with the needle lift regulating surface 21 and the valve opening operation of the needle 4 is completed, the fuel in the fuel reservoir 16 flows out into the pressure chamber 24 through the throttle passage 25, and as a result, Fuel pressure in reservoir 16 and pressure chamber 24
Becomes substantially equal to the fuel pressure in the inside.

FIG. 5 shows still another embodiment. FIG. 5 (A) shows the state when the valve is closed, and FIG. 5 (B) shows the state when the valve is open.

In this embodiment, the enlarged head 2 of the needle 4
3 has an upwardly directed annular surface 26a and a downwardly directed annular surface 26b. In addition, an upward annular surface 26a of the needle 4 is provided on the inner peripheral surface of the needle insertion hole 2a.
Is formed, and an upwardly directed annular surface 27b opposed to the downwardly directed annular surface 26b of the needle 4 is formed. Therefore, a first pressure chamber 24a whose volume decreases when the needle 4 rises is formed between the upward annular surface 26a of the needle 4 and the downward annular surface 27a of the needle insertion hole 2a. A second pressure chamber 24b is formed between the annular surface 26b and the upward annular surface 27b of the needle insertion hole 2a, the volume of which decreases when the needle 4 descends.

On the other hand, an annular first gap 25a is formed between the needle 4 and the needle insertion hole 2a located between the back pressure chamber 20 and the first pressure chamber 24a.
Defines a first throttle passage that connects the back pressure chamber 20 and the first pressure chamber 24a. An annular second gap 25b is formed between the needle 4 and the needle insertion hole 2a located between the fuel pool 16 and the second pressure chamber 24b. The second gap 25b is formed between the fuel pool 16 and the second pressure chamber 24b. Pressure chamber 2
4b is formed. Therefore, the fuel flows from the fuel reservoir 16 to the second throttle passage 25b.
Is supplied to the inside of the second pressure chamber 24b through the second pressure chamber 24b.
The first pressure chamber 24a is supplied to the first pressure chamber 24a through a gap between the inner peripheral surfaces, and further, the first throttle chamber 25
The pressure is supplied into the back pressure chamber 20 via a.

In this embodiment, a first variable throttle 30a is formed on the back pressure chamber 20 side of the first throttle passage 25a, and a second variable throttle 30b is formed on the fuel pool 16 side of the second throttle passage 25b. It is formed. The first variable throttle 30a has an upwardly directed throttle surface 28 formed by the top surface 19 of the needle 4.
a, and a downward throttle surface 29a formed in the needle insertion hole 2a. When the needle 4 rises, an upward throttle surface 28a of the needle 4 and the needle insertion hole 2a are formed.
The distance between the downwardly directed throttle surfaces 29a decreases, and the fluid resistance of the first variable throttle 30a increases. On the other hand, the second
The variable throttle 30b is formed by a downward throttle surface 28b formed in the needle 4 and an upward throttle surface 29b formed in the needle insertion hole 2a. The distance between the upward restricting surfaces 29b of the holes 2a decreases, and the fluid resistance of the second variable restrictor 30b increases.

The fluid resistance characteristic curves of the first throttle passage 25a and the second throttle passage 25b in this embodiment are represented by C1 and C2 in FIG.
As the needle 4 descends, the fluid resistance C of the first throttle passage 25a increases.
The fluid resistance C of 5b increases.

When the piston 6 is raised to start fuel injection and thus the needle 4 starts to rise, the volume of the first pressure chamber 24a decreases and the fuel in the first pressure chamber 24a is reduced by the first throttle. It flows out into the back pressure chamber 20 through the passage 25a. As the needle 4 rises, the distance between the upward throttle surface 28a of the needle 4 and the downward throttle surface 29a of the needle insertion hole 2a decreases, and the fluid resistance of the first variable throttle 30a increases. For this reason, the fuel in the first pressure chamber 24a does not easily flow out to the back pressure chamber 20, and a positive pressure is generated in the first pressure chamber 24a. As a result, a downward force acts on the upward annular surface 26a of the needle 4, and the rising speed of the needle 4 is reduced. Next, as shown in FIG. 5B, the needle 4 comes into contact with the needle lift regulating surface 21 to regulate the maximum lift amount. However, the fluid resistance of the first variable throttle 30a increases the needle resistance. Since it becomes the largest just before the end of the operation, the largest positive pressure is generated in the first pressure chamber 24a at this time, so that the largest downward force acts on the needle 4. For this reason, the speed of the needle 4 when the needle 4 collides with the needle lift regulating surface 21 is reduced, so that the needle 4 can be prevented from rebounding on the needle lift regulating surface 21. As a result, deterioration of the accuracy of the injection amount can be prevented.

