JPH08218971A - Fuel injection device - Google Patents

Abstract

PURPOSE: To secure an adequate shutoff property of a valve so as to prevent fuel spill by screwing a set screw regulating spring force of a valve spring into a spring guide inside a core and screwing up a screw stopper for fixing the set screw in a regulation position. CONSTITUTION: A core 2 is surrounded by a bobbin 16, while a coil 42 is wound on the bobbin 16. An armature 3 attracted to the core 2 by means of excitation of the coil 42 is arranged in a valve 10, by which an injection port 5a of a valve seat 5 is opened/closed. A valve spring 9 energizing the valve 10 in the valve closing direction is arranged in the core 2, while a spring guide 41 in which the valve spring 9 is arranged is provided, and a set screw 8 and a screw stopper 7 are screwed into the spring guide 41. In this way, spring force of the valve spring 9 can be finely regulated, and an adequate shutoff property of the valve can be secured, and consequently, fuel spill can be prevented.

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 Some conventional fuel injection devices have 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 (for example, actual opening). (See Japanese Patent Laid-Open No. 63-154760). The fuel injection device of 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 GND 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 its lower end and a spring seat 106c at its upper end. In the inner body 103, the bearing portion 107 of the movable shaft 106 is provided.
a having a and having an electromagnetic coil 109
Is provided. Spring seat 106c of the movable shaft 106
A first spring 108 is inserted between the yoke 107 and the yoke 107. The yoke 107 is provided with a holder 110 that holds an electrode 111. The housing 101 is provided with a plastic body 112 having a holding portion 112a for holding the electrode 111, a fuel supply port 112b, and a connector housing 112c. The electrode 1
A second spring 114 is inserted between 11 and the spring seat 106c. At the coil end of the electromagnetic coil 109,
The terminal 115 is connected.

In the above fuel injection device, the electrode 111 and the second
Via the spring 114 and the movable shaft 106 of the center electrode 10
An electric spark is generated by discharging the electric power applied to 6a to the GND electrode 102. On the other hand, Terminal 115
The movable shaft 106 is attracted in the direction of compressing the first spring 108 by the electromagnetic coil 109 that is excited by the energization from, and the valve portion 106b is separated from the valve seat 104, so that the fuel supply port 112b and the fuel passage 105 are closed. The fuel that has reached the valve seat 104 is injected therethrough.

[0004]

According to the conventional fuel injection device, there is no means for finely adjusting the spring force of the first spring 108 for biasing the movable shaft 106 in the valve closing direction. The movable shaft 106 corresponds to the valve in the present invention,
The first spring 108 also corresponds to a valve spring. Therefore, the spring force of the first spring 108 cannot be finely adjusted to ensure the proper shutoff property of the movable shaft 106. For example, if the spring force is less than an appropriate value, the movable shaft 106 is unnecessarily opened due to the influence of the pressure fluctuation of the combustion chamber of the internal combustion engine, causing fuel dripping,
On the contrary, if the spring force is larger than the proper value, the electromagnetic attraction force for opening the movable shaft 106 will be insufficient and the operation response will be deteriorated.

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 finely adjusting the spring force of a valve spring, ensuring proper shutoff of the valve, preventing fuel dripping, and improving operation response.

[0006]

According to the invention of claim 1, which solves the above-mentioned problems, a cylindrical core, a bobbin surrounding the outer periphery of the core, a coil wound around the bobbin, and a coil are energized. A valve having an armature that is sucked into the core, a valve seat having an injection port that is opened and closed by the valve, and a valve spring that urges the valve in a valve closing direction are provided, and fuel is directly supplied to a combustion chamber of an internal combustion engine. In a fuel injection device having a fuel injection valve for injecting and an ignition plug integrally formed with the fuel injection valve with the valve seat as a center electrode, a substantially hollow cylindrical shape in which the valve spring is housed in the core. Is provided with a set screw for adjusting the spring force of the valve spring, and Ttosukuryu a fuel injection device attached screw the screw stopper for fixing at the adjusted position the.

