JP2001227429A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device capable of easily and accurately performing an injection quantity regulation without requiring disassembly and reassembling of precision parts. SOLUTION: This device is provided with an operating chamber 3 for applying pressure of a valve closing direction to a nozzle needle 2 stored into a housing 12 and a valve chamber 5 communicated normally with the operating chamber 3. Within the valve chamber 5, a ball valve 51 for selectively communicating the operating chamber 3 with a fuel supply passage 4 or a return passage 54 is disposed. Between the fuel supply passage 4 and the operating chamber 3, a pressure regulating chamber 7 communicated with the fuel supply passage 4 via a pressure regulating orifice 71 is provided. When the length of a pressure regulating piston 73 is changed and volume of the pressure regulating chamber 7 is changed, pressure of the operating chamber 3 when injection is started or when injection is terminated is changed and injection quantity can be regulated by changing an injection starting time or an injection terminating time.

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 suitably used for a common rail injection system for an internal combustion engine.

[0002]

2. Description of the Related Art In a common rail injection system for an internal combustion engine, a fuel injection device as disclosed in, for example, JP-A-9-184463 is used to inject and supply high-pressure fuel in a common rail to each cylinder. I have. FIG.
FIG. 1A is a view showing the overall configuration of the fuel injection device, in which a nozzle needle 101 for opening and closing an injection hole and a hydraulic piston 102 are accommodated in a lower half portion of a housing 100, and a hydraulic piston 102 is provided above the hydraulic piston 102. A chamber 103 is formed to apply a pressure in the valve closing direction to the nozzle needle 101 and the hydraulic piston 102. The working chamber 103 includes the ball valve 1
The ball valve 104 is driven by a piezo actuator including a piezo stack 106 and a working piston 107.

As shown in FIG. 8B, the valve chamber 105 has a first valve body 108 on the first seat 105a side and a second valve body 1 on the second seat 105b side.
09 is formed by abutting the orifices 110 formed in the first and second valve bodies 108 and 109.
The working chamber 103 (FIG. 8)
(A) is always in communication. Also, the valve chamber 105
Is connected to the return passage 111 via the first sheet 105a.
The fuel supply passage 113 communicates with the fuel supply passage 113 via the second sheet 105b and the passage 112.

In an initial state where the piezo stack 106 is contracted, the ball valve 104 moves the upper first seat 10.
5a, the nozzle needle 101 is closed by the fuel pressure flowing from the fuel supply passage 113 into the working chamber 103 via the valve chamber 105. Next, the piezo stack 106 is extended and the working piston 107 is moved to the ball valve 10.
When 4 is pressed against the second seat 105b, the working chamber 103 is conducted to the return passage 111, the pressure drops, and the nozzle needle 101 opens.

[0005]

By the way, in the common rail injection system, it is required to accurately inject and supply an amount of fuel to each cylinder according to the operation state of the internal combustion engine. For this reason, it is necessary to adjust the variation of the injection amount caused by the manufacturing variation of the constituent members after the assembly of the fuel injection device. In the conventional fuel injection device, the orifice member 114 forming the orifice 110a reaching the working chamber 103 is required. The injection amount is adjusted by rearranging (see FIG. 8B).

However, since the orifice member 114 is normally press-fitted into the second valve body 109, the second valve body 10 must be replaced to replace the orifice 110a.
9 must also be replaced. For this reason, the position of the second seat 105b moves due to the processing tolerance, and the ball valve 10
The lift amount of No. 4 changes. FIG. 9 shows the effect of the change in the lift amount on the lift characteristics of the nozzle needle 101.
(A) (piezo displacement and ball valve displacement are shown in FIG. 8)
A downward displacement is defined as positive). Also, the change in the diameter of the orifice 110a due to the deformation due to the press-fitting may be caused by the fact that the orifice 11
This is a factor that changes the flow rate of the fuel passing through Oa, and it is not easy to adjust the injection amount.

