JP2002048024A - Fuel injector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a malfunction such as a fluctuation in a lift quantity, for example, by a temperature by surely fixing a regulating position of a valve member at low lift time without varying the lift quantity of the valve member by applying fuel pressure in the nozzle port blocking-up direction in a conventional fuel injector. SOLUTION: A lift regulating piston 12 slidable in the shaft direction is coaxially arranged with the valve member 6, and a slide position of this lift regulating piston 12 is mechanically switched by the fuel pressure. When lifting the valve member 6, the lift quantity of the valve member 6 is switched to a high lift and a low lift by the slide position of the lift regulating piston 12. Thus, since the lift regulating piston 12 for switching the lift quantity is mechanically switched by the fuel pressure, the high lift and the low lift can be surely switched. That is, the malfunction such as a fluctuation in the lift quantity, for example, by the temperature can be eliminated so that switching control of a fuel injection rate can be stably performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine (hereinafter referred to as "internal combustion engine").
(Referred to as an engine).

[0002]

2. Description of the Related Art Conventionally, in a diesel engine, in order to achieve both low emission (NOx, HC, black smoke), high output, and low fuel consumption, the fuel injection rate is varied according to the operating conditions of the engine. Is required. In order to fulfill this demand, a nozzle having a two-stage valve opening pressure using two springs to bias a valve member is known as a conventional technique. However, with this technique, the fuel pressure pumped from the fuel injection pump varies depending on the engine operating state, and it is difficult to achieve the injection rate required by the engine according to all operating conditions.

Therefore, there is a conventional fuel injection valve disclosed in, for example, Japanese Patent Application Laid-Open No. 8-326519, which is provided with a pressure chamber for applying fuel pressure to a valve member in a direction of closing an injection hole. This means that the lift amount of the valve member is variable by the magnitude relationship between the force that directs the injection hole in the opening direction by the fuel pressure introduced into the nozzle fuel reservoir and the force that directs the injection hole in the closing direction by the fuel pressure in the pressure chamber. Is what you do. The pressure in the pressure chamber is
This is changed by controlling the opening and closing of a pilot valve stem for discharging high-pressure fuel in the pressure chamber to the low-pressure passage. By changing the pressure in the pressure chamber by the pilot valve stem, the valve member is lifted stepwise. Things.

[0004]

However, in the conventional fuel injection valve disclosed in the above publication (Japanese Unexamined Patent Publication No. 8-326519), the valve member is changed by changing the fuel pressure in the pressure chamber by a pilot valve stem. It was to be lifted in stages. Therefore, when performing fuel injection in a low lift state in which the lift of the valve member is restricted, the restriction position is not reliably determined, and the lift amount varies depending on, for example, temperature, and the required fuel injection amount can be obtained. There was a problem that it disappeared.

The present invention has been made in view of the above circumstances, and has as its object to mechanically determine a restricting position of a lift of a valve member, and to determine a required amount of fuel according to all operating conditions of an engine. It is an object of the present invention to provide a fuel injection device capable of controlling a lift amount of a valve member that can stably obtain an injection rate in a stepwise manner.

[0006]

According to the first aspect of the present invention, there is provided the following:
The movement of the valve member that opens and closes the injection hole is mechanically controlled by the change in the internal pressure of the pressure chamber, and the movement of the lift regulating piston that determines the lift amount is mechanically controlled by the change in the internal pressure of the second pressure chamber. Things. In other words, the position of the valve member is mechanically determined when the lift is stopped (closed), when the lift is low, and when the lift is high. Therefore, there is no problem that the lift amount varies depending on the temperature or the like, and the required fuel injection rate can be stably obtained.

According to a second aspect, the first pressure chamber and the second pressure chamber are connected to each other.
A configuration may be adopted in which the pressure chambers are sequentially changed to sequentially lift the valve member and the lift restriction piston. Claim 3
As means of, when the valve member is in a closed state in which the valve member is seated on a valve seat,
A configuration may be employed in which the position of the lift regulating piston is at a position where the valve member is lifted at a high level.

As means of the fourth aspect, when the position of the lift restricting piston is at the position where the valve member is lifted high, only the valve member can be moved to open and close the injection hole. . The control valve controls the pressures in the first and second pressure chambers to select one of three states: valve closing by a valve member, valve opening at a low lift, and valve opening at a high lift. You may provide so that it may be selected uniformly.