[0007]

According to the fuel injection device of the first aspect of the invention, the spring force of the valve spring is finely adjusted by rotating the set screw, and then the screw stopper is tightened to bring the set screw to the adjustment position. Fixed. As a result, it is possible to ensure an appropriate shutoff property of the valve, prevent fuel dripping due to insufficient spring force, and avoid a decrease in operating response due to excessive spring force. Further, by fixing the set screw by fixing the screw, unexpected loosening of the set screw due to valve operation is prevented for a long period of time.

[0008]

EXAMPLES Examples will be described with reference to the drawings. In FIG. 1, which is a 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, and the housing sub-assembly 20.
It is composed of a body sub-assembly 21, a valve sub-assembly 4 and a cap sub-assembly 23, which are assembled to each other. Note that hatching showing a cross section is omitted in FIG.

As shown in the sectional view of FIG. 2, 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 and attached to almost the upper half of the outer cylindrical body 35 made of SUS 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 provided on the outer cylinder 3
By closing the outer peripheral surface by inserting 5,
A fuel passage is formed which is open at both axial ends (upper and lower ends in the drawing). Further, the upper end portion of the outer cylindrical body 35 is formed in a stepped and expanded shape.

As shown in FIG. 1, a ring-shaped joint part 37 is rotatably formed in the annular space formed between the upper ends of the cylindrical bodies 34 and 35, and the lower surface thereof and the annular space. It is fitted with a gap maintained between it and the bottom surface of the part. The joint part 37 is made of SUS material, and is fixed by tightening a fixing nut 38 made of SUS303 material screwed to the upper end portion of the inner cylindrical body 34. The joint part 37 is formed with a fuel intake port 1 having one end opening on the outer peripheral surface and the other end opening on the lower surface. A strainer 39 is incorporated into the inlet part of the fuel intake port 1 while supplying fuel. The pipe is connected. The joint component 37 includes an O-ring 30, which maintains airtightness between the tubular body and the peripheral surface thereof.
31 are provided respectively.

A body sub-assembly 21 is incorporated in the housing sub-assembly 20. As shown in the cross-sectional view of FIG. 3, the body sub-assembly 21 includes a second block 15 made of a ring-shaped SUS304 material, and a substantially hollow cylindrical electric body formed by insert molding the second block 15 on the outer periphery of the central portion. 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 fitted to the outer peripheral surface of the core 2, for example P
A bobbin 16 made of PS resin, a coil 42 wound around the bobbin 16 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 are provided. And the upper end edge of the yoke 17 is fitted into the second block 15 from above.
It is crimped. The spring guide 41 is provided with 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. In this example, as shown in FIG. 4, which is an enlarged cross-sectional view taken along the line AA of FIG. 3, four groove lines 17a are formed at equal intervals in the circumferential direction. In FIG. 4, the coil harness 43 (described later) is omitted. As shown in FIG. 3, the groove 17a opens to the upper end surface of the yoke 17, while the lower end of the groove 17a has the yoke 17a.
Is connected to a communication hole 44 penetrating in the radial direction of the yoke near the lower end of the.

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

The body sub-assembly 21 is inserted into the lower half of the housing sub-assembly 20 from below as shown in FIG. With this insertion, the harness 43 is pulled out upward through the inner cylindrical body 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 the coil 42 receives an input from the electronic control unit to energize and deenergize the harness.

Further, the groove 17a of the yoke 17 forms a fuel passage by closing the outer peripheral surface of the outer cylindrical body 35 by inserting and mounting it. This fuel passage is formed by the inner cylinder 34,
The groove 3 of the inner cylindrical body 34 is provided through a space surrounded by the outer cylindrical body 35, the yoke 17 and the second block 15.
4a communicates with the fuel passage. The upper end of the second block 15 is fitted in the inner cylindrical body 34. The second
The 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. More specifically, the set screw 8 has a head portion having a groove portion 8a itself screwed onto a spring guide 41, and a tip end of a shaft portion thereof contacts an upper end surface of a valve spring 9 described later. The lower end portion of the screw stopper 7 is screwed onto the spring guide 41, and the upper end portion of the screw stopper 7 has a square groove-shaped socket portion 7.
a is formed, and the socket 7a is electrically connected to the connection terminal 6a of the high tension cord 6 inserted into the inner cylindrical body 34 from above. Set screw 8
O for maintaining airtightness with the spring guide 41.
A ring 29 is provided. In addition, a filling material 46 such as an epoxy resin that seals the space around the high tension cord 6 and the harness 43 is loaded on the upper end of the inner cylindrical body 34.