On the other hand, when the orifice member 114 is not press-fitted, fuel flows not only through the orifice 110a but also through the gap with the second valve body 109, so that the total flow rate changes. As shown in b), the injection characteristics change greatly. Furthermore, regardless of the presence or absence of press fit,
The retaining nut 116 at the upper end of the housing 100 is to be re-tightened.
There is a possibility that the amount of deformation of the second valve body 109 varies and the seat position changes. Although the deformation amount is on the order of several microns, the lift amount of the ball valve 104 is also set on the order of microns, so that the influence on the injection characteristics is not small.

As described above, in the conventional configuration, even if the orifice member 114 is rearranged, a desired injection characteristic cannot be easily obtained. In addition, as a method of adjusting the injection characteristics, a method of changing the length of the hydraulic piston 102 to change the volume of the working chamber 103 is considered. For example, if the volume of the working chamber 103 is increased, the injection start timing is delayed. However, similarly, since the injection end time is also late, the injection amount itself does not change much. Further, the point that the main part needs to be disassembled is the same as the above-described conventional configuration, and is not an appropriate means for adjusting the injection amount.

The present invention has been made in view of the above circumstances, and has as its object to disassemble precision parts such as valve parts.
An object of the present invention is to provide a fuel injection device that does not require reassembly and that can easily and accurately adjust an injection amount.

[0010]

According to a first aspect of the present invention, there is provided a fuel injection device which accommodates a nozzle needle for opening and closing an injection hole in a housing and applies a pressure to the nozzle needle in a valve closing direction. And a valve body disposed in a valve chamber that is always in communication with the working chamber and selectively connecting the working chamber to a high-pressure passage or a low-pressure passage according to a seat position. A variable-volume pressure regulating chamber communicating with the high pressure passage via an orifice is provided in the middle of the passage connecting the high pressure passage and the working chamber. By changing the volume of the pressure regulating chamber, injection is performed. The injection amount is adjusted by controlling the pressure of the working chamber at the start or end of the injection.

In the above structure, when the seat position is switched by driving the valve body, the working chamber communicates with the high-pressure passage or the low-pressure passage to increase or decrease the pressure, whereby the nozzle needle opens and closes. At this time, if the pressure regulating chamber is provided between the high pressure passage and the working chamber, the orifice delays the flow of fuel from the high pressure passage into the pressure regulating chamber. And lowers the pressure in the working chamber in communication therewith. The amount of the change differs depending on the volume of the pressure regulating chamber, and only the injection start timing or the injection end timing can be changed depending on the arrangement of the pressure regulating chamber. Therefore, by changing the volume of the pressure regulation chamber, it is possible to change the injection start timing or the injection end timing to adjust the injection amount.

According to a second aspect of the present invention, the pressure regulating chamber is provided in a passage connecting the high pressure passage and the working chamber without passing through the valve chamber. In the configuration in which the pressure regulating chamber communicates directly with the working chamber as described above, at the start of injection in which the working chamber communicates with the low-pressure passage, the fuel flow rate flowing from the pressure regulating chamber into the working chamber is reduced by the pressure regulating chamber. It changes depending on the volume of the chamber. That is, if the volume of the pressure regulating chamber is small, the pressure drops rapidly, so that the flow rate becomes small, the pressure in the working chamber largely decreases, and the injection start timing is advanced. At the end of the injection in which the working chamber communicates with the high-pressure passage, there is no large difference due to the volume of the pressure regulating chamber, and the pressure of the working chamber is increased by the fuel flowing from the valve chamber. The time does not change. Therefore, the injection amount can be adjusted by changing only the injection start timing.

