JP3219959B2 - Fuel injection device - Google Patents

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 for an internal combustion engine for a vehicle.

[0002]

2. Description of the Related Art A conventional fuel injection device includes a fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine, and a spark plug integrally formed with the fuel injection valve (for example, a fuel injection device which is actually open). See JP-A-63-154760). The fuel injection device disclosed in the above publication will be described with reference to the sectional view of FIG. The housing 101 is made of a conductor having a screw portion that fits into a cylinder head of an engine (not shown). A ground electrode 102 is attached to the tip of the housing 101. Inside the housing 101, an inner body 103 having a valve seat 104 and a fuel passage 105 is provided. The movable shaft 106 having a valve portion 106b for opening and closing the valve seat 104 has a center electrode 106a at a lower end thereof and a spring seat 106c at an upper end thereof. In the inner body 103, a bearing 107a of the movable shaft 106 is provided.
And a yoke 107 provided with an electromagnetic coil 109 is provided. A first spring 108 is inserted between the spring seat 106c of the movable shaft 106 and the yoke 107. The yoke 107 is provided with a holder 110 for holding an electrode 111. The housing 101 is provided with a holding part 112a for holding the electrode 111, a plastic body 112 having a fuel supply port 112b and a connector housing 112c. The electrode 1
A second spring 114 is inserted between the spring 11 and the spring seat 106c. A terminal 115 is connected to a coil end of the electromagnetic coil 109.

In the fuel injection device, the electrode 111, the second
Of the center electrode 10 via the spring 114 and the movable shaft 106
An electric spark is generated by discharging the power supplied to 6a to the ground electrode 102. On the other hand, by the electromagnetic coil 109 excited by energization from the terminal 115,
The movable shaft 106 is sucked in the direction of compressing the first spring 108, and the valve portion 106b is separated from the valve seat 104, so that the fuel that has reached the valve seat 104 via the fuel supply port 112b and the fuel passage 105 is injected. You.

[0004]

The fuel injection valve in the conventional fuel injection device is of an external valve type in which a movable shaft 106 corresponding to the valve is closed by retreating and is opened by advancement. In such an external valve type, in order to secure the sealing force of the valve accompanying the increase in the fuel pressure, the spring force of the first spring 108 needs to be increased, and the electromagnetic attraction force increases accordingly. This necessitates an increase in the size of the device. For these reasons, in order to reduce the size of the device, it is preferable to configure the fuel injection valve to be an internal valve that opens when the valve is retracted and closes when it is advanced, as opposed to the external valve. By the way, in the case of adopting the inner-valve type, a valve seat (in FIG. 7, the inner body 103 corresponds to the one shown in FIG. 7) having a movable valve has a function of the center electrode of the ignition plug. For this reason, a material having high hardness that is not easily deformed by heat is required for the valve seat. For example, use of an Inconel material which is a heat-resistant alloy is considered. However, since the Inconel material contains a large amount of nickel, it is difficult to perform machining such as cutting, and therefore, there is a problem that machining accuracy sufficient to secure the performance of the fuel injection valve cannot be obtained. If a material having better workability than the Inconel material is used, dissatisfaction remains in the heat resistance and spark wear resistance at the ignition site.

The technical problems to be solved by the present invention are:
Fuel injection that can secure the heat resistance and spark wear resistance of the ignited part while increasing the processing accuracy of the valve seat that becomes the center electrode when configuring the fuel injection valve that has an integrated spark plug as an internal valve type It is to provide a device.

[0006]

According to a first aspect of the present invention, there is provided a fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine, and a spark plug integrally formed with the fuel injection valve. The fuel injection valve has an inner opening type in which a valve provided to be movable forward and backward is provided in a valve seat having an injection port at a front end so as to move forward and backward, and is closed by moving forward. In the fuel injection device as an electrode, the ignition portion of the valve seat is formed of a material having higher heat resistance and spark erosion resistance than the material of the valve seat itself, and the valve seat itself is more workable than the material of the ignition site. This is a fuel injection device made of a heat-resistant material having excellent heat resistance. The invention according to claim 2 is the fuel injection device according to claim 1, wherein the valve seat itself is formed of a stainless steel material, and the ignition portion of the valve seat is coated with a Ni alloy material containing 70% by weight or more of Ni.

