JPH08246991A - Fuel injection device - Google Patents

Abstract

PURPOSE: To improve durability and reliability and to improve assembling ability by preventing breakage of an insulation cover. CONSTITUTION: A fuel injection device comprises a fuel injection valve to inject fuel directly to the combustion chamber of an internal combustion engine; and an ignition plug formed integrally with the injection valve. A cap sub-assembly 23 having an insulation cover 13 located between a valve seat 5, in which the valve 10 of a fuel injection valve is incorporated and which is the central electrode of an ignition plug, and a cap 11 having the earth electrode 12 of the ignition plug is assembled in a housing 20 in such a state that an regulating plate 22A to effect fine-regulation of the opening closing stroke of the valve 10 through adjustment of a plate thickness (t) is located. A contact member 18A made of a metal making contact with the regulating plate 22A is arranged at the cap sub-assembly 23 to prevent contact between an insulation cover 13 and a regulation plate 22A.

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 mainly used in a vehicle internal combustion engine (also called an engine).

[0002]

2. Description of the Related Art A conventional fuel injection device is shown in FIG.
As shown in a sectional view in FIG. 1, there is a fuel injection valve that directly injects fuel into a combustion chamber of an engine, and an ignition plug that is integrally formed with the fuel injection valve. Note that hatching showing a cross section is omitted in FIG. In the fuel injection valve, the high-pressure fuel supplied from a fuel tank (not shown) under a predetermined pressure is a housing sub-assembly (corresponding to the housing in the present invention) 20.
From the fuel inlet 1 to the inside of the valve seat 5 through the fuel passage in the housing sub-assembly 20. However, when the valve 10 closes the injection port 5a of the valve seat 5 due to the elasticity of the valve spring 9, fuel is not injected. Here, when the coil 42 is energized, the valve 10 is opened by the suction force of the core 2 acting on the armature 3 to inject fuel.

In the ignition plug, the high voltage from the ignition coil causes the high tension cord 6, the screw stopper 7, the set screw 8, the valve spring 9,
The electric field is transmitted to the valve seat 5 via the valve 10, and spark discharge is generated between the edge portion 5b and the ground electrode (also referred to as a GND electrode) 12 facing the edge portion 5b with the valve seat 5 as a central electrode. An example of this type of fuel injection device is disclosed in Japanese Utility Model Laid-Open No. 63-154760.

In the above fuel injection device, the ground electrode 12
The valve seat 5 is inserted in the cap 11 having the above, and a ceramic insulating cover 13 for electrical insulation is interposed between the valve seat 5 and the cap 11. The configuration of the peripheral portion of the cap 11 is shown enlarged in FIG. The valve seat 5, the cap 11, and the insulating cover 13 are assembled to form a cap sub-assembly 23, and the cap sub-assembly 23 is assembled by inserting the cap sub-assembly 23 in the housing sub-assembly 20 in its axial direction.

When the cap sub-assembly 23 is assembled, a ring-shaped metal adjustment plate 22 is interposed between the mutual members. The adjustment plate 22 is interposed between the insulating cover 13 and the yoke 17 that houses the core 2, the coil 42, and the like, and is assembled to the housing sub-assembly 20. The opening / closing stroke of the valve 10 is finely adjusted by adjusting the plate thickness T of the adjusting plate 22.

[0006]

According to the fuel injection device, the adjustment work of the opening / closing stroke of the valve 10 is performed by adjusting the plate thickness T of the adjusting plate 22 so that the opening / closing stroke becomes an appropriate amount, for example, by polishing to reduce the thickness. For this purpose, the cap sub-assembly 23 is repeatedly taken out from the housing sub-assembly 20 and re-inserted each time the polishing is performed. At this time, the insulating cover 13 is abutted against the adjustment plate 22 every time the cap sub-assembly 23 is inserted into the housing sub-assembly 20.

Then, since the insulating cover 13 is made of ceramic, which is more brittle than metal, damages such as scratches and cracks are likely to occur at its abutting portion, which makes the opening / closing stroke of the valve 10 unstable and lowers the injection performance. , And durability and reliability may be reduced. Furthermore, in order to prevent such a problem, the adjustment work must be carefully performed, which requires a long working time, resulting in poor assembly.

The technical problem to be solved by the present invention is
It is an object of the present invention to provide a fuel injection device capable of improving durability and reliability and improving assembling property by preventing damage to the insulating cover.