According to a third aspect of the present invention, the pressure regulating chamber is provided in a passage connecting the high pressure passage and the valve chamber. With this configuration, at the start of injection, the pressure between the high-pressure passage and the valve chamber is shut off, so that the pressure change in the working chamber is not affected by the volume of the pressure regulation chamber, and the injection start timing does not change. On the other hand, at the end of the injection, the pressure drop in the pressure regulating chamber changes according to its volume, so that the fuel flow rate flowing into the working chamber via the pressure regulating chamber and the valve chamber changes. That is, when the volume of the pressure regulating chamber is small, the pressure drops rapidly, so that the flow rate becomes small, the pressure rise in the working chamber becomes gentle, and the injection end timing is delayed. Therefore, the injection amount can be adjusted by changing only the injection end timing.

Specifically, one end of the pressure regulating chamber is opened in the housing wall, and a piston member is inserted and fixed from the outside to the opening to seal the pressure regulating chamber. It can be. In this configuration, the volume of the pressure regulation chamber can be easily changed by changing the length of the piston member, and there is no need to remove other members for rearrangement, and the injection amount can be easily adjusted. Moreover, it can be performed with high accuracy.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1A is an overall configuration diagram of a fuel injection device used in a common rail fuel injection system of an engine, and FIG. 1B is a top view thereof. FIG.
(A) In the middle, the fuel injection device 1 has a cylindrical upper housing 1.
1 and a lower housing 12 screwed to the lower end thereof. A cylinder is formed in the hydraulic piston body 13a and the nozzle body 13b disposed in the lower housing 12, and the hydraulic piston 21 and the nozzle needle 2 are slidably housed therein. are doing. The working chamber 3 is formed above the hydraulic piston 21, and applies a hydraulic pressure in the valve closing direction (downward) to the nozzle needle 2 via the hydraulic piston 21. When the hydraulic pressure in the working chamber 3 decreases, the hydraulic piston 21 and the nozzle needle 2 move upward, the injection hole 22 is opened, and fuel is injected from the fuel pool 23 on the outer periphery of the middle part of the nozzle needle 2. When the hydraulic pressure in the working chamber 3 rises and the hydraulic piston 21 descends against the spring force of the spring 24 and the hydraulic pressure that the nozzle needle 2 receives in the valve opening direction, the nozzle needle 2 is pressed by the injection hole 22 and closed. Give a valve.

A fuel supply passage 4 which is a high-pressure passage is formed in the upper and lower housings 11 and 12 in a vertical direction.
The lower end is in the fuel reservoir 23 and the upper end is in the upper housing 1.
It communicates with the inside of the fuel introduction pipe 42 on the upper side of the first part. The fuel introduction pipe 42 is connected to a common rail (not shown) in which high-pressure fuel is accumulated. Further, the fuel supply passage 4 is connected to the lower housing 1.
2, and communicates with the valve chamber 5 through the communication passage 41. The valve chamber 5 is formed at an abutting portion between the hydraulic piston body 13a and the distance piece 14 thereabove, and accommodates a ball valve 51 as a valve body. Is switched. The working piston 62 is provided in the upper housing 1.
The piezo stack 61 is provided in contact with the piezo stack 61 and moves with the expansion and contraction of the piezo stack 61 to transmit the displacement to the ball valve 51. These piezo stacks 6
1 and the working piston 62 constitute a piezo actuator as a drive unit.

FIG. 2A is an enlarged view of the vicinity of the valve chamber 5. A rod 62 a is integrally provided on a lower end surface of the working piston 62, extends into a cylinder penetrating the distance piece 14, and contacts an upper end of the ball valve 51.
The valve chamber 5 has a tapered first seat 5a at the upper end,
The tapered second sheet 5 is formed at the lower end to which the communication passage 41 is connected.
b, and the first sheet 5a includes the distance piece 14
And a return passage 54 (see FIG. 1) as a low-pressure passage through a passage (not shown) along the inner peripheral wall of the cylinder.
The return passage 54 extends vertically in the upper housing 11 (FIG. 1A), and reaches a fuel outlet pipe 55 (FIG. 1B) in an upper portion of the upper housing 11. Valve chamber 5
A passage 52 formed in the distance piece 14 and the hydraulic piston 13a is opened to the side of the, and the passage 52 communicates with the working chamber 3 via an orifice 53. Thereby, the working chamber 3 selectively communicates with the return passage 54 or the fuel supply passage 4 according to the seat position of the ball valve 51, and increases or decreases the hydraulic pressure acting on the nozzle needle 2. The working piston 62 is urged upward by a disc spring 63 provided in contact with the lower end surface.
A spacer for adjusting the set load is provided below the reference numeral 3.