[0007]

According to the fuel injection device of the first aspect of the invention, when the fuel injection valve integrally provided with the ignition plug is configured to be an internal valve type, the valve seat itself serving as the center electrode is more workable than the ignition portion. Since it is formed of an excellent heat-resistant material, it is possible to perform high-precision processing sufficient to secure the performance of the fuel injection valve. In addition, the ignition portion of the valve seat is made of a material that has better heat resistance and spark wear resistance than the valve seat itself, so it is necessary to ensure heat resistance enough to withstand high heat and wear resistance due to spark discharge. Can be. According to the fuel injection device of the second aspect of the present invention, the valve seat itself made of stainless steel is excellent in workability as compared with a Ni alloy material containing 70% by weight or more of Ni, such as an inconel material, so that high-precision processing is performed. can do. The Ni alloy material containing 70% by weight or more of Ni coated on the ignition portion of the valve seat is superior in heat resistance and spark wear resistance as compared with stainless steel material. Nature can be secured.

[0008]

An embodiment will be described with reference to the drawings. In FIG. 1 showing a cross-sectional view of the fuel injection device, the fuel injection device is roughly divided into a substantially hollow cylindrical housing sub-assembly 20 and a housing sub-assembly 20.
, A valve sub-assembly 4, a valve sub-assembly 4 and a cap sub-assembly 23. In FIG. 1, hatching indicating a cross section is omitted.

As shown in the sectional view of FIG. 2, the housing sub-assembly 20 has an inner cylindrical body 34 and an outer cylindrical body 35 which are formed in a substantially hollow cylindrical shape and which are inserted inside and outside. For more information,
The inner cylinder 34 made of SUS304 material is inserted into almost the upper half of the outer cylinder 35 made of SUS-based magnetic material.
An appropriate number of grooves 34a are provided on the outer peripheral surface of the insertion portion along the axial direction. The groove 34a is formed in the outer cylinder 3
By closing the outer peripheral surface by the insertion of 5,
A fuel passage that opens at both axial ends (upper and lower ends in the figure) is formed. The upper end of the outer cylinder 35 is formed in a stepped and expanded shape.

As shown in FIG. 1, a ring-shaped joint part 37 is rotatably provided in the annular space formed between the upper ends of the cylindrical bodies 34 and 35, and the lower surface thereof is connected to the annular space. It is fitted in a state where a gap is kept between the bottom of the part. The joint part 37 is made of a SUS material, and is fixed by tightening a fixing nut 38 made of a SUS303 material and screwed to the upper end of the inner cylindrical body 34. The joint part 37 is formed with a fuel inlet 1 having one end opened on the outer side and the other end opened on the lower side. A strainer 39 is incorporated at the inlet of the fuel inlet 1, while a fuel supply port is provided. Piping is connected. In addition, the O-ring 30 for maintaining the airtightness between the joint part 37 and the peripheral surface of each cylindrical body,
31 are provided respectively.

A body sub-assembly 21 is incorporated in the housing sub-assembly 20. As shown in the sectional view of FIG. 3, the body sub-assembly 21 has a ring-shaped second block 15 made of SUS304 material, and a substantially hollow cylindrical electric body formed by insert-molding the second block 15 on the outer periphery of the center. A spring guide 41 made of an insulating material such as polyphenylene sulfide resin (also referred to as PPS resin), and a core 2 made of a substantially hollow cylindrical magnetic material fitted into the spring guide 41 from below.
And an electrical insulating material, such as P, fitted on the outer peripheral surface of the core 2.
A bobbin 16 made of PS resin, a coil 42 wound around the bobbin 16 in a multilayer shape, and a first block 14 made of a ring-shaped SUS304 material fitted on the outer peripheral surface of the lower end of the core 2 are provided. These are fitted from above into a yoke 17 made of a SUS-based magnetic material having a substantially hollow cylindrical shape, and the upper end edge of the yoke 17 is placed in the second block 15.
I crouch. The spring guide 41 is provided with an O-ring 27 for maintaining 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. In this example, as shown in FIG. 4, which is an enlarged cross-sectional view taken along the line AA in FIG. 3, four grooves 17a are formed at equal intervals in the circumferential direction. In FIG. 4, a coil harness 43 (described later) is omitted. The groove 17a opens at the upper end surface of the yoke 17 as shown in FIG.
Is connected to a communication hole 44 penetrating in the radial direction of the yoke near the lower end portion.

