JPH08232797A - Fuel injector - Google Patents

Abstract

PURPOSE: To enable both intermediate member and fixed orifice to be liquid- tightly connected to each other by pushing and crushing so as to deform the intermediate member unit the upper end surface of a nozzle holder and the bottom end surface of the body of a three-way electromagnetic valve come in mutual contact with each other, and a fixed orifice receiving reaction from the intermediate member is placed in tightly attached fixture to the bottom surface of the body. CONSTITUTION: A longitudinal long hole 16 is formed in a nozzle holder 5, in a fuel injector whose initial injection rate is lowered by decreasing the back pressure of a hydraulic piston 6 gradually at the time of starting fuel injection, and the hydraulic piston 6 is fittingly inserted in long hole 16 and an intermediate member 17 and a fixed orifice 8 are received in its upper part. Thereby a pressure chamber 18 is formed between the hydraulic piston 6 and the fixed orifice 8. While the intermediate member 17 made of cold rolled steel plate, etc., elastically deformable at the time of tightly clamping a body 25 against the nozzle holder 5 is subjected to compressive deformation, the nozzle holder 5 and the body 25 are tightly attached and fixed to each other so that such a connection as including no fuel leakage may be made practicable.

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 injecting high pressure fuel into a diesel engine.

[0002]

2. Description of the Related Art Conventionally, there is a fuel injection device for accumulating high pressure fuel in a kind of surge tank called a common rail and injecting the accumulated high pressure fuel into a diesel engine. In this fuel injection device, there is known a technique of reducing the initial injection rate by discharging the back pressure (high pressure fuel) of the hydraulic piston through an orifice formed in the movable valve body at the start of fuel injection.

However, when pilot injection is performed prior to the main injection, if the main injection is started after the pilot injection and before the movable valve body returns to the initial position,
Since the high pressure fuel flows out through the outer periphery of the movable valve body,
The initial injection rate of the main injection becomes high. When the main injection is performed just before the movable valve body returns, the main injection is performed with the movable valve body returning to the initial position, or the movable valve body has not returned to the initial position. The main injection is performed in. Therefore, there is a problem that the initial injection rate becomes low or high, that is, so-called asymmetrical injection.

Therefore, the present applicant has filed Japanese Patent Application No. 6-2721.
In No. 40, a fuel injection device that can perform stable injection while lowering the initial injection rate of main injection was proposed. In this fuel injection device, as shown in FIG. 12, a throttle member 110 having an orifice 100 is housed in a housing 210 formed in a nozzle holder 200, and a bottom surface 211 of the housing 210 and a body of the three-way solenoid valve 300 are housed. It is closely fixed to the end face 310. This allows
A pressure chamber 220 is formed between the hydraulic piston 400 fitted into the nozzle holder 200 and the throttle member 110, and the pressure chamber 220 is formed in the high pressure passage 320 or the low pressure passage 330 which is switched by the three-way solenoid valve 300 through the orifice 100. Communicated.

According to this structure, since the position of the throttle member 110 is fixed, all the high-pressure fuel flowing out of the pressure chamber 220 at the start of fuel injection passes through the orifice 100.
Therefore, the outflow rate of the fuel flowing out of the pressure chamber 220 is suppressed, and the back pressure of the hydraulic piston 400 slowly decreases, so that the initial injection rate becomes low. Even when the pilot injection is performed prior to the main injection, the pressure chamber 2
When the fuel is discharged from 20, the orifice 100
Therefore, the asymmetrical injection in which the initial injection rate of the main injection becomes low or high does not occur.

[0006]

However, in the fuel injection device of the prior application, the throttle member 110 is mounted on the bottom surface 21 of the housing portion 210.
1 and the body end surface 310 of the three-way solenoid valve 300 are closely fixed. Therefore, when the dimensional accuracy of the diaphragm member 110 or the housing portion 210 is low, for example, the length of the diaphragm member 110 is longer than the depth of the housing portion 210 and the diaphragm member 1
When a step is generated between the end surface of the nozzle holder 10 and the end surface of the nozzle holder 200, the high pressure passage 2 formed in the nozzle holder 200
A minute gap is generated between the high pressure passage 320 formed in the three-way solenoid valve 300 and the fuel cell 30.

