JP2959224B2 - Fuel injection device - 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 device for accumulating high-pressure fuel in a common rail and supplying the accumulated fuel to an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, a common rail type fuel injection device has been known in which high-pressure fuel is accumulated in a kind of surge tank called a common rail, and the accumulated high-pressure fuel is injected into an internal combustion engine by opening and closing an injector. -165858
And the like) have been proposed. As shown in FIG. 8, for example, this common rail type fuel injection device includes a nozzle 101 for injecting high-pressure fuel, and a three-way solenoid valve 102 for controlling the injection timing and injection amount of the nozzle 101.

The nozzle 101 includes a needle 103 for opening and closing the injection hole, a hydraulic piston 104 for driving the needle 103, a back pressure chamber 105 for applying a back pressure to the hydraulic piston 104, and a nozzle 101 disposed in the back pressure chamber 105. Valve 107, a spring 108 for pressing the valve 107,
And a seat 106 for holding the spring 108 (see FIGS. 9 and 10).

[0004] This common rail type fuel injection device 100
The operation of will be briefly described with reference to FIGS. 9 and 10. At the start of fuel injection, as shown in FIG.
The discharge of the high-pressure fuel in the back pressure chamber 105 through the communication passage 109 is started by the operation of 02, so that the valve 107 is seated on the valve seat 111 of the valve body 110 of the three-way solenoid valve 102, and the fuel is discharged through the orifice. Because of the outflow, the hydraulic piston 104 slowly rises, the needle 103 moves by the full lift amount, and fuel injection is started. Further, at the end of fuel injection, when the introduction of high-pressure fuel from inside the back pressure chamber 105 via the communication passage 109 by the operation of the three-way solenoid valve 102 is started, the valve 107 is lowered. At this time, as shown in FIG. 10, high-pressure fuel is instantaneously introduced into the back pressure chamber 105 through the outer periphery of the valve 107. For this reason,
When the hydraulic piston 104 descends at a stretch until the needle 103 is seated on the seat portion, good injection cut (sharp cut) is obtained.

[0005]

However, in the conventional common rail type fuel injection device 100, when the fuel injection is completed, the instantaneous introduction of high-pressure fuel into the back pressure chamber 105,
In addition, the seating speed of the needle 103 is high due to pressure pulsation caused by the instantaneous introduction of high-pressure fuel, and the nozzle body 11
There was a problem that a very large impact load was applied to the seat portion of No. 2. In order to obtain sufficient strength against such an impact load of the seat, it is necessary to increase the thickness of the nozzle body 112 around the seat. However, if the plate thickness around the sheet portion of the nozzle body 112 is simply increased, the passage length of the injection hole also increases, and the passage resistance of the injection hole increases. For this reason, in order to obtain the same passage resistance of the injection hole as before the plate thickness is increased, it is necessary to increase the volume of the suck chamber 113.

