JPH08232808A - Fuel injection device - Google Patents

Abstract

PURPOSE: To form the fuel guide of a valve with good size accuracy and in a low cost, and improve fuel injection performance in a low cost. CONSTITUTION: This device is provided with a fuel injection valve provided with a valve seat 5 which is formed in nearly hollow cylindrical shape and having an injection port 5a on a top end part, and a valve 10 which is opening/ closing-movably formed in an axial direction in the valve seat 5. A fuel guide part 51 having a screw groove 51a for forming swirl on the outer circumferential surface thereof is formed on the valve 10. The fuel guide part 51 is formed integratedly with the valve 10 by resin forming. The fuel guide part 51 having good size accuracy in comparison with when the screw groove 51a is cutting worked on the valve-self is thus formed in a low cost and easily.

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.

[0002]

2. Description of the Related Art In a conventional fuel injection device, for example, as shown in a sectional view of FIG. 4, a valve seat 105 having a substantially hollow cylindrical shape and having an injection port 105a at its tip is provided in the valve seat 105. There is a fuel injection valve that includes a valve 110 that is openable and closable in the axial direction, and the valve 110 is also provided with a fuel guide portion 151 that has a swirl forming screw groove 151a on the outer peripheral surface.

According to the fuel injection device, the valve 110
With the opening of the valve, the fuel flows along the screw groove 151a of the fuel guide portion 151 to give a swirling motion to the fuel, and a wide spray angle is formed by being injected as swirl from the injection port 105a. In this way, it is known to improve fuel combustion by injecting fuel at a wide spray angle. An example of this type of fuel injection device is disclosed in JP-A-56-2457.

[0004]

The groove cross-sectional area and screw shape of the screw groove 151a in the fuel injection device are as follows.
Since the fuel injection performance is greatly affected, its dimensional accuracy is very important. By the way, the valve 11 in the conventional example
0 is a metallic material such as stainless steel (for example, SUS440
C), and the screw groove 151a is formed by subjecting itself to cutting.
However, the fuel guide portion 1 in which the screw groove 151a is engraved
51 is a material that belongs to the harder of metals, and the outer diameter of the fuel guide portion 151 is, for example, φ4.0 to 4.5.
Since the screw groove 151a is small and the groove cross-sectional area of the screw groove 151a is small, it is difficult to process the screw groove 151a, the processing cost is high, and it is difficult to obtain a desired dimensional accuracy. There are also many.
As a countermeasure, it is easy to adopt a metal material having excellent workability for the valve 110. However, this makes it difficult to secure the durability of the valve member 152 to which the impact due to the opening / closing motion is applied, which is a preferable means. I can't say.

The technical problem to be solved by the present invention is as follows.
It is an object of the present invention to provide a fuel injection device capable of forming a fuel guide portion of a valve with high dimensional accuracy and at low cost and improving fuel injection performance at low cost.

[0006]

In order to solve the above-mentioned problems, the present invention according to claim 1 provides a valve seat which has a substantially hollow cylindrical shape and has an injection port at its tip, and an opening / closing motion in the valve seat in the axial direction. Having a fuel injection valve with a valve provided,
In the fuel injection device, wherein the valve is provided with a fuel guide portion having a swirl forming screw groove on an outer peripheral surface thereof, the fuel guide portion is integrally formed with the valve by resin molding. According to a second aspect of the present invention, the fuel injection valve is a fuel injection valve that directly injects fuel into a combustion chamber of an internal combustion engine, and the fuel injection valve is integrally formed with an ignition plug. It is an injection device.

[0007]

According to the fuel injection device of the first aspect, the fuel guide portion having the screw groove is integrally formed with the valve by resin molding, so that the dimensional accuracy is higher than that in the case where the screw groove is cut on the valve itself. The fuel guide portion can be easily formed at low cost. Since the valve itself does not need to be processed with a screw groove, the durability of the valve can be ensured by adopting a hard material for the valve. According to the fuel injection device of claim 2, even in the case where the fuel injection valve integrally configured with the spark plug cannot have a large valve outer diameter due to its design, the size of the fuel guide portion is small but the dimension accuracy is low. It can be easily formed at a cost.