A valve sub-assembly 4 is incorporated in the lower end of the body sub-assembly 21. As shown in the sectional view of FIG. 5, the valve sub-assembly 4 includes a valve 10 made of a substantially shaft-shaped SUS440C material, and a valve support body made of an electrical insulating material such as PPS resin in which the upper end portion of the valve 10 is insert-molded. 48 and the 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 whose bottom surface is the upper end surface of the valve 10. Further, the valve 10 has a shaft portion 5
No. 0, a fuel guide portion 51 formed in a substantially cylindrical shape and having a screw groove 51a on its outer peripheral surface, and a substantially conical valve portion 52 provided at the tip portion of the fuel guide portion 51.
And a flange-shaped slide portion 53 formed in the central portion of the shaft portion 50.

As shown in FIG. 1, the valve sub-assembly 4 is fitted in the body sub-assembly 21 so as to be vertically movable from below. Specifically, the spring guide 41
A valve spring 9 made of SUS304 material is inserted in the inside, and the valve support 4 is attached to the lower end of the valve spring 9.
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 in a state where the upper cylindrical portion 8 is fitted. The upper end surface of the armature 3 is the core 2
Of the core 42, and receives a suction 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 the space around the valve support 48 below the armature 3.

A cap sub-assembly 23 is incorporated at the lower end of the housing sub-assembly 20. As shown in the cross-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.
Valve seat 5 made of NCF 713 or 718 material, and a ceramic cover 13 having a substantially hollow cylindrical shape and having the valve seat 5 inserted therein, and a substantially hollow cylindrical shape having the cover therein. And a cap 11 made of a SUS material in which 13 is inserted. 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. Also cap 1
On the outer peripheral surface of 1, a male screw 11a for screwing to 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 crimped to the cover 13 via an O-ring 32. Gaskets 54 and 55 made of copper are interposed between the valve seat 5 and the cover 13 and between the cover 13 and the cap 11.

The cap sub-assembly 23 is attached to 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 portion of the outer tubular body 35 and fixed by laser welding. The valve sub-assembly 4 is constantly urged downward in the drawing by the elasticity of the valve spring 9, and the valve element portion 52 of the valve 10 is connected to the injection port 5 of the valve seat 5.
It is held in a closed state. 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. .

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

The opposite ends of the cap 11 and the yoke 17 are coaxially connected by press-fitting both ends of a coaxiality ensuring ring 18 made of a cylindrical SUS303 material. The O-rings 19 and 24 to 32 used for the above-mentioned parts 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.

The fuel injection device constructed as described above is
The fuel injection valve has a fuel injection valve that directly injects fuel into a combustion chamber of an internal combustion engine, and an ignition plug integrally formed with the fuel injection valve. First, the operation of the fuel injection valve 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 intake port 1 and then passes through the fuel passage to the valve seat 5
Has reached inside. However, the valve 10 has the injection port 5a of the valve seat 5 due to elasticity of the valve spring 9.
Is maintained in a closed state, 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 having the armature 3 retracts due to the attraction force of the core 2 as described above. As a result, valve 1
0 opens the injection port 5a of the valve seat 5, and fuel is injected from here. 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 again causes the injection port 5
A is kept closed, and 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 transmitted to the valve seat 5 via the high tension cord 6, the screw stopper 7, the set screw 8, the valve spring 9 and the valve 10, and the valve seat 5 is used as a central electrode for the edge portion 5b and Spark discharge is generated between the opposing GND electrodes 12 to ignite the air-fuel mixture in the combustion chamber.