However, since the suck chamber 113 is located downstream of the seat portion of the nozzle body 112 and has an injection hole formed in the wall thereof, the fuel in the suck chamber 113 is maintained even after the fuel injection is completed. May flow out into the combustion chamber. For this reason, if the volume of the sack chamber 113 is large, adverse effects such as deterioration of the fuel consumption rate and increase of HC are caused, so that the sac volume of the nozzle body 112 cannot be easily increased. An object of the present invention is to provide a fuel injection device that reduces an impact load on a seat portion of a tubular member on which a needle is seated while maintaining good injection cutoff at the end of injection.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided an injection hole for injecting fuel, a seat portion connected to the injection hole, a first shoulder formed on the seat portion side, and a first shoulder facing the first shoulder. 2
A main back pressure chamber surrounded by a shoulder, a sub back pressure chamber opened at the first shoulder, and having an inner diameter smaller than the main back pressure chamber;
A tubular member having an opening at a shoulder portion and having a communication passage having an inner diameter smaller than the main back pressure chamber, and a needle disposed slidably in the tubular member and closing the injection hole by sitting on the seat portion; Slidably disposed in the sub-back pressure chamber,
The seating the needle in the seat, and a drive member for separating said main first that Ru is movably disposed back pressure chamber
A valve, a second valve Ru disposed movably from the first valve to the second shoulder portion of the main back pressure chamber, and the introduction of fuel into the via communication path the main back pressure in the Switching means for switching between discharge of fuel from the main back pressure chamber and
The first valve is configured to introduce fuel into the main back pressure chamber.
And sitting on the first shoulder while pressing the drive member
Shut off the main back pressure chamber and the sub back pressure chamber, and
When fuel is discharged from the pressure chamber,
A first valve body that moves toward the second shoulder, and the first valve body
The main back pressure chamber and the sub back pressure chamber are provided so as to be able to communicate with each other,
Fuel is introduced into the main back pressure chamber and the first valve body is
1 When sitting on the shoulder, the back pressure from the main back pressure chamber
Having a first orifice for introducing the fuel into the chamber, the second
When fuel is introduced into the main back pressure chamber, the valve
Move to one valve side and discharge fuel from the main back pressure chamber
Then, the main back pressure chamber is seated on the second shoulder and communicates with the main back pressure chamber.
A second valve body that shuts off the passage, and the second valve body
The main back pressure chamber and the communication passage are provided so as to be able to communicate with each other,
The fuel is discharged from the back pressure chamber, and the communication passage extends from the main back pressure chamber.
Characterized by having a second orifice for discharging fuel to the
It adopted the technical means to be.

[0008]

[Action]

(At the time of starting fuel injection) According to the present invention, when the switching means starts discharging fuel from the main back pressure chamber through the communication passage , the second valve body of the second valve is seated on the second shoulder. The main back pressure chamber and the communication passage are shut off.
However, the second orifice formed in the second valve body slows the rate of discharging fuel from the main back pressure chamber to the communication passage, so that the first valve body of the first valve is driven by the second shoulder with the driving member. Move slowly to the side. When the driving member projects from the first shoulder into the main back pressure chamber and the needle linked to the driving member moves by a full lift amount, the injection hole is opened and fuel injection is started. (When Fuel Injection Ends) According to the present invention, when the introduction of fuel into the main back pressure chamber via the communication path by the switching means is started, the second valve body is separated from the second shoulder and moved toward the first valve. To move, fuel is introduced into the main back pressure chamber at a stretch. Therefore, the first valve body is quickly seated on the first shoulder while pressing the drive member to shut off the main back pressure chamber and the sub back pressure chamber, whereby the injection is quickly stopped. Thereafter, the introduction speed of the fuel from the main back pressure chamber to the sub back pressure chamber is reduced by the first orifice formed in the first valve body . Therefore, the moving speed of the driving member is reduced by restricting the introduction speed of the fuel into the auxiliary back pressure chamber immediately before the needle is seated on the seat portion of the tubular member. That is, the seating speed of the needle is reduced immediately before the needle is seated on the seat portion of the tubular member, so that the impact load of the seat portion of the tubular member is reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel injection device according to the present invention will be described based on one embodiment shown in FIGS. FIG. 1A is a diagram showing a main part of a common rail type fuel injection device.
FIG. 2B is a view showing the tip of the nozzle body, and FIG.
FIG. 1 is a view showing the entire structure of a common rail type fuel injection device. The common rail type fuel injection device 1 is attached to each cylinder of a diesel engine (not shown) and is connected to an introduction pipe (not shown) branched from a common surge tank (not shown). In the common rail type fuel injection device 1, high-pressure fuel pumped from a surge tank by a fuel pump (not shown) rotated by a diesel engine is always supplied from an introduction pipe.