[0008]

EXAMPLES Examples will be described with reference to the drawings. Since the present embodiment is implemented in a fuel injection device including a fuel injection valve that directly injects fuel into a combustion chamber of an internal combustion engine, and an ignition plug integrally configured with the fuel injection valve, The outline of the fuel injection device will be described, and then the main parts will be described. In FIG. 2, which shows a cross-sectional view of the fuel injection device, the fuel injection device is roughly divided into a housing sub-assembly 20 having a substantially hollow cylindrical shape, a body sub-assembly 21 mounted on the housing sub-assembly 20, and a valve sub-assembly. It is composed of an assembly 4 and a cap sub-assembly 23. Note that hatching showing a cross section is omitted in FIG.

The housing sub-assembly 20 has a substantially hollow cylindrical shape, and the inner cylindrical body 34 and the outer cylindrical body 3 are inserted in the inner and outer double layers.
It consists of 5. Specifically, 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 almost the upper half portion of the outer cylindrical body 35.
On the outer peripheral surface of the lower half portion of the inner cylindrical body 34, a suitable number of grooves 34a are provided along the axial direction. Further, an appropriate number of grooves 35a are provided on the outer peripheral surface of the upper end portion of the outer tubular body 35 along the axial direction. These groove lines 34a, 35a form a fuel passage that is axially communicated with each other by being inserted into each other and is open at both axial ends (upper and lower ends in the drawing). Further, the outer cylindrical body 35 is provided with a flange member 60 having a stepped and expanded shape at the upper end thereof.

By the flange member 60, the inner cylindrical body 34
A ring-shaped joint part 37 made of SUS material is rotatably fitted in the annular space portion formed around it with a gap formed between the lower surface and the bottom surface of the annular space portion. There is. The joint part 37 is fixed by fastening a fixing nut 38 made of SUS303 material to the inner cylinder 34. The joint component 37 is formed with a fuel intake port 1 having one end opening to the outer side surface and the other end opening to the lower surface. A strainer 39 is incorporated in an inlet portion at one end of the fuel intake port 1, and a fuel supply pipe is connected to the strainer 39. The joint component 37 is provided with O-rings 30 and 31 for maintaining airtightness with the respective cylinders.

A body sub-assembly 21 is incorporated in the housing sub-assembly 20. The body sub-assembly 21 includes a second block 15 made of a ring-shaped SUS304 material, and a substantially hollow cylindrical electrical insulating material formed by insert molding the second block 15 on the outer periphery of the central portion, such as polyphenylene sulfide resin (also PPS resin). , A core 2 made of a substantially hollow cylindrical magnetic material fitted to the spring guide 41, and a bobbin made of an electrically insulating material such as PPS resin fitted to the outer peripheral surface of the core 2. 16, a coil 42 wound around the bobbin 16 in multiple layers, and a ring-shaped SUS304 fitted on the outer peripheral surface of the lower end portion of the core 2.
A first block 14 made of a material, and they are fitted from above into a yoke 17 made of a SUS magnetic material having a substantially hollow cylindrical shape. The spring guide 41 has an O-ring 27 that maintains airtightness with the core 2.
Further, the first block 14 is provided with O-rings 25 and 26 for maintaining airtightness between the yoke 17 and the core 2.

An appropriate number of grooves 17a are provided on the outer peripheral surface of the yoke 17 along the axial direction. This groove 17
The opening a is formed in 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 near the lower end of the yoke 17. The connecting end of the coil 42 is an annular space 1 formed at the upper end of the bobbin 16.
6a. On the other hand, the coil side connection end of the harness 43 is connected to the second block 15 and the spring guide 41.
And the space portion 1 through the flange portion of the core 2 after being drawn into the concave portion 15a of the second block 15 through
6a and is electrically connected to the connection end of the coil 42 in the space 16a.

The body sub-assembly 21 is inserted in the lower half of the housing sub-assembly 20. With this insertion, the harness 43 is pulled out upward through the inner cylindrical body 34 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 with the axial direction by inserting 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.

On the upper end of the spring guide 41, a set screw 8 made of SUS303 material and a set screw stopper (referred to as screw stopper) 7 are sequentially screwed. Specifically, the head itself of the set screw 8 having the groove 8a 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. The pipe 61 rotates relative to the screw 8 when the set screw 8 is screwed in, and prevents the twisting due to the rotation of the valve spring 9. Further, the set screw 8 is provided with an O-ring 29 that maintains airtightness with the spring guide 41. Screw stop 7
The lower end of the is screwed to 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. Incidentally, the inner cylindrical body 34
High tension cord 6 and harness 4 at the upper end of
3 Filling material 4 such as epoxy resin for sealing the space around it 4
6 is loaded.