A terminal 45 to which the coil 42 is electrically connected protrudes from the upper end surface of the bobbin 16 and passes through the flange of the core 2 to form the recess 1 of the second block 15.
Intervened within 5a. In the recess 15a,
The terminal 45 has a harness 43 drawn between the second block 15 and the spring guide 41.
Are electrically connected.

As shown in FIG. 1, the body sub-assembly 21 is inserted into the lower half of the housing sub-assembly 20 from below. With this insertion, the harness 43 is drawn upward through the inner cylinder 34 of the housing sub-assembly 20. The harness 43 is connected to an electronic control unit (also referred to as an ECU) (not shown), and is energized and released by receiving an input from the electronic control unit with the coil 42.

The groove 17a of the yoke 17 forms a fuel passage when its outer peripheral surface is closed by the insertion of the outer cylindrical body 35. This fuel passage is provided in the inner cylinder 34,
The groove 3 of the inner cylinder 34 is formed through a space surrounded by the outer cylinder 35, the yoke 17, and the second block 15.
It communicates with the fuel passage 4a. The upper end of the second block 15 is fitted to the inner cylinder 34. The second
The block 15 is provided with an O-ring 28 for maintaining airtightness between the block 15 and the inner cylinder 34.

At the upper end of the spring guide 41, a set screw 8 made of SUS303 material and a set screw stopper (referred to as a screw stopper) 7 are sequentially screwed. More specifically, the head of the set screw 8 having the groove portion 8a is screwed to the spring guide 41, and the tip of the shaft portion contacts the upper end surface of the valve spring 9 described later. The screw stopper 7 has its lower end screwed to a spring guide 41, and the upper end of the screw stopper 7 has a rectangular groove-shaped socket part 7.
The socket portion 7a is electrically connected to the connection terminal 6a of the high tension cord 6 inserted into the inner cylinder 34 from above. Set screw 8
Has O to maintain airtightness with the spring guide 41.
A ring 29 is provided. A filler 46 such as an epoxy resin for sealing a space around the high tension cord 6 and the harness 43 is loaded on the upper end of the inner cylinder 34.

At the lower end of the body sub-assembly 21, a valve sub-assembly 4 is incorporated. As shown in the sectional view of FIG. 5, the valve sub-assembly 4 includes a valve 10 made of a SUS440C material having a substantially axial shape, and a valve support made of an electric insulating material such as PPS resin formed by insert-molding the upper end of the valve 10. And an armature 3 made of a magnetic material insert-molded on the outer periphery of the central portion of the valve support 48. The valve support 4
The upper half of 8 has a hollow cylindrical shape with the upper end surface of the valve 10 as the bottom surface. The valve 10 has a shaft 5
A fuel guide portion 51 which is formed in a substantially cylindrical shape at the distal end of the fuel guide 51 and has a screw groove 51a on the outer peripheral surface thereof, and a substantially conical valve element 52 provided at the distal end of the fuel guide portion 51
And a flange-shaped slide portion 53 formed at the center of the shaft portion 50.

As shown in FIG. 1, the valve sub-assembly 4 is inserted into a body sub-assembly 21 so as to be vertically movable from below. For details, see the spring guide 41
A valve spring 9 made of SUS304 material is inserted into the inside, and a valve support 4 is attached to the lower end of the valve spring 9.
8, the upper end of the valve support 48 is fitted in the spring guide 41 and the armature 3 is fitted in the lower end of the yoke 17. The armature 3 has the upper end surface of the core 2
And receives an attractive force from the core 2 when the coil 42 is energized. The inner end opening of the communication hole 44 of the yoke 17 communicates with a space around the valve support 48 below the armature 3.

