JPH0579425A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To provide a fuel injection valve which has a movable iron core with excellent magnetic dymanic characteristic by determining an axial length between a lower engagement stepped portion for holding a valve seat body through an adjusting shim and a lower end of a fixed iron core easily and accurately. CONSTITUTION:A fixed iron core 1 is made of tube-like magnetic material inside which a first through-hole 1A is formed in an axial direction. A non-magnetic tube body 2 is made of tube-like non-magnetic material inside which a second trough-hole 2A is formed in an axial direction. A yoke 3 is made of tube-like magnetic material wherein a valve seat body housing hole 3C is opened from a third through-hole formed in an axial direction through an engagement stepped portion 3H arranged perpendicularly to an axial direction of the third through-hole 3A toward an end. A sleeve assembly is formed by airtightly connecting the means 1, 2, and 3 to each other coaxially. An end 1D of the fixed iron core located in the second through-hole 2A of the non- magnetic tube body 2 is processed with the engagement stepped portion 3H of the yoke 3 of the sleeve assembly being a process reference surface. Axial lengths of the engagement stepped portion 3H and the end 1D of the fixed iron core 1 are determined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a housing, a movable iron core which is magnetically attracted to a fixed iron core by a coil arranged in the housing, a valve portion formed at the front end, and a movable iron core at the rear end. The present invention relates to a fuel injection valve having a needle valve integrally fixed and a valve seat body having a valve seat that is continuous with a valve hole in which a valve portion of the needle valve is seated. Used for.

[0002]

2. Description of the Related Art A conventional fuel injection valve is, for example, an actual open sho-51-.
No. 80517. A conventional example will be described with reference to FIG. Reference numeral 60 denotes a cylindrical housing made of a magnetic material. An upper portion of a large diameter hole 60A provided above is opened upward with an upper locking step portion 60B, and a lower portion of a small diameter hole 60C provided below. Is the lower locking step 60
It is opened downward with D.

Reference numeral 61 is a fixed iron core formed of a magnetic material and having a first through hole 61A penetrating the inside thereof along the axial direction, and an annular locking brim portion 61B extending outwardly at an intermediate portion thereof. The fixed iron core 61 is fixed to the housing 60 by arranging the locking flange portion 61B on the upper locking step portion 60B of the housing 60 and then crimping the upper end of the housing 60 inward. It In addition, the coil 6 is provided on the outer periphery of the fixed iron core 61 in the housing 60.
A coil bobbin 63 around which 2 is wound is arranged.

A needle valve guide hole 63A is formed in the axial direction 63 from the upper side to the lower side, and a valve seat 63B formed below the needle valve guide hole 63A has a valve hole 63C.
It is a valve seat body that opens to the outside through.

The valve seat 63 is arranged on the lower locking step portion 60D of the housing 60 via an adjusting shim 64, and is fixed to the housing 60 by caulking the lower end of the housing 60 inward. ..

The needle valve guide hole 63A of the valve seat 63 is provided with a valve portion 66A for opening and closing the valve seat 63B at its tip, and a rear end of the movable iron core 65 arranged to face the lower end 61C of the fixed iron core 61. Needle valve 66 that is press-fitted and fixed in
Are movably arranged.

Reference numeral 67 is a spring provided between the fixed iron core 61 and the movable iron core 65, and the needle valve 66 including the movable iron core 65 is elastically pressed by the spring 67 so that the valve portion 64A has a valve seat 63B. Is forced to close.

When the coil 62 is not energized, the movable iron core 65 including the needle valve 66 is attached to the spring 6
The valve portion 64A is pressed downward by 7 to hold the valve seat 63B in the closed state. In such a state, the adjustment shim 6
A small first gap S1 (for example, 100 microns) is formed between the lower surface 64A of No. 4 and the stopper flange portion 66B formed on the needle valve 66 so as to face the lower surface 64A, while the fixed iron core 61 A small second gap S2 (for example, 150 microns) is formed between the lower end portion 61C and the upper surface 65A of the movable iron core 65 that faces the fixed iron core 61. That is, the second gap S2 is larger than the first gap S1. In this conventional example, the second gap S2 of 50 microns is larger than the first gap S1.

When the coil 62 is energized, the needle valve 6
The movable iron core 65 including 6 moves upwards against the spring force of the spring 67, and the stopper collar 66B is adjusted by the adjustment shim 64.
Of the needle valve 66 is stopped and stopped in a state of being in contact with the lower surface 64A of the valve seat 64B.
Is opened and fuel is injected from the valve hole 63C. At this time,
The lower end portion 61C of the fixed iron core 61 and the upper surface 6 of the movable iron core 65.
A gap of (second gap S2)-(first gap S1) is formed between the gap and 5A. In this conventional example, a gap of 50 microns is formed. This 50 micron gap is coil 6
This is an air gap as a magnet killer for reducing the residual magnetism with respect to the movable iron core 65 when the power is supplied to 2.