[0009]

Embodiments of the present invention will be described with reference to the drawings. [First Embodiment] A fuel injection device 1 shown in FIG. 1 is inserted into and mounted on an engine head of an engine (not shown), and is configured to directly inject fuel into each cylinder of the engine. The high-pressure fuel discharged from a fuel injection pump (not shown) is accumulated at a predetermined pressure in a pressure accumulation chamber of a pressure accumulation tube (not shown),
The fuel is supplied to the fuel injection device 1. The fuel injection pump adjusts the fuel discharge pressure according to the engine speed, load, intake fuel pressure, intake air amount, cooling water temperature, and the like.

The housing 2 and the valve body 3 of the fuel injection device 1 are fastened with a retaining nut 5 with a tip packing 4 interposed therebetween. The valve member 6 includes a needle 8, a rod 9, and a driving piston 10 from the injection hole 7 side, and the sliding amount thereof is disposed on the valve seat 11 on the injection hole 7 side and on the opposite side of the injection hole 7. Lift control piston 1
2. The needle 8 is reciprocally supported by the valve body 3 and includes a first spring 13.
The valve seat 1 formed on the valve body 3 via the rod 9 by the
One is energized.

The lift restricting piston 12 comes into contact with the drive piston 10 of the lifted valve member 6 to restrict the lift position of the needle 8 to two stages of a low lift and a high lift. The lift restricting piston 12 is urged in the seating direction of the needle 8 by the second spring 14, and from the state of the bottom dead center pressed downward,
By the high-pressure fuel described later, the second spring 14 can be lifted to the top dead center where the second spring 14 is bent as shown in FIG.

The lift amount from the bottom dead center to the top dead center of the lift regulating piston 12, that is, the gap h2 formed at the lower end surface of the lift regulating piston 12 at the time of the top dead center is the maximum lift of the lift regulating piston 12. The gap h1 between the drive piston 10 and the lift restriction piston 12 in a state where the lift restriction piston 12 is at the top dead center and the needle 8 is pressed against the valve seat 11 is the maximum lift (high lift) of the needle 8. Becomes When the lift restricting piston 12 is at the bottom dead center and the needle 8 is pressed against the valve seat 11, a gap (h1 -h2) is formed between the drive piston 10 and the lift restricting piston 12, and this is the gap of the needle 8. It becomes an intermediate regulation lift (low lift).

The valve member 6 sits on the valve seat 11 (closes the injection hole 7) when the first pressure chamber 15 is at a high pressure, and lifts (injects) when the first pressure chamber 15 is at a low pressure. The lift restricting piston 12 lifts the valve member 6 when the second pressure chamber 16 is at a high pressure to enable the valve member 6 to be lifted at a high pressure, and seats when the second pressure chamber 16 is at a low pressure to enable the valve member 6 to be lifted at a low lift. It is to be.

The first pressure chamber 15 is provided so that high-pressure fuel is supplied through a high-pressure passage 17. The first pressure chamber 15 is connected to a low-pressure passage 20 for discharging fuel via a first fuel passage 18 and a control valve 19. When the control valve 19 shuts off the first fuel passage 18 and the low-pressure passage 20, the first pressure chamber 15 becomes high pressure by the high-pressure fuel, and the control valve 19 connects the first fuel passage 18 and the low-pressure passage 20 to each other. Due to the communication, the high-pressure fuel in the first pressure chamber 15 is discharged to a low pressure.

The second pressure chamber 16 is also provided so that high-pressure fuel is supplied through a high-pressure passage 17. Further, the second pressure chamber 16 is also connected to a low-pressure passage 20 for discharging fuel via a second fuel passage 21 and a control valve 19. Then, the control valve 19 shuts off the second fuel passage 21 and the low-pressure passage 20, so that the second pressure chamber 16 becomes high pressure by the high-pressure fuel, and the control valve 19 connects the second fuel passage 21 and the low-pressure passage 20. Due to the communication, the high-pressure fuel in the second pressure chamber 16 is discharged to have a low pressure.

