JPH08312497A - Fuel injection device - Google Patents

Abstract

PURPOSE: To enhance reliability for insulation by securing insulating properties at the connecting section of a high tension cord without depending on the filling condition of filling material. CONSTITUTION: The device is equipped with a fuel injection valve directly injecting fuel into the combustion chambers of an internal combustion engine, and with an ignition plug integrally formed with the fuel injection valve. The valve seat 5 of the fuel injection valve is made a central electrode, a conductive member at the central electrode side is formed out of electrically connected members 7, 8, 61, 9 and 10, and a high tension cord 6 is electrically connected to the conductive member 7. An earth electrode 12 is provided for a cap 11 which is disposed in the housing 20 of the fuel injection valve while being insulated from the central electrode 5. An insulating cylinder 41 is interposed between the conductive member 7 and the housing 20. The high tension cord 6 is connected to the conductive member 7 in the inside of the insulating cylinder 41.

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 fuel injection system includes a fuel injection valve for directly injecting fuel into a combustion chamber of an engine and an ignition plug integrally formed with the fuel injection valve. There is a device (for example, Shoukai 63-1547)
No. 60). In this type of fuel injection device, a conventional example to which the present invention is applied will be described with reference to the sectional view of FIG. Note that hatching showing a cross section is omitted in FIG. The fuel injection device shown in FIG. 2 is roughly divided into a housing sub-assembly (corresponding to a housing in the present invention) 20, a body sub-assembly 21, a valve sub-assembly 4 and a cap which are assembled to the housing sub-assembly 20. It is composed of a sub-assembly 23.

The housing sub-assembly 20 has an inner cylindrical body 34 and an outer cylindrical body 35 which have a substantially hollow cylindrical shape and which are double-inserted inside and outside. The inner cylinder 34 is made of SUS304 material, and the outer cylinder 35 is made of SUS magnetic material. The joint surface between the inner cylindrical body 34 and the outer cylindrical body 35 is axially communicated by mutual insertion and both ends in the axial direction (upper and lower ends in the drawing).
Is formed to open the fuel passage 33. Further, the outer cylindrical body 35 is provided with a stepped and expanded flange member 60 at the upper end thereof.

In the annular space formed around the inner cylinder 34 by the flange member 60 of the outer cylinder 35, SUS is formed.
A ring-shaped joint part 37 made of a material is rotatably fitted in a state in which a gap is maintained between the lower surface thereof and the bottom surface of the annular space portion. The joint part 37 is attached to the inner cylindrical body 34 by SU.
It is fixed by tightening the fixing nut 38 made of S303 material. 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 the fuel intake port 1, and a fuel supply pipe is connected to the opening on the outer side surface thereof. In addition, between the inner cylindrical body 34 and the joint component 37,
An O-ring (reference numeral omitted) is provided between the outer cylindrical body 35 and the joint component 37 to keep them airtight.

The body sub-assembly 21 incorporated by being inserted into the housing sub-assembly 20 is a second block 15 made of a SUS304 material having a ring shape.
And an insulating cylinder 41 made of a substantially hollow cylindrical electric insulating material (also referred to as an insulator), for example, polyphenylene sulfide resin (also referred to as PPS resin), in which the second block 15 is insert-molded in the central portion, and the insulating cylinder 41. A core 2 made of a magnetic material having a substantially hollow cylindrical shape fitted therein, a bobbin 16 made of an electrical insulating material such as PPS resin fitted in the core 2, and a coil 42 wound around the bobbin 16 in multiple layers. , A ring-shaped SU fitted on the lower end of the core 2
The first block 14 made of S304 material and the first block 14 made of S304 material are fitted in the yoke 17 made of SUS magnetic material having a substantially hollow cylindrical shape. In addition, between the insulating cylinder 41 and the core 2, the core 2 and the first
Between the blocks 14 and between the first block 14 and the yoke 17, they are hermetically held by O-rings (reference numerals omitted).

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 the yoke 17 in the radial direction. Further, the fuel passage formed by the groove 17 a and the outer cylindrical body 35 communicates with the fuel passage 33. A harness 43 is electrically connected to the coil 42 by soldering. 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. Further, the upper end portion of the second block 15 is fitted in the inner cylindrical body 34, and the fitting portions are airtightly held by an O-ring (reference numeral omitted).

In the upper end of the insulating cylinder 41, SUS3
A set screw 8 made of 03 material is inserted. The head of the set screw 8 is screwed onto the insulating cylinder 41, and the shaft portion and the insulating cylinder 41 are hermetically held by an O-ring (reference numeral omitted). Further, a lower end portion of a set screw stopper (referred to as screw stopper) 7 made of SUS303 material for fixing the set screw 8 is screwed into the upper end portion of the insulating cylinder 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. In the space portion (denoted by reference numeral 47) around the high tension cord 6 and the insulating cylinder 41 in the housing sub-assembly 20,
Filling material such as epoxy resin (not shown) is filled.