On the other hand, from the depth of the storage portion 210, the diaphragm member 1
If the length of 10 is shorter, the throttle member 110 cannot be tightly fixed between the bottom surface 211 of the storage portion 210 and the body end surface 310 of the three-way solenoid valve 300, and the throttle member 110 is stored inside the storage portion 210. Since it moves, it adversely affects the injection start timing and the injection end timing.

Therefore, the diaphragm member 1 is formed by the method of the prior application.
When fixing 10, the length of the diaphragm member 110 and the depth of the storage portion 210 need to be controlled with an accuracy of several microns, so that the number of processing steps (processing time) is significantly increased and the cost is increased. There is a problem of inviting. The present invention has been made based on the above circumstances, and an object thereof is to provide a fuel injection device capable of significantly reducing the number of processing steps.

[0009]

In order to achieve the above object, the following constitution is adopted for each claim. According to a first aspect of the present invention, there is provided a valve main body having a high-pressure introduction passage for introducing high-pressure fuel, and a passage switching means formed with the valve main body in the axial direction to form a high-pressure passage connected to the high-pressure introduction passage. And a throttle member housed in a recess opening in the valve body or an assembly surface of the passage switching means and having an orifice formed to connect the valve body side and the passage switching means side, and the valve body. And a connecting means for axially connecting the passage switching means and the throttle member, and is housed in the recess together with the tightening force of the fastening means to receive the tightening force of the fastening means and the assembly surface of the passage switching means. And an intermediate member that compressively deforms until they come into close contact with each other.

According to a second aspect of the present invention, in the fuel injection device according to the first aspect, the throttle member is set so that the entire length of the throttle member accommodated in the recess is shorter than the depth of the recess.

According to a third aspect of the present invention, a valve main body having a high pressure introducing passage for introducing high pressure fuel, and a high pressure passage axially combined with the valve main body to be connected to the high pressure introducing passage are formed. A passage switching means, and a throttle member housed in a recess opening in the valve body or an assembly surface of the passage switching means, and having an orifice formed to connect the valve body side and the passage switching means side. A fastening means for fastening the valve body and the passage switching means in an axial direction is provided, and the throttle member secures a predetermined clearance between the valve body and the assembly surface of the passage switching means. It is fixed in the recess.

According to a fourth aspect, in the fuel injection device according to the third aspect, the throttle member is screwed to an inner peripheral surface of the recess. In claim 5,
The fuel injection device according to claim 3 is characterized in that the throttle member is press-fitted into the recess.

According to a sixth aspect, in the fuel injection device according to any one of the first to fifth aspects, the passage switching means is provided with a communication passage communicating with the orifice and a low pressure passage communicating with a low pressure side. A passage switching valve for switching between the high-pressure passage and the low-pressure passage and connecting one of them to the communication passage is built in, and the valve body is provided with an injection hole that communicates with the high-pressure introduction passage, and opens and closes this injection hole. The valve body is slidably inserted into the valve body, and a pressure chamber for introducing back pressure through the orifice is formed in the rear end surface of the valve body. When the back pressure introduced into the pressure chamber is equal to or lower than the valve opening pressure, the valve is opened. A body opens the injection hole, and when the back pressure introduced into the pressure chamber is equal to or higher than the valve closing pressure, the valve body closes the injection hole.

[0014]

[Operation and effect of the invention]

(Claim 1) By fastening the valve body and the passage switching means in the axial direction by the fastening means, the intermediate member housed in the recess together with the throttle member is compressed, and the assembly surface of the valve body and the passage switching means is compressed. It deforms until they come into close contact with each other. This allows
With the throttle member fixed, the high pressure introduction passage provided in the valve body and the high pressure passage provided in the passage switching means are fluid-tightly connected. In the present invention, since the dimensional error between the recess and the diaphragm member can be absorbed by the deformation of the intermediate member, it is necessary to control the depth of the recess and the total length of the diaphragm member housed in the recess with an accuracy of several microns. The number of processing steps can be reduced significantly.