Next, regarding the characteristic portions of this embodiment,
First, a description will be given based on the schematic configuration diagram of FIG. FIG. 3 is a simplified view of FIG. 1, and some components such as a housing are omitted. In FIG. 3, the fuel supply passage 4 branches at a first branch point 4 a and communicates with a pressure regulating chamber 7 via a pressure regulating orifice 71. The pressure regulating chamber 7 also has an orifice 72.
And is communicated with the working chamber 3. The fuel supply passage 4 is
Further branching at a second branching point 4b downstream of the first branching point 4a,
The above-mentioned communication path 41 has reached the valve chamber 5.
A pressure adjusting piston 73 is inserted into the upper part of the pressure adjusting chamber 7 via a seal member 74, and the volume of the pressure adjusting chamber 7 can be changed by changing its length.

More specifically, in FIG. 2A, a small-diameter portion provided in the upper housing 11 and the distance piece 14 in the up-down direction is a pressure regulating chamber 7, and is located above the distance piece 14 shown in FIG. The pressure regulating orifice 71 formed on the end face communicates with the first branch point 4 a of the fuel supply passage 4. An insertion hole 62b into which the rod 62a of the working piston 62 is inserted is formed at a substantially central portion of the distance piece 14, and communicates with the return passage 54 via a groove 54a provided on the upper end surface. In FIG. 2A, an orifice 72 is formed below the pressure regulating chamber 7, and reaches the working chamber 3 through a lower end surface of the distance piece 14 and a passage 75 formed in the hydraulic piston body 13a. The upper end of the pressure adjustment chamber 7 is bent to the side and expanded in diameter, and is opened on the side surface of the upper housing 11. The pressure adjustment piston 73 is screw-fixed to this opening via a seal member 74. The pressure regulation chamber 7 is sealed. By changing the pressure adjusting piston 73 to one having a different length, the volume of the pressure adjusting chamber 7 can be made variable.

The operation of the fuel injection device having the above configuration will be described with reference to a time chart of FIG. In the state shown in FIG.
The piezo stack 61 is contracted, the ball valve 51 closes the upper first seat 5 a, and the fuel supply passage 4 and the working chamber 3 communicate with each other via the valve chamber 5. At this time, the pressure in the working chamber 3 and the pressure regulating chamber 7 is the same as the pressure in the common rail and is high, and the hydraulic piston 21 and the nozzle needle 2 are pressed downward, so that no fuel is injected. Next, a piezo stack 6 is driven by a drive circuit (not shown).
When 1 is extended, the rod 62a of the working piston 62 pushes down the ball valve 51 to open the first seat 5a (point in FIG. 4a: the downward displacement in FIG. 3 is positive), and then closes the second seat 5b. . As a result, the working chamber 3 communicates with the low-pressure return passage 54, and the pressure in the working chamber 3 decreases,
When the pressure becomes equal to or lower than the predetermined pressure, the nozzle needle 2 is lifted and fuel is injected.

Here, the working chamber 3 communicates with the pressure regulating chamber 7 through the orifice 72 and the valve chamber 5 through the orifice 53.
2 and the flow rate flowing out of the orifice 53. On the other hand, since the pressure regulating orifice 71 exists between the pressure regulating chamber 7 and the fuel supply passage 4, immediately after the first sheet 5a is opened, the flow of fuel into the pressure regulating chamber 7 is delayed and the pressure increases. descend. The amount of the pressure drop largely depends on the volume of the pressure regulating chamber 7. For example, when the volume of the pressure regulating chamber 7 is small, the pressure drops rapidly, so that the flow rate passing through the orifice 72 decreases. Therefore, the pressure drop is large as compared with the case where the volume of the pressure regulation chamber 7 is large, and the injection start timing (point b in FIG. 4) is advanced.