As described above, the pressure in the first pressure chamber 15 and the second pressure chamber 16 is controlled by the control valve 19. As shown in FIG. 1, the control valve 19 closes the low-pressure passage 20 and sets both the first pressure chamber 15 and the second pressure chamber 16 to a high pressure, as shown in FIG. As shown in FIG. 3, a "low lift mode" in which the first fuel passage 18, the second fuel passage 21 and the low pressure passage 20 communicate with each other, and both the first pressure chamber 15 and the second pressure chamber 16 have a low pressure, Second
The “high lift mode” in which only the fuel passage 21 is closed and the first fuel passage 18 and the low-pressure passage 20 communicate with each other to make the first pressure chamber 15 low and the second pressure chamber 16 high. Switch.

The control valve 19 is a component of a solenoid valve 22 mounted on the upper part of the fuel injection device 1.
Is fastened to the upper part of the housing 2 by a nut 23. The solenoid valve 22 includes an armature 24, a body 25, a coil 26, a first coil spring 27, a second coil spring 28, and the like, in addition to the control valve 19.

The control valve 19 can be seated on the housing 2 by the biasing force of the first coil spring 27 to close the low-pressure passage 20, and when the low-pressure passage 20 is closed, the control valve 19 operates in the above-mentioned "valve closing mode". Set. The disc-shaped core 29 provided above the control valve 19 is lifted upward by an exciting attraction force generated when the coil 26 is energized, and abuts on the lower end 30a of the pin 30 to lift H1. The control valve 19 in this state includes the first fuel passage 18 and the second
The fuel passage 21 and the low-pressure passage 20 communicate with each other, and the above-described “low lift mode” is set.

When the value of the current supplied to the coil 26 from the position of the "low lift mode" is further increased, the exciting attraction acting on the core 29 of the control valve 19 becomes large, and the control valve 19 and the pin 30 are connected. As a result, the upper seat portion 19a of the control valve 19 comes into contact with the seat portion 25a of the body 25, and the control valve 19 is lifted by H2. The control valve 19 in this state closes only the second fuel passage 21 and connects the first fuel passage 18 and the low-pressure passage 20, and is set to the “high lift mode” described above. The lift of the control valve 19 from the low lift mode to the high lift mode is H2-H1.

The needle 8 is controlled by controlling the first piston.
The supply of the high-pressure fuel to the first pressure chamber 15 for controlling the opening and closing operation of the fuel supply is performed by the fuel inlet 31, the high-pressure passage 17, the first inlet throttle 32, and the like.
Introduced in order through. First pressure chamber 1 in high pressure state
In order to change 5 to the low pressure state (injection hole 7 opened), the control valve 19 is lifted to open the low pressure passage 20 formed in the housing 2. Then, the high-pressure fuel supplied to the first pressure chamber 15 is sequentially discharged to the first fuel passage 18, the valve fuel chamber 33, and the low-pressure passage 20, and reaches the fuel tank 34.
Here, the flow passage area of the outlet throttle 35 of the low-pressure passage 20 is provided to be larger than the flow passage area of the first inlet throttle 32.

The supply of high-pressure fuel to the second pressure chamber 16, which controls the lift amount of the needle 8 by controlling the lift regulating piston 12, is performed via the fuel inlet 31, the high-pressure passage 17, and the second inlet throttle 36, The pressure is supplied to the pressure chamber 16. Before the driving piston 10 cooperating with the needle 8 lifts, the high-pressure fuel in the high-pressure passage 17 is supplied to the second pressure chamber 16 via the second inlet throttle 36, and the lift-regulating piston 12 is moved by the force. 2 The spring 14 has been bent to reach the top dead center.

In order to change the high pressure state (high lift) of the second pressure chamber 16 to the low pressure state (low lift), the control valve 19 is moved to an intermediate position, that is, the core 29 of the control valve 19, as shown in FIG. Abuts on the lower end 30a of the pin 30 and is stopped with the H1 lifted. In this state, the second fuel passage 21
The high pressure fuel supplied to the second pressure chamber 16 is sequentially discharged to the second fuel passage 21, the valve fuel chamber 33, and the low pressure passage 20 to reach the fuel tank 34.
Here, the flow passage area of the outlet throttle 35 of the low pressure passage 20 is provided to be larger than the flow passage area of the second inlet throttle 36. In the configuration of this embodiment, when the second pressure chamber 16 is changed to the low pressure state, the control valve 19 is set at the intermediate position, so that the first fuel passage 18 and the low pressure passage 20 communicate with each other, and the first pressure chamber 15 is also changed. Change to low pressure state. Therefore, the timing at which the lift restriction piston 12 is operated is synchronized with the operation of the drive piston 10.