(Claim 2) In order that the valve body and the assembling surfaces of the passage switching means may come into close contact with each other due to the deformation of the intermediate member,
It goes without saying that the entire length of the diaphragm member housed in the recess is set shorter than the depth of the recess.

(Claim 3) The throttle member may be directly fixed to the recess instead of being tightly fixed between the valve body and the passage switching means. In this case, if a predetermined clearance is secured between the end surface of the throttle member fixed in the recess and the mounting surface of the valve body or the passage switching means (that is, the total length of the throttle member housed in the recess). Is shorter than the depth of the recess),
The assembling surfaces of the valve body and the passage switching means are brought into close contact with each other, so that the high-pressure introduction passage provided in the valve body and the high-pressure passage provided in the passage switching means are fluid-tightly connected.

(Claims 4 and 5) As a method for fixing the throttle member in the recess, a screw screwing with each other is formed on the inner peripheral surface of the recess and the outer peripheral surface of the diaphragm member, and the two are screwed together. The diaphragm member can be fixed in the recess by. Alternatively, it can be fixed by pressing into the recess.

(Claim 6) The passage switching means selectively switches between the high pressure passage and the low pressure passage by means of a passage switching valve incorporated therein, and connects one of them to the communication passage. Since this communication passage communicates with the pressure chamber formed in the valve body through the orifice, for example, when the high pressure passage is connected to the communication passage by the passage switching means, the high pressure fuel introduced into the high pressure introduction passage of the valve body is communicated. Are introduced into the pressure chamber through the high pressure passage, the communication passage, and the orifice.

On the other hand, when the low-pressure passage is connected to the communication passage by the passage switching means, the pressure chamber communicates with the low-pressure passage through the orifice and the communication passage, so that the high-pressure fuel in the pressure chamber passes through the orifice and the communication passage. Is discharged to. Therefore, when the high-pressure fuel is discharged from the pressure chamber and the back pressure acting on the rear end face of the valve element falls below the valve opening pressure, the valve element opens the injection hole and the high-pressure fuel is injected from the injection hole to the pressure chamber. When the high pressure fuel is introduced and the back pressure acting on the rear end surface of the valve body becomes equal to or higher than the valve closing pressure, the valve body closes the injection hole and ends the fuel injection.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the fuel injection device of the present invention will be explained based on the drawings. (First Embodiment) FIG. 1 is an enlarged cross-sectional view of a main part including a pressure chamber. The fuel injection device 1 (see FIG. 4) of the present embodiment is connected to an introduction pipe (not shown) branched from a common surge tank (not shown) and attached to each cylinder of a diesel engine (not shown). ing. As shown in FIG. 4, this fuel injection device 1 includes a nozzle body 2, a needle 3 (see FIG. 5), a tip packing 4, a nozzle holder 5, a hydraulic piston 6, and a three-way solenoid valve 7 (passage switching means of the present invention). , And the fixed orifice 8 (throttle member of the present invention) and the like.

As shown in FIG. 5, the nozzle body 2 is provided with an injection hole 9 for ejecting high-pressure fuel at its tip, and slidably holds the needle 3 on its inner peripheral portion. The nozzle body 2 has a suck hole 10 communicating with the injection hole 9,
A seat surface 11 connected to the suck hole 10, a fuel reservoir 12 communicating with the suck hole 10 at the time of fuel injection, and a fuel supply passage 13 for supplying high-pressure fuel to the fuel reservoir 12 are provided.

As shown in FIG. 5, the needle 3 has a seat portion 3a formed on the outer peripheral surface of the tip which has a conical shape.
The needle 3 descends and the seat portion 3a is seated on the seat surface 11 formed on the nozzle body 2 (state shown in FIG. 5).
As a result, the gap between the fuel reservoir 12 of the nozzle body 2 and the suck hole 10 is cut off, and the fuel injection is terminated. Further, when the needle 3 is lifted (moved upward in the drawing) and the seat portion 3a is separated from the seat surface 11, the suck hole 1
High-pressure fuel is supplied to 0, and fuel is injected from the injection hole 9.