At the lower end of the housing sub-assembly 20, a cap sub-assembly 23 is incorporated. As shown in the sectional view of FIG. 6, the cap sub-assembly 23 has a substantially hollow cylindrical shape and has a nozzle 5a at its lower end.
A ceramic cover 13 having a substantially hollow cylindrical shape and having the valve seat 5 inserted and screwed therein, and a substantially hollow cylindrical shape having the cover 13 inserted therein. And a cap 11 made of a SUS-based material. At the lower end of the cap 11, a ground electrode 12 made of a Ni alloy material and having its tip directed toward the lower edge 5b of the valve seat 5 is provided. On the outer peripheral surface of the cap 11, a male screw 11a for screwing to a cylinder head of an internal combustion engine is provided.
Are formed. The valve seat 5 has a cover 13.
An O-ring 19 for maintaining airtightness between the cap 11 and the O-ring 19 is provided on the cover 13.
A ring 24 is provided. The upper edge of the cap 11 is swaged to the 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 cover 13 and between the cover 13 and the cap 11.

In the valve seat 5, the valve seat 5 itself is made of stainless steel (for example, SUS44).
0C) and an inconel material (for example, JIS)
NCF 751) is sprayed to form an ignition site. The stainless steel material SUS440C has a heat resistance of up to 500 ° C. and a hardness of 65 ° C.
It exhibits characteristics such as 0 Hv, a resistivity of 60 μΩcm, and good conductivity. Inconel material NCF751 has a heat resistance of up to 980 ° C. and a hardness of 3%.
50 Hv, a resistivity of 122 μΩcm, good conductivity, and excellent resistance to spark abrasion compared to SUS440C. The hardness of NCF751 is smaller than that of SUS440C, but the workability of NCF751 is lower than that of SUS440C since NCF751 contains 70% by weight or more of nickel.
Bad compared to 40C. Inconel materials usable for thermal spraying include NCF750, NCCF750
F80A, etc., Ni-Si-Mn alloy, Ni
-Si-Mn-Cr alloy, Ni-Si-Mn-Cr-A
An Ni alloy material containing 70% by weight or more of Ni, such as a 1 alloy, is useful in terms of spark wear resistance. That is, the edge portion 5b, which is the ignition portion of the valve seat 5, is formed of a material having higher heat resistance and spark erosion resistance than the material of the valve seat 5 itself, and the valve seat 5 itself is more workable than the material of the ignition portion. It is made of a heat-resistant material with excellent heat resistance. In addition, not only thermal spraying but also CVD, plating, and flakes may be applied to the ignition site by welding or the like.

The cap sub-assembly 23 is inserted into the lower end of the housing sub-assembly 20, as shown in FIG. Specifically, the valve 10 is slidably inserted into the valve seat 5, and the cap 11 is fitted to the lower end of the outer cylinder 35 and fixed by laser welding. Valve sub assembly 4
Is constantly urged downward in the figure by the elasticity of the valve spring 9, and the valve element 52 of the valve 10 is kept in a state in which the injection port 5a of the valve seat 5 is closed. Valve 1
The zero slide portion 53 has a substantially circular shape which is slidably fitted in the valve seat 5 and forms a fuel passage portion which is opened in the axial direction by partially cutting off the outer peripheral portion thereof.

The cover 13 and the yoke 1 facing the cover 13
A ring-shaped stroke adjusting plate 22 made of a SUS440C-based material is interposed between the seven portions. The inner diameters of the stroke adjusting plate 22 and the upper end of the cover 13 are formed larger than the large diameter portion of the valve support 48, and the yoke 17 is provided between the plate 22 and the cover 13 and the valve support 48. A fuel passage communicating from the communication hole 44 into the valve seat 5 is formed.

The opposite ends of the cap 11 and the yoke 17 are coaxially connected by press-fitting both ends of a concentricity securing ring 18 made of SUS303 material having a cylindrical shape. The O-rings 19, 24 to 32 used for the respective parts are all made of a fluoro rubber material. Further, the material specified for each member is not limited thereto, and may be any material that satisfies the conditions required for each member.

The fuel injection device constructed as described above has
The fuel injection valve includes a fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine, and a spark plug integrally formed with the fuel injection valve. First, the operation of the fuel injection valve will be described.
Fuel supplied under a predetermined pressure from a fuel tank (not shown) is filtered by a strainer 39 of a fuel inlet 1 and then passes through a fuel passage to a valve seat 5.
Inside. However, due to the elasticity of the valve spring 9, the valve 10 is provided with the injection port 5a of the valve seat 5.
Is kept in a closed state, so that fuel injection from this injection port 5a does not occur.