As shown in FIG. 2, such a common rail type fuel injection device 1 includes a nozzle needle 2, a nozzle body 3, a hydraulic piston 4, a nozzle holder 5, a three-way solenoid valve 6, and the like. A nozzle (injection valve) is constituted by the nozzle needle 2, the nozzle body 3, the hydraulic piston 4, and the nozzle holder 5.

As shown partially in FIG. 1B, the nozzle needle 2 has a seat portion 21 which is seated on the nozzle seat portion 33 of the nozzle body 3 at the distal end. The nozzle needle 2 has an end connected to the hydraulic piston 4, and the hydraulic piston 4 moves toward the three-way solenoid valve 6, thereby separating the seat 21 from the nozzle seat 33 and returning the hydraulic piston 4 to its original position. As a result, the seat portion 21 is seated on the nozzle seat portion 33. In addition, this nozzle needle 2
FIG. 7 shows the relationship between the start of fuel injection and the end of fuel injection.
As shown in the time chart of FIG. In FIG. 7, the upper end position is the nozzle needle 2.
Represents a full lift.

As shown partially in FIG. 1B, the nozzle body 3 slidably holds the nozzle needle 2 on its inner periphery, and high-pressure fuel is constantly supplied from a surge tank via an introduction pipe. Fuel reservoir 31, injection hole 3 for injecting high pressure fuel
2, a nozzle seat portion 33 connected to the injection hole 32 and on which the nozzle needle 2 is seated, and a suck chamber 34 formed at the tip. The injection of the high-pressure fuel from the injection holes 32 is performed when the nozzle needle 2 separates from the nozzle seat portion 33 and the fuel reservoir 31 and the suck chamber 34 communicate with each other.

The hydraulic piston 4 is a driving member of the present invention. The lower end of the hydraulic piston 4 is connected to the nozzle needle 2 via a pressure pin 41 in FIG. 2 and moves upward in FIG. 2 (toward the three-way solenoid valve 6) by overcoming the urging force of the coil spring 42. The hydraulic piston 4 is
When the back pressure becomes high, the pressure in the nozzle body 3 and the urging force of the coil spring 42 are overcome due to the difference in the pressure receiving area, and the pressure is reduced below the nozzle body 3 in FIG.
Go to

The nozzle holder 5 includes a fuel passage 51, a main back pressure chamber 52, a sub back pressure chamber 53, a first valve 7, and a second valve 8.
And a coil spring 9. The fuel passage 51 is
The fuel reservoir 31 in the nozzle body 3 communicates with the introduction pipe, and is a passage that always guides the high-pressure fuel to the fuel reservoir 31.
As shown in FIGS. 3 to 6, the main back pressure chamber 52 is opened at the end face 54 of the nozzle holder 5 on the side of the three-way solenoid valve 6, and has a first step formed on the nozzle body 3 side. It is enclosed between the shoulder 55 and a second shoulder 56 formed on the end face of the three-way solenoid valve 6. The auxiliary back pressure chamber 53 has a smaller diameter than the main back pressure chamber 52, and a first stepped shoulder 55
Is communicated through. The sub-back pressure chamber 53 slidably holds the hydraulic piston 4.

The main back pressure chamber 52 and the sub back pressure chamber 53 have a high internal pressure when high-pressure fuel is supplied from the three-way solenoid valve 6 and a low internal pressure when high-pressure fuel is discharged from the inside. Become. Further, the main back pressure chamber 52 and the sub back pressure chamber 53
When the pressure becomes high, the hydraulic piston 4 is configured to move more than the first valve 7 toward the nozzle needle 2 by a predetermined lift amount L (see FIG. 1) from the first stepped shoulder portion 55. Note that the first stepped shoulder portion 55 is a first shoulder portion of the present invention and has an annular shape, and the second stepped shoulder portion 56 is a second shoulder portion of the present invention and has an annular shape. Present.