Thereafter, the pressure in the pressure regulating chamber 7 rises and stabilizes at a saturating pressure at which the amount of inflow from the pressure regulating orifice 71 and the amount of outflow to the orifice 72 are balanced. The saturating pressure is determined by the diameters of the pressure adjusting orifice 71, the orifice 72, and the orifice 53, and can be brought close to the common rail pressure by appropriately selecting these three orifice diameters. The fuel supply passage 4 extending from the first branch point 4a to the fuel reservoir 23 by installing the pressure regulating orifice 71.
The back pressure of the nozzle needle 2 can be adjusted without lowering the fuel pressure inside the nozzle needle 2 without lowering the injection pressure. Further, by selecting the diameter of the pressure adjustment orifice 71, the sensitivity of the change in the injection amount with respect to the change in the volume of the pressure adjustment chamber 7 can be adjusted. The smaller the orifice diameter, the higher the sensitivity.
That is, the injection amount can be largely changed with respect to the volume change. When the orifice diameter is large, the sensitivity is deteriorated and the fuel pressure toward the injection hole 22 is greatly reduced. However, when the orifice diameter is too small, the sensitivity is too sensitive and adjustment is difficult. Therefore, when selecting the diameter of the pressure adjusting orifice 71, it is preferable to set the diameter as large as possible within a range that does not adversely affect the injection and within a range where the required injection amount can be adjusted. Good.

Next, when the piezo stack 61 is contracted again, the working piston 62 moves upward, and the ball valve 5
1 moves upward due to the oil pressure of the high-pressure fuel flowing from the communication passage 41 and the fuel pressure flowing from the valve chamber 5 to the return passage 54 to close the first seat 5a (FIG. 4).
c point). At this time, if the volume of the pressure regulating chamber 7 is small, the pressure rapidly rises due to the fuel passing through the pressure regulating orifice 71, so that the flow rate passing through the orifice 72 increases,
There is no much difference from the case where the volume of the pressure regulation chamber 7 is large. Even if the flow rate is small, the pressure in the working chamber 3 is quickly increased by the fuel flowing through the communication passage 41 and the valve chamber 5, so that there is almost no difference in pressure increasing speed due to the volume of the pressure regulating chamber 7. . In other words, the injection end timing is almost the same,
Since only the injection start timing changes, the injection amount can be adjusted using this.

Therefore, according to the present embodiment, the working chamber 3
By changing the volume of the pressure regulating chamber 7 provided between the fuel supply passage 4 and the fuel supply passage 4, the injection start timing is changed and the injection amount can be easily adjusted. Further, by changing the length of the pressure adjusting piston 73, the volume of the pressure adjusting chamber 7 can be easily changed, and disassembly and reassembly are not required. Well done.

FIG. 5 shows a second embodiment of the present invention, in which the structure of a pressure adjusting piston 73 for changing the volume of the pressure adjusting chamber 7 is changed. The other basic configuration is the same as that of the first embodiment, and is not shown. In FIG. 5, a pressure adjusting piston 73 includes a main body 73 a that is screwed to a screw at an upper end opening of the pressure adjusting chamber 7 with a screw formed on the outer periphery of a lower end, and an outer periphery around an upper half of the main body 73 a. It consists of a cylindrical locking nut 73b to be inserted. Lock nut 73
b, the screw portion on the inner periphery of the upper end portion is screwed with the screw portion on the outer periphery of the upper end portion of the main body portion 73a, and the lower half portion made of the elastic member is used as the seal portion 73c, and the outer periphery of the middle portion of the main body portion 73a and the reverse of the housing 11 are provided. It is in close contact with the inner wall of the tapered opening.