The needle 3 is accommodated in the nozzle holder 5 and the back pressure acting on the rear end surface of the hydraulic piston 6 because the pressure of the high-pressure fuel flowing into the fuel reservoir 12 of the nozzle body 2 acts to lift the needle 3. The biasing force of the generated spring 14 acts in the direction of pushing down the needle 3. Then, when the back pressure of the hydraulic piston 6 rises above the valve closing pressure, the back pressure of the hydraulic piston 6 is pushed down, the seat portion 3a is seated on the seat surface 11, and when the back pressure of the hydraulic piston 6 falls below the valve opening pressure. Lift upward in the drawing to seat 3a
Moves away from the seat surface 11.

The tip packing 4 is sandwiched between the nozzle body 2 and the nozzle holder 5 to regulate the maximum lift amount of the needle 3. The tip packing 4 has a communication path 1 communicating with a fuel supply path 13 formed in the nozzle body 2.
5 is formed.

The nozzle holder 5 is formed with a long hole 16 penetrating its central portion in the longitudinal direction (vertical direction in FIG. 4).
The hydraulic piston 6 is slidably fitted into the elongated hole 16 and an intermediate member 17 is provided above the hydraulic piston 6.
(See FIG. 1) and a fixed orifice 8 (described later) are housed, and a pressure chamber 18 for introducing back pressure of the hydraulic piston 6 is formed between the hydraulic piston 6 and the fixed orifice 8. The upper end surface 5a of the nozzle holder 5 (three-way solenoid valve 7
The upper portion of the long hole 16 that is open to the mounting surface) is a storage portion 19 (recess of the present invention) that stores the intermediate member 17 and the fixed orifice 8, and the long hole 16 into which the hydraulic piston 6 is fitted and inserted. It has a larger diameter than the inner diameter of.

The nozzle holder 5 is provided with a fuel introduction passage 21 (high pressure introduction passage of the present invention) for introducing the high pressure fuel supplied from the introduction pipe through the pipe joint 20. The fuel introduction passage 21 is formed so as to extend in the longitudinal direction of the nozzle holder 5, one end of which is opened at the lower end surface on the side of the tip packing 4 and communicates with the communication passage 15 of the tip packing 4, and the other end is the three-way solenoid valve 7 The upper end surface 5a on the side is opened. The valve body of the present invention comprises the nozzle body 2 and the nozzle holder 5 described above.

The hydraulic piston 6 is connected to the needle 3 via a pressure pin 22 passing through the inside of the spring 14 arranged in the elongated hole 16 and is responsive to the back pressure of the hydraulic piston 6 (fuel pressure in the pressure chamber 18). The inside of the long hole 16 is displaced. The valve body of the present invention is composed of the needle 3 and the hydraulic piston 6 described above. The nozzle body 2, the tip packing 4, and the nozzle holder 5 described above are fastened by a retaining nut 23, as shown in FIGS. 4 and 5.

As shown in FIG. 4, the three-way solenoid valve 7 is installed on the upper part of the nozzle holder 5, and the retaining nut 2 is installed.
4 (the fastening means of the present invention), the body 25 is fastened to the nozzle holder 5, the coil 26 arranged above the body 25, the iron core 27, the armature 28, and the outer valve 29 and the inner valve 30 (both are incorporated therein). The passage switching valve of the present invention) and the like. In addition,
The coil 26, the iron core 27, the armature 28, the outer valve 29, the inner valve 30, and the like are retaining nuts 31 that cover the entire body together with the body 25 in a tubular shape.
Is assembled by.