As shown in FIGS. 3 to 6, the first valve 7 has a cylindrical shape, and is disposed so as to be able to reciprocate in the first back shoulder 55 of the main back pressure chamber 52. I have. The first valve 7 is located between the outer peripheral surface and the inner peripheral surface of the nozzle holder 5.
The outer diameter is smaller than the diameter of the main back pressure chamber 52 so that a gap is formed.
A first valve body having a diameter (hereinafter, referred to as a first valve 7), and a first surface communicating with an end surface 71 on the side of the first stepped shoulder 55 and an end surface 72 on the side of the second stepped shoulder 56 at the center. An orifice 73 is provided. The first orifice 73 communicates the main back pressure chamber 52 with the sub back pressure chamber 53, and delays the introduction speed of high-pressure fuel from the main back pressure chamber 52 to the sub back pressure chamber 53 to reduce the hydraulic piston 4.
Is to slow down the moving speed. When the hydraulic piston 4 protrudes into the main back pressure chamber 52, the end surface 71 of the first valve 7 on the side of the first stepped shoulder portion 55 is always seated. When high-pressure fuel is introduced into the main back pressure chamber 52, the first valve 7 presses the hydraulic piston 4 toward the nozzle needle 2 while the end face 71 is seated on the first shoulder 55 with the main back pressure. When the communication between the pressure chamber 52 and the sub-back pressure chamber 53 is interrupted and the high-pressure fuel is discharged from the main back pressure chamber 52, the end face 71 moves away from the first stepped shoulder 55 together with the hydraulic piston 4.

As shown in FIGS. 3 to 6, the second valve 8 has a cylindrical shape, and is disposed so as to be able to reciprocate within the second shoulder 56 of the main back pressure chamber 52. I have. The second valve 8 is provided between the outer peripheral surface and the inner peripheral surface of the nozzle holder 5.
The outer diameter is smaller than the diameter of the main back pressure chamber 52 so that a gap is formed.
A second orifice having a diameter and communicating between a second valve body (hereinafter referred to as a second valve 8) and an end face 81 on the side of the first stepped shoulder 55 and an end face 82 on the side of the second stepped shoulder 56 at the center. 83 . The second orifice 83 communicates with the main back pressure chamber 52 and a communication passage 66 described later, delays the discharge speed of the high-pressure fuel from the main back pressure chamber 52 to the communication passage 66, and reduces the moving speed of the hydraulic piston 4. Is what you do. When the high-pressure fuel is introduced into the main back pressure chamber 52, the second valve 8 moves the end face 82 away from the second stepped shoulder portion 56 and the coil spring 9
When the high-pressure fuel is discharged from the main back pressure chamber 52, the first valve 7 is moved with the first valve 7 via the coil spring 9 and the end face 82 is moved to the second stepped shoulder 56. And the communication state between the main back pressure chamber 52 and the communication passage 66 is shut off. The end faces 71, 8 of the first and second valves 7, 8
2, that is, the contact surfaces of the first and second valves 7, 8 with the first and second stepped shoulders 55, 56 are flat-finished to maintain the sealing performance.

As shown in FIGS. 3 to 6, the coil spring 9 is supported by the end face 72 of the first valve 7 and the end face 81 of the second valve 8, and connects the first valve 7 to the shoulder with the first step. The second valve 8 is urged toward the second stepped shoulder 56 side.

The three-way solenoid valve 6 is a switching means of the present invention, and as shown in FIG.
2. It has an outer valve 63 and a valve body 64. The inner valve 62 is slidably disposed in the outer valve 63. The outer valve 63 is slidably disposed in the valve body 64 and has an oil passage 65 inside. The valve body 64 slidably holds the outer valve 63 on the inner periphery, and has a communication passage 66, fuel passages 67, 6 therein.
8 and a storage chamber 69 are formed. Note that the valve body 64, together with the nozzle body 3 and the nozzle holder 5, constitutes the tubular member of the present invention. The communication passage 66 opens at the nozzle holder side end surface (second shoulder 56) and faces the main back pressure chamber 52 of the nozzle holder 5. This communication path 66
One end communicates with the main back pressure chamber 52 of the nozzle holder 5 and the other end communicates with a storage chamber 69 that stores the outer valve 63. The fuel passage 67 opens at the end face on the nozzle holder 5 side, and high-pressure fuel is always introduced into the inside thereof. One end of the fuel passage 67 communicates with the fuel passage 51 of the nozzle holder 5 and the other end communicates with the storage chamber 69. Fuel passage 68
Has an opening at the end face on the nozzle holder 5 side, one end communicating with a low-pressure line (not shown) for returning fuel into the surge tank, and the other end communicating with the storage chamber 69.