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.
Then, the valve sub-assembly 4 is inserted into the body sub-assembly 21, and the stroke adjusting plate 22 is set in the yoke 17. (3) Insert the cap sub-assembly 23 into the housing sub-assembly 20. At this time, the thickness of the stroke adjusting plate 22 is adjusted so that the opening / closing stroke of the valve sub-assembly 4 becomes appropriate. (4) Then, once, the housing sub-assembly 20
Remove each sub-assembly from the body and insert the body sub-assembly 2
The yoke 17 of No. 1 and the end portion of the cap 11 of the cap sub-assembly 23 are connected to each other by press-fitting the ring 18 for securing the coaxiality to form an insertion unit. (5) Housing sub-assembly 2 for the above insertion unit
The outer housing and the cap 11 are fixed by laser welding. The harness 43 is pulled out upward through the inner cylindrical body 34. (6) After screwing the screw stopper 7 onto the spring guide 41, the high tension cord 6 is connected to the socket portion 7a of the screw stopper 7. The filler 4 is placed in the space around the high tension cord 6 and the harness 43.
6 is loaded and the assembly is completed.

The adjustment of the spring force of the valve spring 9 performed in the sixth item of the assembling procedure will be described with reference to the sectional views of FIG. The state before adjustment is shown in FIG. Next, as shown in FIG. 3B, the set screw 8 is rotated by a tool for turning, for example, a driver 57.
The valve spring 9 is rotated to finely adjust the spring force of the valve spring 9 with respect to the valve 10. Driver 5 at this time
The tip portion of 7 has, for example, a-(minus) shape, and engages with the groove portion 8a of the head portion of the set screw 8. Next, Figure (c)
As shown in FIG. 5, the screw stopper 7 is screwed into the spring guide 41 using a turning tool, for example, a screwdriver 58, and the set screw 8 is tightened and fixed. The tip portion of the driver 58 at this time is, for example, a square pin shape, and engages with the socket portion 7 a of the screw stopper 7. After the spring force of the valve spring 9 is adjusted in this way,
The high tension cord 6 is connected to the screw stopper 7.

According to the fuel injection device, the spring force of the valve spring 9 is finely adjusted by rotating the set screw 8, and then the screw stopper 7 is tightened to fix the set screw 8 at the adjustment position. As a result, the proper shutoff property of the valve 10 can be ensured. Therefore, it is possible to prevent fuel dripping that occurs when the valve 10 is unnecessarily opened under the influence of pressure fluctuations in the combustion chamber of the internal combustion engine due to insufficient spring force, for example.
On the contrary, it is possible to avoid the deterioration of the operation response caused by the insufficient electromagnetic attraction force for opening the valve 10 due to the excessive spring force. Further, by fixing the set screw 8 with the screw stopper 7, unexpected loosening of the set screw 8 due to valve operation is prevented for a long period of time.

[0029]

According to the fuel injection device of the present invention, the valve force can be properly adjusted by finely adjusting the spring force of the valve spring to a proper value and fixing the adjusted state for a long period of time. Can
Therefore, it is possible to prevent fuel dripping and improve the operation response.

[Brief description of drawings]

FIG. 1 is a cross-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 the line AA of FIG.

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 spring force adjustment procedure of a valve spring.

FIG. 8 is a sectional view showing a conventional example.

[Explanation of symbols]

 2 core 3 armature 5 valve seat 5a injection port 7 screw stop 8 set screw 9 valve spring 10 valve 16 bobbin 41 spring guide 42 coil

Claims (1)

[Claims] 1. A tubular core, a bobbin surrounding the outer periphery of the core, a coil wound around the bobbin, a valve having an armature attracted to the core by energization of the coil, and a valve for opening and closing the valve. A fuel injection valve for injecting fuel directly into the combustion chamber of an internal combustion engine, the valve seat having a valve seat having an injection port and a valve spring for urging the valve in a valve closing direction; A fuel injection device having an ignition plug integrally formed with an injection valve, wherein a substantially hollow cylindrical spring guide for accommodating the valve spring is provided in the core, and the spring guide has a spring of the valve spring. A screw for screwing the set screw for adjusting the force and fixing the set screw in the adjustment position. A fuel injection apparatus characterized by marked screw-fit.