In the body 25, the high pressure passage 3 communicating with the fuel introduction passage 21 of the nozzle holder 5 and filled with high pressure fuel.
2. Low-pressure passage 33 for discharging the overflowed fuel,
A communication passage 34 is formed so as to be able to communicate with either one of the high pressure passage 32 and the low pressure passage 33. In addition,
The high-pressure passage 32 opens at the lower end surface 25 a of the body 25 (a surface where the nozzle holder 5 is assembled) and is fluid-tightly connected to the fuel introduction passage 21 formed in the nozzle holder 5.

The coil 26 generates a magnetic force by being energized via a connector 35 provided at the upper end of the three-way solenoid valve 7. When the coil 26 is energized, the iron core 27 is magnetized and becomes an electromagnet. The armature 28 is arranged in the space formed by the spacer 36 between the body 25 and the iron core 27, and is attracted to the iron core 27 side serving as an electromagnet when the coil 26 is energized.

The outer valve 29 is slidably fitted in a fitting hole formed in the center of the body 25, and
The iron core 27 is connected to the armature 28 at its upper end.
Is urged downward in the drawing by a spring 37 arranged on the inner peripheral portion of the. Therefore, the outer valve 29 moves together with the armature 28 according to the energization state of the coil 26, and the position with respect to the body 25 changes.

Specifically, when the coil 26 is not energized, it is pushed downward in the drawing by the urging force of the spring 37, and the low-pressure passage 33 formed in the body 25.
When the coil 26 is energized by moving to an initial position (see FIG. 1) that shuts off between the communication path 34 and the communication path 34, the spring 3
A lift position in which the low pressure passage 33 and the communication passage 34 communicate with each other by being attracted to the iron core 27 side against the biasing force of the No. 7 (see FIG. 3).
Go to Further, the outer valve 29 has a coil 26
When the body 2 is not energized, that is, when it is pushed down to the initial position by the biasing force of the spring 37, the body 2
An oil passage 38 that connects the high-pressure passage 32 and the communication passage 34 formed in 5 is formed.

The inner valve 30 is disposed inside the outer valve 29, and the outer valve 29 serves as the inner valve 3.
It is configured to be slidable with respect to zero. The inner valve 30 shuts off the oil passage 38 formed in the outer valve 29 when the outer valve 29 is attracted to the iron core 27 side together with the armature 28 by energizing the coil 26.

The fixed orifice 8 is accommodated in the accommodating portion 19 formed in the nozzle holder 5 together with the intermediate member 17, and the bottom surface 19a of the accommodating portion 19 (see FIGS. 1 and 2) and the body 25 of the three-way solenoid valve 7 are accommodated. It is fixed tightly between the two. A fuel passage 39 is formed in the fixed orifice 8 to connect the communication passage 34 formed in the body 25 and the pressure chamber 18.

As shown in FIG. 1, the fuel passage 39 has a large diameter passage portion 39a communicating with the communication passage 34, a small diameter passage portion 39b communicating with the pressure chamber 18, and a large diameter passage portion 39a extending from the small diameter passage portion 39b. It consists of a funnel section 39c. The large diameter passage portion 39a is provided so that the passage inner diameter is approximately the same as the communication passage 34, and the small diameter passage portion 39b has a passage inner diameter smaller than that of the large diameter passage portion 39a, and forms the orifice of the present invention. The funnel portion 39c is provided in a funnel shape in which the passage cross-sectional area gradually decreases from the large diameter passage portion 39a toward the small diameter passage portion 39b.

The intermediate member 17 is made of, for example, an elastically deformable cold-rolled steel plate, is provided in a circular ring shape in which a round hole 17a having a diameter substantially the same as the inner diameter of the elongated hole 16 is formed in the central portion, and is accommodated in the storage portion. It is accommodated in 19 below the fixed orifice 8. That is, the intermediate member 17 is stored in the storage portion 19 before the fixed orifice 8. However, the total length of the fixed orifice 8 accommodated in the accommodating portion 19 is set to be shorter than the depth of the accommodating portion 19, but when the fixed orifice 8 is accommodated together with the intermediate member 17, as shown in FIG. Slightly protrudes from the upper end surface 5a of the nozzle holder 5. Specifically, for example, when the thickness t of the intermediate member 17 is 0.5 mm, the protrusion amount s is about 0.2 mm.