When the coil 42 is turned on by the input of an electric signal from the electronic control unit, the valve sub-assembly 4 having the armature 3 is retracted by the attraction of the core 2 as described above. As a result, valve 1
0 opens the injection port 5a of the valve seat 5, from which fuel is injected. Then, when the electric signal to the coil 42 is turned off and the suction force of the core 2 acting on the armature 3 is released, the valve sub-assembly 4 advances due to the elasticity of the valve spring 9, and the valve 10 returns to the injection port 5.
a is kept closed, and the fuel injection from the injection port 5a stops.

Next, the operation of the ignition plug will be described.
The high voltage from the ignition coil is transmitted to the valve seat 5 via the high tension cord 6, screw stopper 7, set screw 8, valve spring 9, and valve 10, and the valve seat 5 is used as a central electrode to form an edge portion 5b and the like. Spark discharge is caused between the ground electrode 12 and the air-fuel mixture in the combustion chamber.

According to the fuel injection device, the valve seat 5 itself, which becomes the center electrode when the fuel injection valve integrally provided with the ignition plug is configured to be the inner valve type, is made of stainless steel material which is more excellent in workability than the edge portion 5b. Therefore, high-precision processing sufficient to secure the performance of the fuel injection valve can be performed. In addition, since the edge portion 5b, which is the ignition portion of the valve seat 5, is formed of an Inconel material having better heat resistance and spark erosion resistance than the valve seat 5 itself, heat resistance and spark resistance that can sufficiently withstand exposure to high heat. Consumability can be ensured. Therefore, it is possible to secure the heat resistance and the spark erosion resistance of the ignition portion while increasing the processing accuracy of the valve seat 5.

Further, the valve seat 5 itself is excellent in workability as compared with a Ni alloy material containing 70% by weight or more of Ni.
Ancillary effects such as reduction in processing costs can also be expected. Further, since the ignition portion is formed by covering the edge portion 5b with a Ni alloy material containing 70% by weight or more of Ni, the manufacturing cost can be reduced as compared with the case where the ignition portion formed of a separate part is retrofitted to the sheet 6 itself. Can be planned.

[0029]

According to the fuel injection device of the first aspect of the present invention, when the fuel injection valve integrally provided with the ignition plug is configured to be an open valve type, ignition is performed while increasing the processing accuracy of the valve seat serving as the center electrode. Heat resistance and spark wear resistance of the part can be ensured. According to the fuel injection device of the second aspect of the invention, the performance of the fuel injection valve can be ensured by performing high-precision processing by forming the valve seat itself from stainless steel, and the ignition portion of the valve seat can be reduced. The heat resistance required for the ignition portion of the spark plug is obtained by forming the Ni alloy material containing 70% by weight or more of Ni.
Spark erosion resistance can be ensured.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a housing sub-assembly.

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

FIG. 4 is an enlarged cross-sectional view taken along line AA of FIG. 3;

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 a sectional view showing a conventional example.

[Explanation of symbols]

 5 Valve seat 5a Injection port 5b Edge (ignition site) 10 Valve

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-19142 (JP, A) JP-A-8-218971 (JP, A) Japanese Utility Model Sho 54-95617 (JP, U) Japanese Utility Model Sho 61- 142168 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 57/06 F02P 13/00 303 F02M 51/06 F02M 61/16 F02M 61/18 360

Claims (2)

(57) [Claims] 1. A fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine, and a spark plug integrally formed with the fuel injection valve, wherein the fuel injection valve has an injection port at a front end of a valve seat. In a fuel injection device in which a valve provided to be able to move forward and backward is opened by retreating and closed by advancement thereof, and the valve seat is a central electrode of a spark plug, the ignition portion of the valve seat is A fuel injection device characterized in that the valve seat itself is formed of a heat-resistant material that is more excellent in workability than the material of the ignition portion, the material being formed of a material having better heat resistance and spark erosion resistance than the material of the valve seat itself. 2. The valve seat itself is formed of a stainless steel material, and 70% by weight of Ni is contained in an ignition portion of the valve seat.
2. The fuel injection device according to claim 1, wherein the fuel injection device is coated with a Ni alloy material containing the above.