As described above, the driving piston 10 and the lift regulating piston 12 are lifted by changing the internal fuel pressure of the first pressure chamber 15 and the second pressure chamber 16, thereby regulating the lift of the needle 8 and the lift amount. It is carried out. The plurality of injection holes 7 are closed by seating the needle 8 on the valve seat 11. The injection rate is variable by providing the injection hole 7 opening at a low lift and the injection hole 7 opening at a high lift.

(Operation of First Embodiment) Next, the operation of the fuel injection device 1 will be described with reference to FIGS. First, fuel is discharged from a fuel injection pump (not shown) and sent to an accumulator (not shown). The high-pressure fuel accumulated at a predetermined fuel pressure in the accumulator of the accumulator tube is supplied to the fuel inlet 31 of the fuel injection device 1.
Supplied to Further, an engine control device (E, not shown)
CU), the control valve 19 according to the operating conditions of the engine.
Is generated and supplied to the coil 26. When the drive current value is low, the control valve 1
9 flexes the first coil spring 27 to lift upward by H1. When the drive current value is high, the control valve 19 deflects the first and second coil springs 27 and 28 by a large excitation attraction force to lift H2.

In the first injection operation mode, a high current flows through the coil 26 of the solenoid valve 22, and the exciting attraction of the coil 26 is large. As shown in FIG. The upper seat portion 19a contacts the seat portion 25a of the body 25. In this state, the second fuel passage 21 is closed, and the first fuel passage 18 and the low-pressure passage 20 communicate with each other.

Then, the first pressure chamber 15 communicates with the low pressure passage 20 via the first fuel passage 18 and the outlet throttle 35.
Since the flow area of the outlet throttle 35 is set larger than that of the first inlet throttle 32, the outflow fuel is more than the inflow fuel,
The fuel pressure in the first pressure chamber 15 starts to decrease. The fuel pressure in the first pressure chamber 15 decreases, and the force in the nozzle hole closing direction, which is the combined force of the set load of the first spring 13 and the force received from the fuel pressure in the first pressure chamber 15, pushes up the needle 8. When it becomes smaller, the needle 8 starts lifting.

At this time, the fuel pressure in the second pressure chamber 16 is set such that the upper seat portion 19a of the control valve 19 is
a in contact with the second fuel passage 21 and
The high pressure state is maintained, and the lift restriction piston 12 is stopped at the top dead center (h2 lift state). Accordingly, the needle 8 is lifted until it comes into contact with the lift regulating piston 12 stopped at the top dead center, and is lifted and stopped by h1 (high lift).

After the predetermined drive pulse time has elapsed, the supply of the drive current to the coil 26 is stopped, the control valve 19 is closed, and the low-pressure passage 20 is closed (the state shown in FIG. 1). Then
The first pressure chamber 15 is supplied with high-pressure fuel from the first inlet throttle 32.
Moves to the high pressure state, and the driving piston 10 cooperating with the needle 8 moves in the valve closing direction. Also at this time, the second pressure chamber 16
Since the high pressure state is maintained, the lift restriction piston 12 remains stopped at the top dead center.

In the second injection operation mode, a low current flows through the coil 26 of the solenoid valve 22, the excitation attraction of the coil 26 is small, and the control valve 19 is moved to the position corresponding to the first lift amount H1 as shown in FIG. The core 29 of the control valve 19 abuts on the lower end 30a of the pin 30 and stops. In this state,
The first fuel passage 18 and the second fuel passage 21 communicate with the low-pressure passage 20.

When the control valve 19 lifts to the first lift amount H1, the fuel pressure in the first pressure chamber 15 decreases, and the set load of the first spring 13 matches the force received from the fuel pressure in the first pressure chamber 15. As a result, the needle 8 is pushed up against the first spring 13 by the fuel pressure supplied from the high-pressure passage 17, the driving piston 10 is lifted via the rod 9, and the needle 8 starts lifting. I do.