[0009]

According to the invention of claim 1, which solves the above-mentioned problems, a fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine, and an ignition plug formed integrally with the fuel injection valve are provided. A valve seat of the fuel injection valve, which is installed so as to move forward and backward and serves as a center electrode of the spark plug; a cap having the valve seat inserted therein and having a ground electrode of the spark plug; An insulating cover for electrical insulation interposed between the seat and the cap is assembled to form a cap sub-assembly, and when the cap sub-assembly is incorporated in the housing in the axial direction thereof, a metal adjustment plate is provided between mutual members. In the fuel injection device in which the valve opening / closing stroke is finely adjusted by adjusting the plate thickness of the adjusting plate, A fuel injection device provided with the adjusting plate and abutting the metal contact member.

[0010]

According to the fuel injection device of the first aspect, when the cap sub-assembly is inserted into the housing in the work of adjusting the opening / closing stroke of the valve, the metal contact member provided on the cap sub-assembly contacts the adjustment plate. Therefore, the insulating cover is not burdened by the contact with the adjusting plate, and is not damaged or broken.

[0011]

EXAMPLES Examples will be described with reference to the drawings. Since this example is a modification of a part of the above-mentioned conventional example, the same or equivalent parts are designated by the same reference numerals. In FIG. 1 showing a cross-sectional view of the fuel injection device,
The fuel injection device is roughly composed of a housing sub-assembly 20 having a substantially hollow cylindrical shape, a body sub-assembly 21, a valve sub-assembly 4 and a cap sub-assembly 23 which are assembled to the housing sub-assembly 20. . In FIG. 1, hatching showing a cross section is omitted.

As shown in the sectional view of FIG. 3, the housing sub-assembly 20 is composed of an inner cylindrical body 34 and an outer cylindrical body 35 which are substantially hollow cylindrical and which are double-inserted inside and outside. For more information,
The inner cylindrical body 34 made of SUS304 material is inserted into the outer cylindrical body 35 made of SUS magnetic material, and is attached to substantially the upper half of the outer cylindrical body 35. An appropriate number of grooves 34a are provided on the outer peripheral surface of the lower half of the inner cylindrical body 34 along the axial direction. In addition, an appropriate number of groove lines 3 are provided on the outer peripheral surface of the upper end portion of the outer cylindrical body 35.
5a is provided along the axial direction. These groove 3
4a and 35a form a fuel passage communicating with each other in the axial direction by insertion of the tubular bodies and having both axial ends (upper and lower ends in the drawing) open. Further, the outer tubular body 35 is provided with a flange member 60 fixed to its upper end portion so as to form a stepped and expanded shape.

The inner cylindrical body 34 is formed by the flange member 60.
As shown in FIG. 1, the annular space formed around the
A ring-shaped joint component 37 is rotatably fitted in a state in which a gap is maintained between the lower surface and the bottom surface of the annular space portion. The joint part 37 has the SUS30 attached to the inner cylindrical body 34.
It is fixed by tightening a fixing nut 38 made of three materials. The joint component 37 is formed with a fuel intake port 1 having one end opening to the end face of the connecting portion 36 protruding to the outer side surface and the other end opening to the lower face. While the strainer 39 is incorporated in the connection part 36,
A fuel supply pipe is connected to. The joint component 37 is provided with O-rings 30 and 31 for keeping airtightness between the joint members 37 and the cylinders 35 and 34, respectively.

The body sub-assembly 21 incorporated in the housing sub-assembly 20 is composed of a ring-shaped SUS304 material, as shown in the sectional view of FIG.
A block 15, a spring guide 41 made of a substantially hollow cylindrical electrical insulating material such as polyphenylene sulfide resin (also referred to as PPS resin) in which the second block 15 is insert-molded on the outer periphery of the central portion, and fitted to the spring guide 41. Further, a core 2 made of a substantially hollow cylindrical magnetic material, a bobbin 16 made of an electric insulating material such as PPS resin fitted on the outer peripheral surface of the core 2, and the bobbin 1
6 is provided with a coil 42 wound in multiple layers, and a first block 14 made of a ring-shaped SUS304 material fitted on the outer peripheral surface of the lower end portion of the core 2, and is formed into a substantially hollow cylindrical shape. It is fitted inside a yoke 17 made of an SUS type magnetic material. The spring guide 41 has a core 2
An O-ring 27 for maintaining airtightness between the first block 14 and the yoke 17 and the core 2 is provided for the first block 14 respectively.