In this configuration, when the volume of the pressure regulating chamber 7 is changed, the main body 73a is rotated while the locking nut 73b is loosened, and the locking is stopped when the pressure regulating chamber 7 has a desired volume. Tighten the nut 73b. As a result, the seal portion 73c of the locking nut 73b is deformed, and the opening of the inverted tapered housing 11 and the main body portion 73a are formed.
Between them to ensure a seal.

According to the above configuration, it is not necessary to replace the pressure adjusting chamber 7 with a pressure adjusting piston 72 having a different length in order to change the volume of the pressure adjusting chamber 7, and the number of parts can be reduced. In addition, the work of adjusting the volume is reduced, and the injection amount can be easily adjusted.

FIG. 6 shows a schematic configuration diagram of a third embodiment of the present invention. The basic configuration is the same as that of the first embodiment, and the following description will focus on the differences. In the present embodiment, a communication passage 4 that communicates the fuel supply passage 4 with the valve chamber 5
A pressure regulating chamber 7 is provided in the middle of 1, and a pressure regulating orifice 71 is provided upstream of the pressure regulating chamber 7. The structure in which the pressure adjustment piston 73 is screwed into the upper part of the pressure adjustment chamber 7 via the seal member 74 is the same as that of the first embodiment, and the adjustment of the pressure adjustment piston 73 is performed by changing the length of the pressure adjustment piston 73. The volume of the pressure chamber 7 can be changed.

The operation of the fuel injection device having the above configuration will be described with reference to a time chart of FIG. When the piezo stack 61 is extended from the initial state shown in FIG. 6, the ball valve 51 moves downward to open the first seat 5a (FIG. 7A).
Point), the second sheet 5b is closed. As a result, the fuel in the working chamber 3 flows out through the orifice 53 to the low-pressure return passage 54, and the pressure in the working chamber 3 decreases. When the pressure in the working chamber 3 becomes equal to or lower than the predetermined pressure, the nozzle needle 2 starts lifting and fuel is injected (point b in FIG. 7).

Here, in the present embodiment, the pressure regulating chamber 7 is provided between the fuel supply passage 4 and the valve chamber 5, and the communication passage 4 is provided.
Since the second sheet 5b reaching 1 is closed, the pressure drop speed of the working chamber 3 is not affected by the pressure regulating chamber 7, and the pressure of the pressure regulating chamber 7 does not change. That is, the injection start timing is the same as in the conventional configuration having no pressure regulation chamber 7, and does not change depending on the volume of the pressure regulation chamber 7. Next, when the piezo stack 61 is contracted, the ball valve 51 moves upward to open the second seat 5b and close the first seat 5a (FIG. 7c).
point). As a result, fuel flows into the working chamber 3 via the pressure regulating chamber 7 and the valve chamber 5, and the pressure in the working chamber 3 starts to increase.

At this time, the flow of fuel into the pressure adjustment chamber 7 is delayed due to the presence of the pressure adjustment orifice 71, and the pressure in the pressure adjustment chamber 7 is greatly reduced instantaneously. The amount of the pressure drop depends on the volume of the pressure regulating chamber 7, and as shown in the figure, when the volume is large, the pressure drop is small, and when the volume is small, the pressure drop is large. For this reason, the flow rate of fuel flowing into the working chamber 3 through the orifice 53 changes, and when the volume of the pressure regulating chamber 7 is large, the pressure in the working chamber 3 quickly rises to reach a predetermined pressure, and the nozzle needle 2 starts to descend (point d in FIG. 7).
On the other hand, when the volume of the pressure regulating chamber 7 is small,
Of the nozzle needle 2 is slowed down (point e in FIG. 7).