At this time, the second pressure chamber 16 communicates with the low pressure passage 20 via the second fuel passage 21 and the outlet throttle 35.
Since the flow area of the outlet throttle 35 is set larger than that of the second inlet throttle 36, the outflow fuel is more than the inflow fuel,
The fuel pressure in the second pressure chamber 16 together with the first pressure chamber 15 decreases. From the load of the second spring 14, the second pressure chamber 1
When the load due to the pressure chamber 6 and the first pressure chamber 15 decreases, the lift regulating piston 12 lifts downward and sits at the bottom dead center. Here, the stopped state is maintained by the load of the second spring 14. The movement amount of the lift restriction piston 12 at this time is h2. For this reason, the needle 8 is lifted until it comes into contact with the lift regulating piston 12 stopped at the bottom dead center, lifted by h1 -h2 and stopped (low lift).

After the predetermined drive pulse time has elapsed, the supply of the drive current to the coil 26 is stopped, the control valve 19 is closed, and the low-pressure passage 20 is closed (the state of FIG. 1). Then
The first pressure chamber 15 is supplied with high-pressure fuel from the first inlet throttle 32.
Moves to the high pressure state, and the driving piston 10 cooperating with the needle 8 moves in the valve closing direction. Further, the second pressure chamber 16 is also shifted to a high pressure state by the high pressure fuel from the second inlet throttle 36,
The lift regulating piston 12 moves to the top dead center. And
When the first pressure chamber 15 is in a high pressure state, the drive piston 10 is pushed down, the needle 8 is seated on the valve seat 11, and the injection hole 7 is completely closed.

When the fuel injection device 1 is mounted on the engine to perform the injection operation, the above-described first and second injection operation modes are switched and the injection hole 7 opening at a low lift and the injection hole opening at a high lift. By providing 7 and 7, it is possible to provide a configuration in which the injection rate can be changed. That is, for example, during high-speed, high-load operation of the engine, the injection rate is increased by the first injection operation mode, and during low-speed, low-load operation, the injection rate is reduced by the second injection operation mode.
This injection mode switching control is performed by an engine control device (EC
The driving current value according to U) can be switched between a high current value and a low current value.

(Effect of First Embodiment) Fuel Injection Apparatus 1
As described above, the switching between the high lift and the low lift can be performed according to the position of the lift restricting piston 12 that is mechanically switched and set. That is, a high lift and a low lift can be reliably obtained, and the switching control of the fuel injection rate can be stably performed, so that high reliability can be obtained.

Further, in a high lift state where the injection rate is increased, the first injection mode is employed. For this reason, the control valve 19 is in the full lift state (the state shown in FIG. 3), the opening flow path area is large, only the valve member 6 is operated, and the lift regulating piston 12 remains stopped, so that the response is high. The needle 8 can be lifted, and high performance can be obtained.

[Second Embodiment] A second embodiment will be described with reference to FIG. FIG. 4 is a sectional view of the fuel injection device 1 according to the second embodiment. Note that the same functional components as in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The fuel injection device 1 according to the second embodiment is different from the first embodiment in that the driving piston 1
0 and the first facing the lift restriction piston 12, respectively.
The fuel pressure in the pressure chamber 15 and the second pressure chamber 16 is
2 to change the lift amount of the needle 8,
The point that the injection rate can be set freely is the same,
The arrangement of the high-pressure fuel in the pressure chamber 15 is different.

Specifically, in the first embodiment, the high-pressure fuel branches off in the high-pressure passage 17 and is introduced into each of the first and second pressure chambers 15 and 16 in parallel. However, in the second embodiment, the high pressure passage 17, the second pressure chamber 16, the valve fuel chamber 3
3. It is connected in series with the first pressure chamber 15, and the introduction of high-pressure fuel into the first pressure chamber 15 is performed via the second pressure chamber 16. The other configuration and operation are the same as those of the first embodiment, and thus the description is omitted.

The fuel injection device 1 of the second embodiment is inferior to the first embodiment in terms of responsiveness because the supply of high-pressure fuel to the first and second pressure chambers 15 and 16 is in series, Since the first inlet throttle 32 shown in the first embodiment is unnecessary, the cost required for manufacturing and adjusting can be reduced.

Third Embodiment A third embodiment will be described with reference to FIG. FIG. 5 is a sectional view of the fuel injection device 1 according to the third embodiment. The same components as those in the above embodiment are denoted by the same reference numerals, and description thereof is omitted. The fuel injection device 1 according to the third embodiment is different from the first embodiment in that the driving piston 1
0 and the first facing the lift restriction piston 12, respectively.
The fuel pressure in the pressure chamber 15 and the second pressure chamber 16 is
2 to change the lift amount of the needle 8,
The point that the injection rate can be freely set is the same, but the position of the second pressure chamber 16 facing the lift restriction piston 12 and the position of the second spring 14 are different.