In the operation of the fixed iron core 61 and the movable iron core 65, the lower locking step portion 60D of the housing 60,
The distance L from the lower end 61C of the fixed iron core 61 must be controlled and manufactured with extremely high accuracy. That is, the distance L
Is longer than a predetermined value, the upper surface 65A of the movable iron core 65 and the lower end portion 61C of the fixed iron core 61 are separated from each other, and the initial attraction force to the movable iron core 65 decreases when the coil 62 is energized. On the other hand, when the distance L is short, when the coil 62 is energized, the upper surface 65A of the movable iron core 65 has the lower end portion 6 of the fixed iron core 61.
The air gap becomes small when the coil 62 approaches 1C, and when the coil 62 is de-energized and the coil 62 is de-energized, the return characteristic of the movable iron core 65 deteriorates.

Looking at the conventional example, it is difficult to accurately maintain the distance L between the lower locking step portion 60D of the housing 60 and the lower end portion 61C of the fixed iron core 61. The reasons are given below. (1) Lower locking step 6 of the housing 60
0D is processed with the locking step portion 60B above the housing 60 as a reference. This is the housing 60 of the fixed iron core 61.
This is because the mounting is performed on the upper locking step portion 60B. At this time, since the upper locking step portion 60B and the lower locking step portion 60D are relatively distant from each other, it is difficult to obtain a squareness, and the upper locking step portion 60B and the lower locking step portion 60D are not easily formed. It is difficult to maintain the accuracy of the distance P. (2) Since the fixed iron core 61 is positioned by positioning the locking brim portion 61B on the locking step portion 60B above the housing 60, the lower end portion 61C of the fixed iron core 61 is based on the locking brim portion 61B. Is processed. At this time, the lower surface 61D of the locking collar 61B
Since the distance R between the fixed core 61 and the lower end 61C of the fixed iron core 61 is relatively large and it is necessary to maintain a right angle with respect to the lower surface 61D of the locking collar 61B, this distance R
It is difficult to maintain the accuracy of. (3) Since the two parts of the housing 60 and the fixed iron core 61 are assembled, they are affected by an assembly error.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and includes a lower engaging step portion for holding a valve seat body through an adjusting shim and a lower end portion of a fixed iron core. It is an object of the present invention to provide a fuel injection valve in which the axial length between the two can be manufactured very easily and accurately, and the movable iron core has excellent magnetic dynamic characteristics.

[0013]

According to the present invention, in order to achieve the above-mentioned object, a fixed iron core made of a tubular magnetic material having a first through hole formed therein along the axial direction, and an internal portion A non-magnetic tubular body made of a tubular non-magnetic material in which a second through hole is formed along the axial direction, and a third through hole formed in the axial direction from the third through hole in the axial direction of the third through hole. A sleeve assembly is formed by mechanically and airtightly joining a tubular yoke made of a magnetic material having a valve seat housing hole opening toward the end through a locking step portion orthogonal to At the same time, the end of the fixed core located in the second through hole of the non-magnetic tube is machined using the engagement step of the yoke of the sleeve assembly as the processing reference surface, and the engagement step and the end of the fixed core are processed. And a length in the axial direction of and is formed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fuel injection valve according to the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view showing an embodiment of the fuel injection valve according to the present invention, and FIG. 2 is a vertical sectional view of the sleeve assembly in FIG. In the explanation,
The bottom, left, and right are as shown in the figure and are not limited to these.

Reference numeral A denotes a sleeve assembly arranged at the center of the fuel injection valve in the axial direction thereof.
And a non-magnetic tube body 2 and a yoke 3.

The fixed iron core 1 is formed of a tubular magnetic material, and has a first through hole 1A penetrating downward in the axial direction from the upper side to the lower side.
B, and a small diameter portion 1C is concentrically formed at the lower end portion.

The non-magnetic tubular body 2 is made of a tubular non-magnetic material, and has a second through hole 2A formed in the axial center from the upper side to the lower side and extends outward near the lower end. A large diameter hole 2D continuous with the second through hole 2A is opened at the lower end surface 2C of the non-magnetic tubular collar portion 2B.

The yoke 3 is made of a tubular magnetic material, and has a third through hole 3A formed in the axial direction from the upper side to the lower side, and the lower end surface 3B has the third through hole 3A.
A valve seat body accommodating hole 3C having a diameter larger than that of the third through hole 3A is opened. Further, the non-magnetic tube body 2 is provided on the upper end surface 3E of the flange portion 3D of the yoke 3 which is located at the upper end of the yoke 3 and extends outward.
A positioning protrusion 3F that is positioned and inserted in the large-diameter hole 2D is formed to protrude, and the lower end surface 3B of the yoke 3 is further formed.
A thin portion for crimping 3G for folding and crimping is formed on the outer periphery in the vicinity of the valve seat body storage hole 3C and the third through hole 3
A locking step portion 3H is formed at the connecting portion with A.