The valve sub-assembly 4 incorporated in the lower portion of the body sub-assembly 21 is a shaft-shaped valve 10 made of SUS440C material, and a valve support made of an electric insulating material such as PPS resin in which the upper end of the valve 10 is insert-molded. 48 and the armature 3 made of a magnetic material insert-molded on the outer peripheral portion of the valve support 48. The upper half of the valve support 48 is formed in a hollow cylindrical shape.

The valve sub-assembly 4 is vertically movably fitted into the body sub-assembly 21. Specifically, after inserting the valve spring 9 made of SUS304 material into the insulating cylinder 41, the cylindrical portion of the valve support 48 into which the lower end portion of the valve spring 9 is fitted is the insulating cylinder 4.
It is inserted in 1. By fitting the valve spring 9 into the tubular portion of the valve support 48, the lower end surface of the valve spring 9 is in contact with the upper end surface of the valve 10 that forms the bottom surface of the tubular portion. Also, the set screw 8
A pipe 61 made of SUS303 material is rotatably interposed between the valve spring 9 and the valve spring 9. The pipe 61 prevents twisting due to the rotation of the valve spring 9 when the set screw 8 is screwed.

The cap sub-assembly 23 incorporated in the lower end of the housing sub-assembly 20 has a substantially hollow cylindrical shape and a valve seat 5 made of a stainless alloy material having a nozzle 5a at its lower end and a substantially hollow cylindrical shape. And a ceramic insulating cover 13 in 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. That is, the cap 11 has the insulating cover 13 to cover the valve seat 5
And is arranged in an insulated state.

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.
A ground electrode (also referred to as a GND electrode) 12 that is directed to the is provided. Further, the cap 11 has a male screw 11a for screwing onto a cylinder head (not shown) of an internal combustion engine.
Are formed. The valve seat 5 and the insulating cover 1
3, the space between the insulating cover 13 and the cap 11 is hermetically held by an O-ring and a gasket (both not shown).

The cap sub-assembly 23 is incorporated in the housing sub-assembly 20, and more specifically, the valve 10 is slidably inserted into the valve seat 5, and the cap 11 is provided at the lower end of the outer cylinder 35. And is 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 10 is held in the closed state.

A cylindrical ring tube 18A made of metal, for example, SUS303 material is inserted into the cap 11 and faces the yoke 17. This ring cylinder 18A
A ring-shaped adjustment plate 22A made of metal, for example, SUS440C-based material is interposed between and the yoke 17 opposed thereto. The opening / closing stroke of the valve 10 is finely adjusted by adjusting the plate thickness of the adjusting plate 22A. Between the insulating cover 13 and the valve support 48, the communication hole 44 of the yoke 17 is inserted into the valve seat 5.
A fuel passage communicating with the inside is formed.

First, the operation of the fuel injection valve in the fuel injection device will be described. The fuel supplied from a fuel tank (not shown) in a state where a predetermined pressure is applied 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 in the closed state by the elasticity of the valve spring 9, the injection port 5 of the valve seat 5 is closed.
Fuel injection from a does not occur.

When the coil 42 is energized by inputting 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 valve 10 is opened, so that fuel is injected from the injection port 5a of the valve seat 5.
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 holds the valve 10 in the closed state again. Nozzle 5
The fuel injection from a 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, is transmitted to the valve seat 5 through the valve spring 9 and the valve 10, and spark discharge is generated between the edge portion 5b of the valve seat 5 and the ground electrode 12 facing the valve seat 5 as a central electrode to generate a mixture in the combustion chamber. Ignite. In addition, screw stop 7, set screw 8, pipe 6
1, the valve spring 9 and the valve 10 correspond to a conductive member that is arranged at the axial center of the fuel injection valve and is electrically connected to the valve seat 5 that is the center electrode. Further, the housing sub-assembly 20 is electrically connected to the cap 11 having the ground electrode 12. Further, a fuel injection device having a configuration substantially similar to the above is disclosed in, for example, Japanese Patent Application No. 7-23013 (not yet published at the time of filing of the present application) previously proposed by the same applicant.

[0017]

In the fuel injector, however, the socket portion 7a of the screw stopper 7 which is the conductive member on the side of the central electrode to which the high tension cord 6 is connected projects from the insulating cylinder 41. The high tension cord 6 and the screw stopper 7 are connected outside the insulating cylinder 41. The connecting portion and the housing sub-assembly 20 are insulated from each other by an insulating filling material such as an epoxy resin that fills the space 47 between them to fill the space.