Specifically, in the third embodiment, while the lift restricting piston 12 is at the top dead center when the needle 8 is closed, the position is determined in the first embodiment. 2 pressure chamber 16 is lift control piston 1
In the third embodiment, the second pressure chamber 16 is arranged on the side of the lift regulating piston 12 opposite to the needle 8, whereas the second spring 14 is arranged on the opposite side of the needle 8. And the second spring 14 moves the needle 8
Located on the side. Therefore, when the needle 8 is closed, the pressure in the second pressure chamber 16 is in a low pressure state, and the lift regulating piston 12 is pressed to the top dead center by the load of the second spring 14.

The operational differences from the first embodiment are as follows.
The high and low pressure states of the second pressure chamber 16 are opposite to those of the first embodiment. The arrangement of the passage around the control valve 19 is such that the passage closed by the control valve 19 when the solenoid valve 22 is stopped is the low-pressure passage 20 in the first embodiment in accordance with the change in the pressure state of the second pressure chamber 16. In the third embodiment, the first fuel passage 18 communicates with the first pressure chamber 15, and the low pressure passage 20 is always open and communicates with the valve fuel chamber 33.

(Injection stop state) When the solenoid valve 22 is stopped, the control valve 19 closes the outlet of the first fuel passage 18, so that the first
The first pressure chamber 15 is brought into a high pressure state by the high pressure fuel from the inlet throttle 32. At this time, the upper seat portion 19 of the control valve 19
a is separated from the seating portion 25a of the body 25, the second fuel passage 21 communicates with the low-pressure passage 20,
The pressure chamber 16 is in a low pressure state. In this state, the load of the second spring 14 is smaller than the downward load by the second pressure chamber 16.
The upward load caused by the lift restriction piston 12 is large.
Is lifted upward.

(During high lift injection) Coil 2 of solenoid valve 22
6, when the control valve 19 is lifted to the position of the first lift amount H1, the first fuel passage 18
Is opened, and the first pressure chamber 15 changes to a low pressure state. Since the lift control piston 12 is stopped at the top dead center while the second pressure chamber 16 is in the low pressure state, the drive piston 10 is stopped at the top dead center.
2. Lift and stop until it touches 2 (high lift).

The predetermined drive pulse time has passed and the coil 26
When the supply of the driving current to the first fuel passage 18 is stopped and the control valve 19 is closed to close the first fuel passage 18 again, the first inlet throttle 32
The first pressure chamber 15 shifts to a high pressure state by the high pressure fuel from
Is seated on the valve seat 11 to close the injection hole 7.

(At the time of low-lift injection) Coil 2 of solenoid valve 22
When the control valve 19 is lifted to the position of the second lift amount H2, the outlet of the first fuel passage 18 is opened, the first pressure chamber 15 changes to a low pressure state, and the driving piston 10 starts moving in the valve opening direction, and the lift of the needle 8 starts. At this time, since the outlet of the second fuel passage 21 is closed by the control valve 19, the second inlet throttle 36
The high pressure fuel moves the second pressure chamber 16 to a high pressure state, and the lift regulating piston 12 overcomes the load of the second spring 14 and moves downward to be seated at the bottom dead center. Therefore, the ascending drive piston 10 abuts on the lift regulating piston 12 seated at the bottom dead center and stops ascending.
The lift amount of the needle 8 is in the regulated lift state of h1 -h2 (low lift).

The predetermined drive pulse time has passed and the coil 26
The supply of the driving current to the first inlet throttle 3 is stopped by closing the control valve 19 to close the first fuel passage 18 again and to communicate the second fuel passage 21 with the low-pressure passage 20 again.
The first pressure chamber 15 shifts to a high pressure state by the high pressure fuel from the second, the driving piston 10 moves in the valve closing direction and the needle 8
Is seated on the valve seat 11 to close the injection hole 7, and the second
The pressure chamber 16 shifts to a low pressure state, and the lift regulating piston 12
Moves upward by the urging force of the second spring 14 and stops at the top dead center.