The connecting end of the coil 42 is drawn out into an annular space 16a formed at the upper end of the bobbin 16. On the other hand, the coil connection side end of the harness 43 is drawn into the space 16a through the upper flange portion of the core 2 from between the second block 15 and the spring guide 41, and the coil 42 is connected in the space 16a. Electrically connected to the end. A proper number of grooves 17a are provided on the outer peripheral surface of the yoke 17 along the axial direction. The groove 17a opens on the upper end surface of the yoke 17, and the lower end thereof is connected to a communication hole 44 penetrating in the yoke radial direction at the lower end of the yoke 17.

The body sub-assembly 21 is inserted in the lower half of the housing sub-assembly 20 as shown in FIG. With this attachment, the harness 43 is pulled out upward through the inside of the housing sub-assembly 20. The lead-out end of the harness 43 is electrically connected to an electronic control unit (also referred to as an ECU) not shown, and the coil 42 receives an input from the electronic control unit to energize or deenergize the coil.

The groove 17a of the yoke 17 forms a fuel passage communicating in the axial direction by being inserted into the outer cylinder 35. This fuel passage communicates with the fuel passage formed by the grooves 34a, 35a in the housing sub-assembly 20 through a space surrounded by the inner cylinder 34, the outer cylinder 35, the yoke 17 and the second block 15. The upper end of the second block 15 is fitted in the inner cylindrical body 34. The second block 15 is provided with an O-ring 28 that maintains airtightness with the inner cylindrical body 34.

At the upper end of the spring guide 41,
A set screw 8 and a set screw stopper (called a screw stopper) 7 made of SUS303 material are sequentially screwed. Specifically, the set screw 8 has a groove 8a.
The head itself having is screwed to the spring guide 41. A pipe 61 made of SUS303 material that comes into contact with a valve spring 9 described later is rotatably fitted into the shaft end of the set screw 8. Pipe 61
Rotates relative to the set screw 8 when the set screw 8 is screwed in, and prevents twisting due to rotation of the valve spring 9. The set screw 8 is provided with an O-ring 29 that keeps airtightness with the spring guide 41.

The lower end of the screw stopper 7 is screwed onto the spring guide 41. The connection terminal 6a of the high tension cord 6 is electrically connected to the rectangular groove-shaped socket portion 7a formed on the upper end portion of the screw stopper 7. A filling material 46 such as epoxy resin for sealing the space around the high tension cord 6 and the harness 43 is loaded on the upper end of the inner cylindrical body 34.

The valve sub-assembly 4 incorporated in the lower end of the body sub-assembly 21 is a shaft-shaped valve 10 made of SUS440C material, as shown in the sectional view of FIG.
And a valve support 48 made of an electrical insulating material, for example, PPS resin, in which the upper end of the valve 10 is insert-molded,
An armature 3 made of a magnetic material and insert-molded on the outer periphery of the central portion of the valve support 48. The valve support 48 has an appropriate number (for example, 4
A fuel escape passage 49 composed of a through hole is formed. The upper half of the valve support 48 is formed in a hollow cylindrical shape. Further, the valve 10 has a fuel guide portion 51 which is formed in a substantially columnar shape at the tip of the shaft portion 50 and has a swirl forming screw groove on the outer peripheral surface thereof, and a substantially conical shape provided at the tip of the fuel guide portion 51. Valve part 52
And a slide portion 53 formed in a flange shape at the center of the shaft portion 50.

The valve sub-assembly 4 is fitted in a body sub-assembly 21 so as to be vertically movable, as shown in FIG. For details, see SUS3 inside the spring guide 41.
After inserting the valve spring 9 made of 04 material, the valve support 48 is fitted in the spring guide 41 with the lower end of the valve spring 9 fitted with the tubular portion of the valve support 48. And Armature 3
It is located in the lower end portion of the yoke 17 and its upper end surface faces the lower end surface of the core 2 and receives a suction force from the core 2 when the coil 42 is energized. Also, the yoke 1
The open end of the communication hole 44 of 7 communicates with the space portion around the valve support 48. The structure around the valve sub-assembly 4 is well shown in the enlarged view of FIG.

As shown in the sectional view of FIG. 6, the cap sub-assembly 23 incorporated in the lower end portion of the housing sub-assembly 20 has a substantially hollow cylindrical shape and is made of a stainless alloy material having a nozzle 5a at its lower end ( For example NC
A valve seat 5 made of F713 or 718 material) and having a substantially hollow cylindrical shape and having the valve seat 5 therein.
And a ceramic insulating cover 13 into which the valve seat 5 is screwed, and a SUS in which the insulating cover 13 has a substantially hollow cylindrical shape and is inserted therein.
And a cap 11 made of a system material. The insulating cover 13 is interposed between the valve seat 5 and the cap 11 for electrical insulation between the two members.