As described above, in the conventional example, the insulating cylinder 41 is used.
Since the high tension cord 6 and the screw stopper (conductive member on the side of the center electrode) 7 are connected outside the cylinder of
The insulating property between the connecting portion and the housing sub-assembly 20 depends on the filling material filled in the space portion therebetween. Therefore, due to insufficient filling such as when the filling of the filling material is not successful, the space portion may not be completely filled and a gap may be generated, and it is difficult to ensure the insulation.

The technical problem to be solved by the present invention is as follows.
An object of the present invention is to provide a fuel injection device capable of improving the reliability of insulation by ensuring the insulation of the connection portion of the high tension cord without depending on the filling condition of the filler.

[0020]

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 integrally formed with the fuel injection valve are provided. And a valve seat (5) arranged at the tip of the fuel injection valve as a center electrode of the spark plug, and arranged at the axial center of the fuel injection valve and electrically connected to the center electrode (5). Connecting members (7,8,61,9,1
0) constitutes a conductive member on the side of the center electrode, a high tension cord (6) is electrically connected to the conductive member (7), and the center electrode is attached to the tip of the housing (20) of the fuel injection valve. A ground electrode (12) of a spark plug is provided on a cap (11) arranged in an insulated state from (5), and an insulator is provided between the conductive member (7) on the center electrode side and the housing (20). A fuel injection device provided with a cylindrical insulating cylinder (41), characterized in that the high tension cord (6) and the conductive member (7) are connected in the cylinder of the insulating cylinder (41). It is a fuel injection device.

[0021]

According to the fuel injection device of the first aspect, the high tension cord (6) and the conductive member (7) on the side of the central electrode (5) are connected in the insulating cylinder (41).
The connecting portion fits within the cylinder of the insulating cylinder (41).

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel injection device according to an embodiment of the present invention will be described with reference to the sectional view of FIG. In FIG. 1, hatching showing a cross section is omitted. In addition, since the present embodiment is a modification of a part of the conventional example (see FIG. 2), only the modified part will be described in detail, and the same or substantially the same parts will be denoted by the same reference numerals and overlap. The description is omitted. In FIG. 1, the high tension cord 6 and the screw stopper 7, which is a conductive member on the side of the center electrode, are connected inside the insulating cylinder 41. Specifically, the upper end portion of the insulating cylinder 41 in the conventional example (see FIG. 2) is extended upward (this extended portion is denoted by reference numeral 41a).

Further, the screw stopper 7 has a short axial length. In comparison with the conventional example, the screw stopper 7 shown in FIG. 1 has a short axial length of the socket portion 7a, so to speak, and is itself screwed to the insulating cylinder 41. The set screw 8 has a short axial length and the pipe 61 has a long axial length. The harness 4 of this example
A shield material 59 made of a material having excellent conductivity, such as a copper foil or an aluminum foil, is wound around the wire 3. A space (denoted by reference numeral 47) around the high tension cord 6 and the insulating cylinder 41 in the housing sub-assembly 20 is filled with a filler (not shown) such as an epoxy resin as in the conventional example. And

According to the fuel injection device, since the high tension cord 6 and the screw stopper 7, which is a conductive member on the side of the center electrode, are connected in the cylinder of the insulating cylinder 41, the connecting portion fits in the cylinder of the insulating cylinder 41. As a result, the insulation property of the connection portion between the high tension cord 6 and the screw stopper 7 is ensured by the insulation cylinder 41. Therefore, as compared with the conventional one which relies on the filling with the filling material, the one having high insulation reliability can be obtained.

[0025]

According to the fuel injection device of claim 1,
Since the insulation property of the connection portion between the high tension cord and the conductive member on the side of the center electrode is secured by the insulating cylinder, the reliability of insulation can be improved as compared with the conventional method which depends on the filling of the filling material.

[Brief description of drawings]

FIG. 1 is a sectional view showing a fuel injection device according to an embodiment of the present invention.

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

[Explanation of symbols]

 5 Valve seat (center electrode) 6 High tension cord 7 Screw stopper (center electrode side conductive member) 8 Set screw (center electrode side conductive member) 9 Valve spring (center electrode side conductive member) 10 Valve (center electrode side) Conductive member of 11) Cap 12 Ground electrode 20 Housing sub-assembly (housing) 41 Insulating cylinder 61 Pipe (conductive member on the center electrode side)

Claims (1)

[Claims] 1. A valve seat provided with 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, the valve seat being arranged at a tip portion of the fuel injection valve. As the center electrode of the spark plug,
A member disposed on the axial center of the fuel injection valve and electrically connected to the center electrode constitutes a conductive member on the side of the center electrode, and a high tension cord is electrically connected to the conductive member. A grounding electrode of a spark plug is provided on a cap disposed in a state of being insulated from the center electrode at a front end portion of the housing, and a cylindrical insulating cylinder made of an insulator is provided between the conductive member on the center electrode side and the housing. A fuel injection device provided with: a fuel injection device, wherein the high tension cord and a conductive member are connected in a tube of the insulating tube.