On the other hand, when the piston 6 is lowered to stop the fuel injection and the needle 4 starts to lower, the volume of the second pressure chamber 24b decreases, and the fuel in the second pressure chamber 24b is released from the second pressure chamber 24b. Through the throttle passage 25b. As the needle 4 descends, the distance between the downward throttle surface 28b of the needle 4 and the upward throttle surface 29b of the needle insertion hole 2a decreases, and the fluid resistance of the second variable throttle 30b increases. For this reason, it is difficult for the fuel in the second pressure chamber 24b to flow out to the fuel pool 16, and a positive pressure is generated in the second pressure chamber 24b. As a result, an upward force acts on the downward annular surface 26b of the needle 4, and the lowering speed of the needle 4 is reduced. Next, the needle 4 comes into contact with the valve seat to stop the fuel injection. However, since the fluid resistance of the second variable throttle 30b becomes the largest just before the end of the descending operation of the needle 4, the second pressure chamber 24b The largest positive pressure is generated therein, so that the largest upward force acts on the needle 4. As a result, the speed of the needle 4 when the needle 4 comes into contact with the valve seat is reduced, so that the needle 4 does not rebound at the valve seat, and therefore the occurrence of the secondary injection phenomenon can be prevented.

[0040]

According to the present invention, it is possible to prevent the accuracy of the injection quantity from deteriorating by decreasing the valve opening speed of the needle during fuel injection, and to prevent the secondary injection phenomenon from occurring by decreasing the valve closing speed of the needle during fuel stop. .

[Brief description of the drawings]

FIG. 1 is a side sectional view of a fuel injection valve.

FIG. 2 is an enlarged side sectional view of a portion A of the fuel injection valve shown in FIG.

FIG. 3 is a diagram showing a change in fluid resistance of a throttle passage with respect to a lift amount of a needle in the fuel injection valve shown in FIG. 1;

FIG. 4 is an enlarged side sectional view of a part of a fuel injection valve showing another embodiment.

FIG. 5 is an enlarged side sectional view of a part of a fuel injection valve showing still another embodiment.

[Explanation of symbols]

 2a Needle insertion hole 4 Needle 6 Piston 8 Piezoelectric element 13 Pressure control chamber 20 Back pressure chamber 24 Pressure chamber 25 Throttle passage 30 Variable throttle

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-1369 (JP, A) JP-A-59-190472 (JP, A) JP-A-63-104679 (JP, U) JP-A-1 160168 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 39/00-71/04

Claims (2)

(57) [Claims] 1. A back pressure chamber is formed on a top surface of a needle, the back pressure chamber is connected to the pressure control chamber, and a volume of the pressure control chamber filled with fuel is controlled by an actuator to form a volume of the pressure control chamber. When the pressure is increased, the needle rises to open the nozzle port, and at this time, the needle comes into contact with the needle lift regulating surface to regulate the maximum lift amount of the needle, and when the volume of the pressure control chamber is decreased, the needle The pressure chamber is urged between the upward annular surface formed on the outer peripheral surface of the needle and the downward annular surface formed on the inner peripheral surface of the needle insertion hole in the fuel injection valve which is urged in the valve closing direction to close the nozzle port. The pressure chamber and the back pressure chamber are communicated with each other by a variable throttle passage. When the volume of the pressure chamber decreases with the rise of the needle, the fluid resistance of the variable throttle passage increases, and the pressure chamber increases. The fuel injection valve is designed to increase the pressure of the fuel and apply a downward force to the needle. 2. A back pressure chamber is formed on the top surface of the needle, and the back pressure chamber is connected to the pressure control chamber, and the volume of the pressure control chamber filled with fuel is controlled by an actuator to thereby increase the volume of the pressure control chamber. When the pressure is increased, the needle rises to open the nozzle port, and at this time, the needle comes into contact with the needle lift regulating surface to regulate the maximum lift amount of the needle, and when the volume of the pressure control chamber is decreased, the needle Is urged in the valve closing direction to close the nozzle port. In the fuel injection valve, the first annular surface is formed between the upward annular surface formed on the outer peripheral surface of the needle and the downward annular surface formed on the inner peripheral surface of the needle insertion hole. A pressure chamber is formed and the first pressure chamber and the back pressure chamber are communicated with each other by a first variable throttle passage. When the volume of the first pressure chamber decreases with the rise of the needle, the first variable chamber is closed. Throttling The fluid resistance of the needle is increased to increase the pressure in the first pressure chamber to apply a downward force to the needle, and to form a downward annular surface formed on the outer peripheral surface of the needle and an inner peripheral surface of the needle insertion hole. A second pressure chamber is formed between the upwardly directed annular surfaces, and the second pressure chamber and the fuel reservoir are communicated with each other through a second variable throttle passage. As the needle descends, the volume of the second pressure chamber decreases. A fuel injection valve in which when the pressure decreases, the fluid resistance of the second variable throttle passage increases, thereby increasing the pressure in the second pressure chamber to exert an upward force on the needle.