The lower end of the cap 11 is made of a Ni alloy material and has a lower end edge 5b of the valve seat 5.
The ground electrode 12 is provided to point to. On the outer peripheral surface of the cap 11, a male screw 11a for screwing on a cylinder head (not shown) of the internal combustion engine is formed. The valve seat 5 is provided with an O-ring 19 for maintaining airtightness between the valve seat 5 and the insulating cover 13.
The O-ring 24 that keeps airtightness with the cap 11
Is provided. The upper edge of the cap 11 is crimped to the insulating cover 13 via an O-ring 32. Gaskets 54 and 55 made of copper or iron are interposed between the valve seat 5 and the insulating cover 13 and between the insulating cover 13 and the cap 11.

The cap sub-assembly 23 is incorporated in the housing sub-assembly 20 as shown in FIG. 2. Specifically, the valve seat 5 is provided in the valve seat 5.
Is slidably inserted, and the cap 11 is fitted to the lower end of the outer cylindrical body 35 and fixed by laser welding. The valve sub-assembly 4 is normally urged downward in the figure by the elasticity of the valve spring 9, and the valve element 52 of the valve 10 is held in a state in which the injection port 5a of the valve seat 5 is closed. The slide portion 53 of the valve 10 has a substantially circular shape that is slidably fitted in the valve seat 5, and a peripheral portion of the slide portion 53 is partially cut to form a fuel passage portion that opens in the axial direction. .

However, before the assembling, the cap 1
1 is made of a metal, such as S, which faces the yoke 17 in advance.
A cylindrical ring cylinder 18A made of US303 material is inserted by press fitting. The ring cylinder 18A is
It corresponds to the contact member in the present invention. A ring-shaped adjustment plate 22A made of metal, for example, SUS440C-based material is interposed between the ring cylinder 18A and the yoke 17 facing the ring cylinder 18A. Note that the adjustment plate 22A and the tip of the ring 18A (the upper end in the figure)
Is fitted to the end of the yoke 17. Further, the insulating cover 13 is not in contact with the yoke 17, and the inner diameter of the upper end portion of the insulating cover 13 is formed larger than the large diameter portion of the valve support 48, so that the insulating cover 13 and the valve support 48 are separated from each other. A fuel passage communicating between the communication hole 44 of the yoke 17 and the valve seat 5 is formed therebetween.

The O-rings 19 and 2 used for the above-mentioned respective parts
Nos. 4 to 32 are all made of a fluororubber material. Further, the material specified for each member is not limited to that, and may be any material satisfying the condition required for each member.

First, the operation of the fuel injection valve in the fuel injection device will be described. The fuel supplied under a predetermined pressure from a fuel tank (not shown) is filtered by the strainer 39 of the fuel inlet 1 and then reaches the inside of the valve seat 5 through the fuel passage. However,
Since the valve 10 is held by the elasticity of the valve spring 9 so that the injection port 5a of the valve seat 5 is closed, fuel injection from this injection port 5a does not occur.

When the coil 42 is energized by the input of an electric signal from the electronic control unit, the valve sub-assembly 4 is retracted by the attraction force of the core 2 acting on the armature 3. As a result, the injection port 5a of the valve seat 5 is opened, and fuel is injected from here. At this time, the fuel is
A swirl is formed by the screw groove of the fuel guide portion 51 of the valve 10 while being given a swirling motion to form a swirl, and the swirl is injected from the injection port 5a with a wide spray angle. Then, when the electric signal to the coil 42 is turned off and the attraction force of the core 2 acting on the armature 3 is released, the elasticity of the valve spring 9 advances the valve sub-assembly 4, and the valve 10 re-opens the injection port 5a. Since it is maintained in the closed state, the fuel injection from this injection port 5a is stopped.

Next, the operation of the spark plug will be described.
The high voltage from the ignition coil is high tension cord 6, screw stopper 7, set screw 8, pipe 6
1, the air is transmitted to the valve seat 5 via the valve spring 9 and the valve 10, and spark discharge is generated between the edge portion 5b of the valve seat 5 as a center electrode and the ground electrode 12 facing the edge seat 5b, thereby producing a mixture in the combustion chamber. Ignite.