A valve sub-assembly 4 is incorporated at the lower end of the body sub-assembly 21. The structure around the valve sub-assembly 4 is shown in detail in the sectional view of FIG. In FIG. 3, the valve sub-assembly 4 is S
A shaft-shaped valve 10 made of US440C material and an electric insulating material, for example, P, formed by insert molding the upper end portion of the valve 10.
The valve support 48 is made of PS resin, and the armature 3 made of a magnetic material is insert-molded on the outer periphery of the center of the valve support 48. On the outer peripheral portion of the valve support 48, a fuel escape passage 49 is formed which is composed of an appropriate number of (for example, four) through holes penetrating in the axial direction. The upper half of the valve support 48 has a hollow cylindrical shape (see FIG. 2). Further, the valve 10 is provided with a fuel guide portion 51 which is formed in a substantially columnar shape at a tip portion of the shaft portion 50 and has a swirl forming screw groove 51 a on an outer peripheral surface thereof, and a fuel guide portion 51 provided at a tip portion of the fuel guide portion 51. It has a conical valve part 52 and a pair of upper and lower slide parts 53 formed in the shaft part 50 in a flange shape.

As shown in FIG. 2, the valve sub-assembly 4 is fitted in the body sub-assembly 21 so as to be vertically movable. 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. . The armature 3 is
It is located inside the lower end 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. The opening end of the communication hole 44 of the yoke 17 communicates with the space around the valve support 48.

A cap sub-assembly 23 is incorporated at the lower end of the housing sub-assembly 20. The cap sub-assembly 23 has a substantially hollow cylindrical shape and a valve seat 5 made of a stainless alloy material (for example, NCF 713 or 718 material) having a nozzle 5a at its lower end, and a substantially hollow cylindrical shape, and the valve seat 5 is formed inside the valve seat 5. It is composed of a ceramic cover 13 to which the sheet 5 is screwed, and a cap 11 made of a SUS material having a substantially hollow cylindrical shape and having the cover 13 inserted therein.

The lower end of the cap 11 is provided with a GND electrode 12 made of a Ni alloy material and having its front end directed toward the lower end edge 5b of the valve seat 5. On the outer peripheral surface of the cap 11, a male screw 11a for screwing on the cylinder head of the internal combustion engine is formed. The valve seat 5 is provided with an O-ring 19 for maintaining airtightness with the cover 13, and the cover 13 is provided with an O-ring 24 for maintaining airtightness with the cap 11. The upper edge of the cap 11 is the cover 1
It is crimped to the No. 3 through the O-ring 32. Further, between the valve seat 5 and the cover 13, and the cover 13
Gaskets 54 and 55 made of copper are interposed between the cap 11 and the cap 11.

The cap sub-assembly 23 is incorporated in the housing sub-assembly 20 as described below. That is, the valve 10 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. Also, the slide portion 5 of the valve 10
3 has a substantially circular shape that is slidably fitted in the valve seat 5 and forms a fuel passage portion that opens in the axial direction by partially cutting the outer peripheral portion. The valve 10 is opened and closed by sliding the slide portion 53 with respect to the valve seat 5, and there is a slight gap between the outer peripheral surface of the fuel guide portion 51 and the inner peripheral surface of the valve seat 5.

A stroke adjusting ring 18A made of a cylindrical SUS303 material is attached to the end of the cap 11 facing the yoke 17. A ring-shaped stroke adjusting plate 22A made of a SUS440C-based material is interposed between the stroke adjusting ring 18A and a portion of the yoke 17 facing the stroke adjusting ring 18A.
By adjusting the plate thickness of the plate 22A, the opening / closing stroke of the valve sub-assembly 4 is set to an appropriate amount. Further, the stroke adjusting plate 22A and the ring 1
The front end portion (upper end portion in the drawing) of 8A is fitted to the end portion of the yoke 17 facing the cap 17. The cover 13 is not in contact with the yoke 17, and the inner diameter of the upper end portion of the cover 13 is formed larger than the large diameter portion of the valve support 48, and the yoke is provided between the cover 13 and the valve support 48. A fuel passage is formed from the communication hole 44 of 17 to the inside of the valve seat 5.