When the coil 61 is turned on, the three-way solenoid valve 6 moves the outer valve 63 upward in FIG. 2 to cut off the communication between the communication passage 66 and the fuel passage 67, and The high pressure fuel in the main back pressure chamber 52 of the nozzle holder 5 is discharged by communicating the fuel passage 68 with the storage chamber 69 via the storage chamber 69. Further, the three-way solenoid valve 6 includes a coil 6
When 1 is turned off, only the outer valve 63 is moved downward in FIG. 2 to cut off the communication state between the communication passage 66 and the fuel passage 68, and the communication passage 66 and the fuel passage 67 are connected via the oil passage 65. The high-pressure fuel is introduced into the main back pressure chamber 52 of the nozzle holder 5 through the communication.

The operation of the common rail type fuel injection device 1 will be described with reference to FIGS. When the coil 61 of the three-way solenoid valve 6 is turned off, the main back pressure chamber 52 and the sub back pressure chamber 53 are filled with high-pressure fuel, and the main back pressure chamber 52
And the internal pressure of the auxiliary back pressure chamber 53 is high. Therefore, as shown in FIGS. 1A and 2, the end face 71 of the first valve 7 is seated on the shoulder 55 with the first step, and the hydraulic piston 4 is moved from the end face 71 of the first valve 7 to a predetermined position. It is arranged at a position lowered by the lift amount L. Therefore, the nozzle needle 2 connected to the hydraulic piston 4 via the pressure pin 41 is arranged at the initial lift position a (see the time chart in FIG. 7). As a result, the seat 21 of the nozzle needle 2 is seated on the nozzle seat 33 of the nozzle body 3 as shown in FIG.
The fuel pool 31 and the suck chamber 34 are shut off. Therefore, fuel is not injected from the injection holes 32. In addition,
When the high-pressure fuel is filled in the main back pressure chamber 52 and the communication passage 66, the pressures applied to both end faces 81 and 82 of the second valve 8 are balanced as shown in FIGS. The end surface 82 of the second valve 8 is also seated on the second shoulder 56 by the urging force of the coil spring 9.

When the coil 61 of the three-way solenoid valve 6 is turned on, the high-pressure fuel in the communication passage 66 is discharged and the main back pressure chamber 52
The high-pressure fuel in the sub-back pressure chamber 53 is also discharged through the second orifice 83 formed in the second valve 8, and the internal pressure of the main back pressure chamber 52 and the sub-back pressure chamber 53 becomes low. Therefore, as shown in FIG. 3, the hydraulic piston 4 rises and comes into contact with the end face 71 of the first valve 7, and further as the high-pressure fuel in the main back pressure chamber 52 is discharged, the hydraulic piston 4 and the first The valve 7 rises more slowly than the first stepped shoulder 55. Therefore, the nozzle needle 2 is moved to the full lift position b.
(See the time chart of FIG. 7). As a result, the seat portion 21 of the nozzle needle 2 is separated from the nozzle seat portion 33 of the nozzle body 3 more slowly, so that the fuel reservoir 31 and the suck chamber 34 communicate with each other, and fuel injection from the injection holes 32 is started. You.