Next, the procedure for assembling each sub-assembly of the fuel injection device will be listed. (1) Insert the body sub-assembly 21 into the housing sub-assembly 20. The set screw 8 is screwed onto the spring guide 41 of the body sub-assembly 21 before the assembling. (2) The valve spring 9 is attached to the spring guide 41.
Insert the valve sub-assembly 4 into the body sub-assembly 21 and the adjustment plate 2 into the yoke 17.
Set 2A. (3) The cap sub-assembly 23 to which the ring cylinder 18A is attached by press fitting is inserted into the housing sub-assembly 20. At this time, the plate thickness t of the adjustment plate 22A is adjusted so that the opening / closing stroke of the valve 10 becomes appropriate. The adjustment work will be described in detail later. (4) After that, the outer cylindrical body 35 of the housing sub-assembly 20 and the cap 11 of the cap sub-assembly 23 are fixed by laser welding. The harness 43 is pulled out upward through the inside of the housing sub-assembly 20. (5) After finely adjusting the spring force of the valve spring 9 to the valve 10 by rotating the set screw 8, the screw stopper 7 is screwed to the spring guide 41 to fix the set screw 8. (6) The high tension cord 6 is connected to the screw stopper 7, and the high tension cord 6 and the harness 43 are connected.
The filling material 46 is loaded in the surrounding space and the assembly is completed.

An example of the work for adjusting the plate thickness t of the adjusting plate 22A performed in the third item of the assembling procedure will be described with reference to the explanatory view of FIG. FIG. 7 is a partially cutaway front view of the state immediately before the adjustment plate 22A and the cap sub-assembly 23 are inserted into the housing sub-assembly 20. Set the adjustment plate 22A on the housing sub-assembly and then the ring cylinder 1
Insert the cap sub-assembly 23 with 8A attached. The opening / closing stroke of the valve 10 is measured in this temporarily assembled state. At the time of this measurement, when a linear gauge is used, for example, the detector of the linear gauge is inserted from the injection port of the valve seat 5 and the fuel injection valve is actually operated to measure the opening / closing stroke of the valve 10. After that, the cap sub-assembly 23 and the adjusting plate 22A are once taken out from the housing sub-assembly 20, and the plate 22 is polished to reduce the plate thickness t thereof. By repeating the above work, the opening / closing stroke of the valve 10 is finely adjusted to an appropriate amount.

According to the fuel injection device, the cap sub-assembly 23 is repeatedly inserted into and removed from the housing sub-assembly 20 until the opening / closing stroke of the valve 10 reaches an appropriate amount.
Each time the is inserted into the cap sub-assembly 23, the metal ring cylinder 18A hits the adjustment plate 22A, and the conventional ceramic insulating cover 13 does not hit any member. Therefore, it is possible to prevent the insulating cover 13 from being damaged, such as being damaged or cracked, due to the contact of the insulating cover 13 with the adjustment plate 22A. As a result, the opening / closing stroke of the valve 10 is stable and the injection performance is improved, so that durability and reliability are improved, while the carefulness of the adjustment work can be reduced and the work time can be shortened, so that the assemblability is improved.

[0033]

According to the fuel injection device of the first aspect of the present invention, it is possible to prevent damage due to abutting of the insulating cover with the adjusting plate in the work of adjusting the opening / closing stroke of the valve, thereby improving the durability and reliability. The attachability can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a fuel injection device.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a sectional view showing a housing sub-assembly.

FIG. 4 is a sectional view showing a body sub-assembly.

FIG. 5 is a sectional view showing a valve sub-assembly.

FIG. 6 is a sectional view showing a cap sub-assembly.

FIG. 7 is an explanatory diagram showing a work of adjusting an opening / closing stroke of a valve.

FIG. 8 is a sectional view of a conventional fuel injection device.

9 is an enlarged view of a main part of FIG.

[Explanation of symbols] 5 valve seat 10 valve 11 cap 12 ground electrode 13 insulating cover 18A ring cylinder (contact member) 20 housing sub-assembly (housing) 22A adjustment plate 23 cap sub-assembly

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F02P 13/00 303 F02M 51/02 F

Claims (1)

[Claims] 1. A fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine, and an ignition plug integrally formed with the fuel injection valve, wherein the valve of the fuel injection valve is incorporated so as to be movable back and forth. And a valve seat serving as a center electrode of the spark plug, a cap having the valve seat inserted therein and having a ground electrode of the spark plug, and an insulating cover for electrical insulation interposed between the valve seat and the cap. To form a cap sub-assembly, and when the cap sub-assembly is assembled in the housing in its axial direction, a metal adjusting plate is interposed between the mutual members, and the valve thickness is adjusted to open / close the valve. In the fuel injection device that finely adjusts the stroke, a metal contact member that contacts the adjustment plate is provided on the cap sub-assembly. A fuel injection device characterized by being struck.