Therefore, according to the configuration of the present embodiment, only the injection end timing can be changed by changing the volume of the pressure regulation chamber 7, and the injection amount can be adjusted easily and accurately. Further, the configuration can be simplified as compared with the first embodiment.

As described above, according to the present invention, the apparent flow rate can be reduced by providing the pressure regulating chamber 7 upstream of the working chamber 3 and changing the pressure, instead of changing the orifice diameter as in the prior art. By changing the pressure, the pressure in the working chamber 3 can be controlled. Accordingly, the injection amount can be adjusted by changing the injection start timing by a simple method of changing the length of the pressure adjustment piston 72 to change the volume of the pressure adjustment chamber 7. In addition, since the disassembly and reassembly for replacing the orifice member are not required as in the related art, the injection amount can be easily adjusted with high accuracy.

In each of the above embodiments, a piezo actuator having a piezo stack is used as a driving unit.
The present invention is not limited to this, and an actuator using a solenoid may be employed.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment of the present invention, wherein FIG. 1A is an overall configuration diagram of a fuel injection device, and FIG. 1B is a top view of the fuel injection device.

FIG. 2A is a partial sectional view of the fuel injection device taken along the line AA in FIG. 1B, and FIG. 2B is an overall perspective view of the distance piece according to the first embodiment.

FIG. 3 is a diagram illustrating a schematic configuration of a fuel injection device according to the first embodiment.

FIG. 4 is a time chart for explaining the operation of the first embodiment.

FIG. 5 is a sectional view of a main part of a fuel injection device according to a second embodiment of the present invention.

FIG. 6 is an overall schematic diagram of a fuel injection device showing a third embodiment of the present invention.

FIG. 7 is a time chart for explaining the operation of the third embodiment.

FIG. 8A is an overall sectional view of a conventional fuel injection device,
(B) is a sectional view of a main part of (a).

9A and 9B are time charts for explaining the operation of the conventional fuel injection device, in which FIG. 9A shows the effect when the lift amount changes, and FIG. 9B shows the effect when the fuel flow rate changes. FIG.

[Explanation of symbols]

 Reference Signs List 1 fuel injection device 11 upper housing 12 lower housing 14 distance piece 2 nozzle needle 21 hydraulic piston 22 injection hole 23 fuel reservoir 3 working chamber 4 fuel supply passage (high pressure passage) 41 communication passage 5 valve chamber 51 ball valve (valve body) 52 Passage 53 Orifice 54 Return passage (low pressure passage) 61 Piezo stack 62 Working piston rod 7 Pressure regulating chamber 71 Pressure regulating orifice (orifice) 72 Orifice 73 Pressure regulating piston

Claims (4)

[Claims] 1. A working chamber for accommodating a nozzle needle for opening and closing an injection hole in a housing and for applying a pressure in a valve closing direction to the nozzle needle, and a seat position disposed in a valve chamber which is always in communication with the working chamber. A fuel valve that selectively connects the working chamber to a high-pressure passage or a low-pressure passage according to the above-described configuration, and switches a seat position of the valve body to increase or decrease the pressure in the working chamber. A variable pressure regulating chamber communicating with the high-pressure passage via an orifice is provided in the passage connecting the pressure chamber and the working chamber, and by changing the volume of the pressure regulating chamber, at the start of injection or at the end of injection. A fuel injection device for controlling the pressure in the working chamber to adjust the injection amount. 2. The fuel injection device according to claim 1, wherein the pressure regulation chamber is provided in a passage connecting the high pressure passage and the working chamber without passing through the valve chamber. 3. The fuel injection device according to claim 1, wherein the pressure regulation chamber is provided in a passage connecting the high pressure passage and the valve chamber. 4. An end of the pressure regulating chamber is opened in the housing wall, and a piston member is inserted and fixed from the outside into the opening to seal the pressure regulating chamber and change the length of the piston member. The fuel injection device according to any one of claims 1 to 3, wherein the volume of the pressure regulation chamber is made variable.