In this way, with the end face protruding, the storage section 1
Fixed orifice 8 and intermediate member 17 housed in 9
Is the body 25 of the three-way solenoid valve 7 with respect to the nozzle holder 5.
Is fastened by the retaining nut 24, the intermediate member 17 is crushed by receiving the tightening force of the retaining nut 24, and is compressed and deformed until the upper end surface 5a of the nozzle holder 5 and the lower end surface 25a of the body 25 come into close contact with each other. (Range of elastic deformation) and fixed.

Next, the operation of this embodiment will be described with reference to the time chart shown in FIG. The time chart of FIG. 6 shows a case where pilot injection is performed prior to main injection. FIG. 6A shows the behavior of the outer valve 29 of the three-way solenoid valve 7, and FIG. 6B shows the fixed orifice 8. Position (constant without changing in this embodiment), FIG.
6C shows the pressure fluctuation of the pressure chamber 18, and FIG. 6D shows the behavior of the needle 3.

First, when the coil 26 of the three-way solenoid valve 7 is not energized, the outer valve 29 is returned to the initial position, so that the pressure chamber 18 has the fuel passage 39 and the communication passage 3
4 and the high pressure passage 32 through the oil passage 38 (see FIG. 1). As a result, the pressure chamber 18 is filled with high-pressure fuel, and the internal pressure of the pressure chamber 18 is maintained at the valve closing pressure or higher. As a result, the needle 3 is pushed down via the hydraulic piston 6 and the pressure pin 22, and the seat portion 3a is seated on the seat surface 11, so that fuel is not injected.

After that, when the coil 26 of the three-way solenoid valve 7 is energized, the armature 28 is attracted to the iron core 27 against the biasing force of the spring 37, so that the outer valve 29 moves to the lift position together with the armature 28. To do. As a result, the inner valve 30 disposed inside the outer valve 29 has the oil passage 3 formed in the outer valve 29.
By disconnecting 8, the high pressure passage 32 and the communication passage 34 are disconnected, and at the same time, the low pressure passage 33 and the communication passage 34 are communicated (see FIG. 3).

As a result, the fuel filled in the pressure chamber 18 is discharged to the low pressure passage 33 through the fuel passage 39 and the communication passage 34 of the fixed orifice 8. As a result, as the fuel pressure in the pressure chamber 18 decreases, the needle 3 lifts together with the hydraulic piston 6 and the pressure pin 22, and the seat portion 3a of the needle 3 moves toward the seat surface 11a.
With the further separation, the high pressure fuel is supplied to the suck hole 10 and injected from the injection hole 9.

Here, when the fuel is discharged from the pressure chamber 18, since the orifice (small diameter passage portion 39b) is provided in the fuel passage 39 of the fixed orifice 8, the flow rate of the fuel flowing out from the pressure chamber 18 Can be suppressed. Therefore, the back pressure of the hydraulic piston 6 (fuel pressure in the pressure chamber 18)
Is gradually decreased, the lift operation of the needle 3 is also slowly performed, and the initial injection rate is decreased.

Subsequently, when the energization of the coil 26 of the three-way solenoid valve 7 is stopped, the outer valve 29 is returned to the initial position by the urging force of the spring 37, so that the oil passage 38
The high pressure passage 32 and the communication passage 34 are communicated with each other via the, and the high pressure fuel is filled in the pressure chamber 18 (see FIG. 1).

The fuel passage 39 of the fixed orifice 8 has a funnel portion 39c between the large diameter passage portion 39a and the small diameter passage portion 39b.
The funnel portion 39c is provided with a small diameter passage portion 39c in the flow direction when the fuel flows into the pressure chamber 18.
It has a funnel shape in which the passage cross-sectional area gradually decreases toward b. Therefore, the fuel passage 39 has a larger flow coefficient when the fuel flows into the pressure chamber 18 than when the fuel flows out of the pressure chamber 18, and thus the small-diameter passage when the fuel flows out of the pressure chamber 18. The flow rate of fuel passing through the small diameter passage portion 39b when the fuel flows into the pressure chamber 18 is larger than the flow rate of fuel passing through the portion 39b. As a result, the fuel pressure in the pressure chamber 18 rapidly rises to reach the valve closing pressure,
The needle 3 quickly descends to complete the fuel injection, and the disconnection becomes good.