During the injection period, as shown in FIG. 4, the internal pressures of the main back pressure chamber 52 and the sub back pressure chamber 53 are low, and the hydraulic piston 4 contacts the end face 71 of the first valve 7. Since the nozzle needle 2 is arranged at the full lift position in the contact state, the nozzle needle 2 is also arranged at the full lift position c (see the time chart of FIG. 7).

When the fuel injection is completed, the coil 61 of the three-way solenoid valve 6 is turned off, high-pressure fuel is introduced into the communication passage 66, and the pressure in the communication passage 66 becomes high. When pushed down, the end face 82 of the second valve 8 is separated from the second shoulder 56. Therefore, high-pressure fuel is introduced into the main back pressure chamber 52 at a stretch through a gap between the outer peripheral surface of the second valve 8 and the inner peripheral surface of the nozzle holder 5,
The pressure in the main back pressure chamber 52 becomes high at a stretch, and the first valve 7 is quickly pushed down with the hydraulic piston 4 by this pressure, and as shown in FIG. The nozzle needle 2 is instantly seated on the portion 55, and is positioned at the lift position d (see the time chart of FIG. 7).
Good jet cutoff is achieved.

After the end face 71 of the first valve 7 is instantly seated on the shoulder 55 with the first step, the introduction speed of the high-pressure fuel into the sub-back pressure chamber 53 depends on the diameter of the first orifice 73. Therefore, the moving speed of the hydraulic piston 4 becomes slow. Thereafter, as shown in FIG. 6, when the hydraulic piston 4 moves away from the end face 71 of the first valve 7 and then moves down by a predetermined lift amount L, the nozzle needle 2 moves to the initial lift position e (see the time chart in FIG. 7). Return to). Therefore,
The seat portion 21 of the nozzle needle 2 is seated on the nozzle seat portion 33 of the nozzle body 3, and the fuel reservoir 31 and the suck chamber 34 are shut off.

The seating speed of the nozzle needle 2 is lower than that of the conventional one because the moving speed of the hydraulic piston 4 is slower, and the seating speed of the nozzle needle 2 when the nozzle needle 2 is seated on the nozzle seat portion 33 of the nozzle body 3 is reduced. The impact load on the part 33 is considerably reduced. As described above, in the common rail type fuel injection device 1, when the fuel injection is completed, the nozzle needle 2 is moved to the nozzle seat portion 33 of the nozzle body 3.
By suppressing the seating speed of the nozzle needle 2 immediately before seating, the impact load on the nozzle seat portion 33 of the nozzle body 3 can be significantly reduced in a state where good jetting is maintained. As a result, there is no need to increase the strength of the nozzle sheet portion 33 from the current level, and it is not necessary to increase the thickness around the nozzle sheet portion 33. Therefore, since the volume of the suck chamber 34 does not increase, it is possible to prevent adverse effects such as deterioration of the fuel consumption rate, increase of the exhaust gas temperature and increase of HC.

(Modification) In this embodiment, the switching means is constituted by one three-way solenoid valve 6, but the switching means may be constituted by a plurality of solenoid valves or the like. In this embodiment, the tubular member is composed of the three tubular members of the nozzle body 3, the nozzle holder 5 and the valve body 64. However, one or two tubular members are used.
It may be composed of two tubular members, or may be composed of four or more tubular members.

In this embodiment, the nozzle needle 2 is driven by the hydraulic piston 4 via the pressure pin 41. However, the needle may be directly driven by a driving member. In the present embodiment, the contact surfaces of the first and second shoulders 55 and 56 are flat with respect to the contact surfaces of the first and second valves 7 and 8. The contact surfaces of the first and second shoulders 55 and 56 may be inclined surfaces or curved surfaces with respect to the contact surfaces 7 and 8. Further, the contact surfaces of the first and second valves 7, 8 may be inclined surfaces or curved surfaces with respect to the contact surfaces of the first and second shoulder portions 55, 56. Further, the coil spring 9 between the first and second valves 7 and 8 may not be provided.