(Effect of Third Embodiment) In the third embodiment, the second inlet throttle 36 and the second
Since there is a fuel flow through the pressure chamber 16, the second fuel passage 21, the valve fuel chamber 33, and the low-pressure passage 20, the driving piston 10 is suitable for an engine whose injection pressure is relatively low.
The lift is regulated by the load by hydraulic pressure, so that the restriction can be surely made and the responsiveness is improved.

[Fourth Embodiment] A fourth embodiment will be described with reference to FIG. FIG. 6 is a cross-sectional view of a main part of a fuel injection device 1 according to a fourth embodiment. The same components as those in the above embodiment are denoted by the same reference numerals, and description thereof is omitted.

The fourth embodiment is the same as the third embodiment except for the shape of the lift regulating piston 12, and a description thereof will be omitted. In this embodiment, as in the third embodiment, since the second pressure chamber 16 is located above the lift regulating piston 12, there is no need to divide the first pressure chamber 15 from the lower side of the lift regulating piston 12. In view of this, the lower small-diameter sliding portion of the two cylindrical sliding portions of the lift restricting piston 12 in the third embodiment is eliminated. The operation is the third
This is the same as the embodiment, and the description is omitted. In the fourth embodiment, since the shape of the lift regulating piston 12 is simplified, the manufacturing cost can be reduced.

[Other Embodiments] In each of the above embodiments,
Although the example in which the control valve 19 is driven using the electromagnetic valve 22 has been described, the control valve 19 may be driven using another actuator, such as using an electrostrictive actuator instead of the electromagnetic valve 22. The arrangement of the fuel passages, the arrangement of the first spring 13 and the second spring 14, and the like are not limited to the example of the embodiment, but can be appropriately changed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fuel injection device (first embodiment).

FIG. 2 is a sectional view of a main part for describing an operation of the fuel injection device (first embodiment).

FIG. 3 is a cross-sectional view for explaining the operation of the fuel injection device (first embodiment).

FIG. 4 is a sectional view of a fuel injection device (second embodiment).

FIG. 5 is a sectional view of a fuel injection device (third embodiment).

FIG. 6 is a sectional view of a main part of a fuel injection device (fourth embodiment).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection device 3 Valve body 6 Valve member 7 Injection hole 11 Valve seat 12 Lift restricting piston 15 First pressure chamber 16 Second pressure chamber 19 Control valve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G066 AA07 AB02 AC09 BA13 BA46 BA61 CC06U CC08U CC14 CC26 CC40 CC56 CE12 CE22 DA08 DB06 DC00 DC01 DC09 DC14 DC18

Claims (5)

[Claims] (A) a valve member for opening and closing an injection hole; and (b) a valve seat on a fuel upstream side of the injection hole, wherein the valve member is seated on the valve seat so that the injection is performed. A valve body that closes a hole and opens the injection hole when the valve member separates from the valve seat; and (c) lifts when the valve member separates from the valve seat and lifts. A lift restricting piston for switching the lift position of the valve member between a low lift with a small lift and a high lift with a large lift by contacting the valve member with the valve member; and (d) supplying and discharging high-pressure fuel to the valve member. (E) a second pressure chamber for controlling the driving of the lift regulating piston by supplying and discharging high-pressure fuel; and (f) a pressure in the first pressure chamber and the second pressure. By switching the pressure in the room, Fuel injection device comprising a member and a control valve for controlling the movement of the lift regulating piston, the. 2. The fuel injection device according to claim 1, wherein the control valve sequentially changes the first pressure chamber and the second pressure chamber to lift the valve member and the lift regulating piston sequentially. A fuel injection device, comprising: 3. The fuel injection device according to claim 1, wherein when the valve member is in a closed state in which the valve member is seated on the valve seat, the position of the lift restricting piston is a position at which the valve member is lifted high. A fuel injection device, characterized in that: 4. The fuel injection device according to claim 1, wherein when the position of the lift regulating piston is at a position where the valve member is lifted high, only the valve member moves and the valve member moves. A fuel injection device for opening and closing an injection hole. 5. The fuel injection device according to claim 1, wherein the control valve controls the pressure in the first and second pressure chambers to close the valve by the valve member, thereby reducing the valve closing. A fuel injection device characterized by selectively selecting one of three states: valve opening with a lift and valve opening with a high lift.