Even in the pilot injection performed prior to the main injection, the initial injection rate can be reduced and a good injection can be obtained, as in the main injection. Further, in this embodiment, when the fuel is discharged from the pressure chamber 18, the small-diameter passage portion 39 of the fixed orifice 8 is surely used.
Since the fuel flows out after passing b, the initial injection rate of the main injection becomes low or high even if the injection interval between the pilot injection and the main injection is small.
So-called asymmetric injection does not occur.

(Effect of First Embodiment) In the fuel injection device 1 of this embodiment, the upper end surface 5a of the nozzle holder 5 and the three-way solenoid valve 7 are connected.
The intermediate member 17 is crushed and deformed until it comes into close contact with the lower end surface 25a of the body 25,
The fixed orifice 8 which receives the reaction force from can be closely fixed to the lower end surface 25a of the body 25. Thereby, the fuel introduction passage 21 formed in the nozzle holder 5,
Both can be liquid-tightly connected without causing fuel leakage with the high-pressure passage 32 formed in the body 25. As a result, it is not necessary to control the depth of the storage portion 19 and the total length of the fixed orifice 8 stored in the storage portion 19 with an accuracy of several microns, so that the number of processing steps can be significantly reduced and the cost can be reduced. be able to. The intermediate member 17 may be crushed not only in the elastic deformation range but also in the plastic deformation range.

(Second Embodiment) FIG. 7 is a cross-sectional view of an essential part showing the fixed orifice 8 assembled. In the first embodiment,
Although the intermediate member 17 is stored in the storage portion 19 before the fixed orifice 8, as shown in FIG.
The intermediate member 17 may be housed later.

(Third Embodiment) FIGS. 8 and 9 are cross-sectional views of a main portion showing a fixed orifice 8 assembled. In the first and second embodiments, the storage portion 19 is formed in the nozzle holder 5, but as shown in FIGS. 8 and 9, the storage portion 19 is formed in the body 25 of the three-way solenoid valve 7 and The fixed orifice 8 and the intermediate member 17 may be housed in the housing portion 19. At this time, as for the positional relationship between the fixed orifice 8 and the intermediate member 17, as shown in FIG. 8, the fixed orifice 8 may be stored in the storage portion 19 prior to the intermediate member 17.
As shown in FIG. 9, the intermediate member 17 may be stored in the storage portion 19 before the fixed orifice 8.

(Fourth Embodiment) FIGS. 10 and 11 are cross-sectional views of the essential parts showing the fixed orifice 8 assembled. In this embodiment, the fixed orifice 8 is directly fixed to the storage portion 19 without using the intermediate member 17. Specifically, as shown in FIGS. 10 and 11, screws 40 that are screwed into each other are formed on the inner peripheral surface of the storage portion 19 and the outer peripheral surface of the fixed orifice 8, and the storage portion is formed by screwing them together. The fixed orifice 8 can be fixed at 19. In this case, the storage portion 19 may be formed in the nozzle holder 5 as shown in FIG. 10, or may be formed in the body 25 of the three-way solenoid valve 7 as shown in FIG. However, in the case of the present embodiment, it goes without saying that the total length of the fixed orifice 8 accommodated in the accommodating portion 19 is set shorter than the depth of the accommodating portion 19. In addition to the screw connection described above, the fixed orifice 8 can be press-fitted and fixed into the storage portion 19.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part (at the time of fuel introduction) showing a fixed orifice assembled state.

FIG. 2 is a cross-sectional view showing an assembled state of a fixed orifice and an intermediate member before the three-way solenoid valve is assembled.

FIG. 3 is a cross-sectional view of a main part (at the time of fuel discharge) showing an assembled state of a fixed orifice.