[0029]

As described above, according to the present invention, when the fuel injection is completed, the moving speed of the needle is decreased immediately before the needle is seated on the seat portion, so that the impact of the seat portion of the tubular member can be maintained in a state in which good injection is maintained. The load can be reduced.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing a main part of a common rail type fuel injection device of the present invention, and FIG. 1B is a cross-sectional view showing a tip portion of a nozzle body of the present invention.

FIG. 2 is a sectional view showing the overall structure of a common rail type fuel injection device of the present invention.

FIG. 3 is a sectional view showing a main part of a common rail type fuel injection device of the present invention.

FIG. 4 is a sectional view showing a main part of a common rail type fuel injection device of the present invention.

FIG. 5 is a sectional view showing a main part of a common rail type fuel injection device of the present invention.

FIG. 6 is a sectional view showing a main part of a common rail type fuel injection device of the present invention.

FIG. 7 is a time chart showing the lift amount of the nozzle needle of the present invention.

FIG. 8 is a cross-sectional view showing the entire structure of a conventional common rail type fuel injection device.

FIG. 9 is a cross-sectional view showing a main part of a conventional common rail type fuel injection device.

FIG. 10 is a cross-sectional view showing a main part of a conventional common rail type fuel injection device.

[Description of Signs] 1 Common rail type fuel injection device 2 Nozzle needle 3 Nozzle body (tubular member) 4 Hydraulic piston (drive member) 5 Nozzle holder (tubular member) 6 Three-way solenoid valve (switching means) 7 First valve (No. 1 valve body) 8 2nd valve (2nd valve body) 32 Injection hole 33 Nozzle seat part 34 Suck chamber 52 Main back pressure chamber 53 Secondary back pressure chamber 55 First shoulder (first shoulder) 56 Second Stepped shoulder (second shoulder) 64 Valve body (tubular member) 66 Communication passage 73 First orifice 83 Second orifice

Claims (1)

(57) [Claims] (A) an injection hole for injecting fuel, a seat connected to the injection hole, a first shoulder formed on the seat and a second shoulder opposed to the first shoulder. An enclosed main back pressure chamber, a sub back pressure chamber that opens at the first shoulder and has an inner diameter smaller than the main back pressure chamber, and an opening at the second shoulder that has an inner diameter smaller than the main back pressure chamber A tubular member having a communication passage; (b) a needle slidably disposed within the tubular member and closing the injection hole by sitting on the seat portion; and (c) sliding into the auxiliary back pressure chamber. capable disposed, and a drive member for seating, and separating the said needle to said seat portion, and a first valve Ru disposed movably in (d) of the main back pressure chamber, (e) the from the first valve a second valve Ru disposed movably within the main back pressure chamber of the second shoulder portion, (f) the communication And a switching means for switching the discharge of fuel from the introduction to the main back pressure chamber of the fuel to the main back pressure chamber via the first valve, the fuel is introduced into the main back pressure chamber
And sitting on the first shoulder while pressing the drive member
Shut off the main back pressure chamber and the sub back pressure chamber, and
When fuel is discharged from the pressure chamber,
A first valve body that moves toward the second shoulder, and the first valve body
The main back pressure chamber and the sub back pressure chamber are provided so as to be able to communicate with each other,
Fuel is introduced into the main back pressure chamber and the first valve body is
1 When sitting on the shoulder, the back pressure from the main back pressure chamber
A first orifice for introducing fuel into the chamber, wherein the second valve introduces fuel into the main back pressure chamber;
And the first valve side, and the fuel flows from the main back pressure chamber.
When the material is discharged, the main back pressure chamber is seated on the second shoulder portion.
Valve body for shutting off the communication path and the communication passage, and the second valve
A body is provided so that the main back pressure chamber and the communication passage can communicate with each other.
The fuel is discharged from the main back pressure chamber, and the fuel is discharged from the main back pressure chamber.
A second orifice for discharging fuel to the communication passage;
A fuel injection device characterized by the above-mentioned.