The O-rings 19 and 2 used for the above 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 device, 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 51a of the fuel guide portion 51 of the valve 10 flowing while being given a swirling motion, and the swirl is injected from the injection port 5a with a wide spray angle. Then, the electric signal to the coil 42 is turned off,
When the suction 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 is held in the state in which the injection port 5a is closed again. Fuel injection from 5a is stopped.

Next, the operation of the spark plug will be described. The high voltage from the ignition coil is transmitted to the valve seat 5 via the high tension cord 6, the screw stopper 7, the set screw 8, the pipe 61, the valve spring 9 and the valve 10, and the edge portion 5b of the valve seat 5 is used as a central electrode. And the GND electrode 12 facing it
A spark discharge is generated between and to ignite the mixture in the combustion chamber.

Next, the structure of the main part of the present invention in the fuel injection device will be described in detail with reference to FIG. 1A is a sectional view showing the peripheral portion of the valve tip, FIG. 1B is a sectional view taken along line BB of FIG. 1A, and FIG.
FIG. 7A is a sectional view taken along line CC of FIG. In the valve 10, the fuel guide portion 51 having the swirl forming screw groove 51a on the outer peripheral surface is integrally formed with the valve 10 by resin molding. Specifically, in the valve 10 itself, the shaft portion 50 excluding the fuel guide portion 51, the valve portion 52, and the slide portion 53 are formed of SUS440C material. The fuel guide portion 51 is provided on the relevant portion of the valve 10 itself.
The resin is molded to complete the valve 10. A flange portion 50a facing the upper end surface of the fuel guide portion 51 is formed on the shaft portion 50. Further, as the resin molding material of the fuel guide portion 51, a heat resistant resin material (for example, PPS resin material) is adopted.

According to the fuel injection device, the screw groove 5
By forming the fuel guide portion 51 having 1a integrally with the valve 10 by resin molding, the fuel guide portion 51 having a good dimensional accuracy can be easily manufactured at low cost as compared with the conventional case where the screw groove 51a is cut on the valve itself. Therefore, the fuel injection performance can be improved at a low cost. The valve itself has a screw groove 51a.
Since the processing is not required, the durability of the valve 10 can be ensured by adopting a hard material for the valve 10. Further, in the case where the spark plug is integrally formed with the fuel injection valve like the fuel injection device, the valve outer diameter cannot be made large due to the design of the fuel injection valve, but according to the present embodiment, there is such a valve 10. However, it is possible to easily form the fuel guide portion 51 that is small in size and has high dimensional accuracy at low cost, and thus it is possible to improve fuel injection performance at low cost and to make the apparatus compact. The present embodiment can be applied to a fuel injection device having no spark plug, that is, a general-purpose type fuel injection valve.

[0028]

According to the fuel injection device of the first aspect of the present invention, the fuel guide portion of the valve can be easily formed with high dimensional accuracy and at low cost, as compared with the case of cutting the screw groove on the valve itself. Therefore, the fuel injection performance can be improved at a low cost. According to the fuel injection device of the second aspect, the fuel guide portion of the valve in the fuel injection valve that integrally configures the spark plug can be easily formed with small size, high dimensional accuracy, and low cost. The injection performance can be improved at a low cost, and the device can be made compact.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a main part of a fuel injection device.

FIG. 2 is a cross-sectional view showing a fuel injection device.

FIG. 3 is an enlarged sectional view showing a tip portion of the fuel injection device.

FIG. 4 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 5 Valve seat 5a Injection port 10 Valve 51 Fuel guide part 51a Screw groove

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

Claims (2)

[Claims] 1. A fuel injection valve comprising a valve seat having a substantially hollow cylindrical shape and having an injection port at its tip, and a valve provided in the valve seat so as to be openable and closable in the axial direction,
In the fuel injection device, wherein the valve is provided with a fuel guide part having a swirl forming screw groove on its outer peripheral surface, the fuel guide part is integrally formed with the valve by resin molding. 2. The fuel injection valve is a fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine, and the fuel injection valve is integrally formed with an ignition plug. Fuel injector.