FIG. 4 is an overall sectional view of a fuel injection device.

FIG. 5 is a sectional view of a nozzle portion.

FIG. 6 is a time chart showing the operation of the present embodiment.

FIG. 7 is a sectional view of a main part (second embodiment) showing an assembled state of a fixed orifice.

FIG. 8 is a cross-sectional view of a main part (third embodiment) showing an assembled state of a fixed orifice.

FIG. 9 is a cross-sectional view of a main part (third embodiment) showing an assembled state of a fixed orifice.

FIG. 10 is a cross-sectional view of a main part (fourth embodiment) showing an assembled state of a fixed orifice.

FIG. 11 is a cross-sectional view of a main part (fourth embodiment) showing an assembled state of a fixed orifice.

FIG. 12 is a cross-sectional view of essential parts for explaining the technique of the prior application.

[Explanation of symbols]

 1 Fuel Injection Device 2 Nozzle Body (Valve Main Body) 3 Needle (Valve Body) 5 Nozzle Holder (Valve Body) 5a Upper End Surface (Assembling Surface) of Nozzle Holder 6 Hydraulic Piston (Valve Body) 7 Three-way Solenoid Valve (Passage Switching Means) ) 8 fixed orifice (throttle member) 9 injection hole 17 intermediate member 18 pressure chamber 19 storage part (recess) 21 fuel introduction path (high pressure introduction path) 24 retaining nut (fastening means) 25a lower end surface of the body (assembly surface) ) 29 outer valve (passage switching valve) 30 inner valve (passage switching valve) 32 high pressure passage 33 low pressure passage 34 communication passage 39b small diameter passage portion (orifice)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F02M 61/16 F02M 61/16 P

Claims (6)

[Claims] 1. A valve main body having a high-pressure introduction passage for introducing high-pressure fuel, and a passage switching means formed with the valve main body in an axial direction to form a high-pressure passage connected to the high-pressure introduction passage. A throttle member housed in a recess opening in the valve body or an assembly surface of the passage switching means and having an orifice for connecting the valve body side and the passage switching means side; And fastening means for axially fastening the passage switching means and the throttle member together with the throttle member, the fastening means receiving the fastening force of the fastening means and the valve body and the assembling surface of the passage switching means. A fuel injection device, comprising: an intermediate member that compressively deforms until they come into close contact with each other. 2. The fuel injection device according to claim 1, wherein the throttle member is set so that the entire length of the throttle member accommodated in the recess is shorter than the depth of the recess. 3. A valve main body having a high-pressure introduction passage for introducing high-pressure fuel, and a passage switching means formed with the valve main body in an axial direction to form a high-pressure passage connected to the high-pressure introduction passage. A throttle member housed in a recess opening in the valve body or an assembly surface of the passage switching means and having an orifice for connecting the valve body side and the passage switching means side; And a fastening means for fastening the passage switching means in the axial direction, wherein the throttle member secures a predetermined clearance between the throttle body and the assembly surface of the passage switching means and the recess. Is fixed to the fuel injection device. 4. The fuel injection device according to claim 3, wherein the throttle member is screwed to an inner peripheral surface of the recess. 5. The fuel injection device according to claim 3, wherein the throttle member is press-fitted into the recess. 6. The fuel injection device according to any one of claims 1 to 5, wherein the passage switching means includes a communication passage communicating with the orifice.
And a low pressure passage leading to the low pressure side is provided,
A passage switching valve that switches between the high-pressure passage and the low-pressure passage and connects one of them to the communication passage is built in, and the valve body is provided with an injection hole that communicates with the high-pressure introduction passage. A valve body that opens and closes is slidably inserted, and a pressure chamber for introducing back pressure through the orifice is formed in the rear end surface of the valve body. When the back pressure introduced into this pressure chamber is equal to or lower than the valve opening pressure, A fuel injection device, wherein a valve body opens the injection hole, and the valve body closes the injection hole when a back pressure introduced into the pressure chamber is equal to or higher than a valve closing pressure.