To form the sleeve assembly A, the second through hole 2A of the non-magnetic tube body 2 is inserted into the outer periphery of the small diameter portion 1C formed at the lower end of the fixed iron core 1 and then the non-magnetic tube body 2 is inserted. The positioning protrusion 3F of the yoke 3 is inserted into the large diameter hole 2D below. According to this, the fixed iron core 1, the non-magnetic tube body 2, and the yoke 3 are positioned and controlled concentrically (inward and outward). (First through hole 1A, second through hole 2A, third through hole 3
A and the valve seat body housing hole 3C are arranged at the same axis. )

Next, the abutting portion B between the fixed iron core 1 and the non-magnetic tubular body 2 and the abutting portion C between the non-magnetic tubular body 2 and the yoke 3 are joined by brazing, for example. The state of this sleeve assembly A is well shown in FIG.

According to this, the contact portions B and C are mechanically joined to each other and the contact portions are kept airtight. That is, the first through hole 1A, the second through hole 2A, the third through hole 3
A, the valve seat body accommodating holes 3C are mechanically joined to each other with their respective axes being the same axis and forming a single passage, and this passage is kept airtight to the outside of the sleeve assembly A. It

Then, the sleeve assembly A is processed as follows. That is, the locking step portion 3 of the yoke 3
The second through hole 2 of the non-magnetic tube body 2 with H as the machining reference plane XX
The end portion 1D of the fixed iron core 1 protruding into A is processed to form the axial length L of the locking step portion 3H and the end portion 1D of the fixed iron core 1. In this processing, the locking stepped portion 3H of the yoke 3 may be processed once and the processed surface may be used as the processing reference plane XX.

It is also effective to machine the third through hole 3A of the yoke 3 and the second through hole 2A of the non-magnetic tube body 2 concentrically with the valve seat housing hole 3C of the yoke 3 as a processing reference surface. .. This hole processing can be performed simultaneously with the processing of the axial length L. These are shown in FIG.

Then, the fuel injection valve is assembled as follows. A coil bobbin 5 around which the coil 4 is wound is arranged around the sleeve assembly A, and a housing 6 is arranged around the coil bobbin 5. In this state, the lower thin portion of the housing 6 is caulked inward toward the collar portion 3D of the yoke 3 to form the housing 6 and the sleeve assembly A.
And the coil 4 wound around the coil bobbin 5 can be housed in the space between the inner circumference of the housing 6 and the outer circumference of the sleeve assembly A.

Next, a movable iron core 9 integrally fixed with a needle valve 8 having a valve portion 8A formed at the tip from the opening of the lower end surface 3B of the yoke 3 of the sleeve assembly A, the movable iron core 9 and the needle valve 8. The adjustment shim 10 arranged between the stopper collar 8B and the stopper shim 8B is inserted upward, and then the needle valve guide hole 11A and the needle valve guide hole 11A for guiding the needle valve 8 movably in the axial direction are formed. The valve seat body 11 having a valve seat 11B located at the lower end and controlled to open / close by the valve part 8A of the needle valve 8 and a valve hole 11C opening further downward from the valve seat 11B is a lower end surface of the yoke 3. 3B
It is inserted and arranged in the valve seat body housing hole 3C from the opening.

According to this, the upper end 9A of the movable iron core 9 is arranged to face the end 1A of the fixed iron core 1 via the spring 12, and the valve portion 8A of the needle valve 8 is arranged to face the valve seat 11B. On the other hand, the adjusting shim 10 is arranged between the locking step portion 3H of the yoke 3 and the upper end 11D of the valve seat body 11.
In this state, the thin caulking portion 3G of the yoke 3 is caulked inward toward the valve seat body 11. Thus, the valve seat 11 can be integrally fixed to the yoke 3 of the sleeve assembly A, and the movable iron core 9 including the needle valve 8 is allowed to reciprocate in the axial direction.

When the coil 4 is not supplied with electric current, the movable iron core 9 is set to a position separated from the fixed iron core 1 by the spring 12, so that the valve portion 8A of the needle valve 8 has a valve seat. 11B is held in a closed state, the pressurized fuel supplied from the connector pipe 1B reaches the valve seat 11B through the through holes in the sleeve assembly A and the needle valve accommodating hole 11A. It is never injected from 11C.

On the other hand, when current is supplied to the coil 4, the fixed iron core 1 is magnetized and an electromagnetic force is generated so that the movable iron core 9 resists the spring force of the spring 12 and is fixed.
Suction to the side and move. According to this, the needle valve 8 integrated with the movable iron core 9 moves upward, and the needle valve 8
Valve portion 8A opens the valve seat 11B, and the valve hole 11C
More fuel is injected.

Thus, according to the present invention, the locking step portion 3
The length L in the axial direction up to the end 1D of the fixed iron core 1 is machined with H as a machining reference plane XX, and in a single assembly state, the machining length is in a sufficiently short range. Since it was processed, the squareness and its length could be processed extremely accurately and easily, and the fact that the axial length L could be accurately formed in this way means that the movable part including the needle valve is movable. The initial attraction force to the iron core 9 and the return characteristic of the movable iron core 9 when the current to the coil is stopped due to the energized state to the coil can be performed accurately and stably. It was possible to provide a fuel injection valve having excellent magnetic dynamic characteristics.

Further, the valve seat housing hole 3C of the yoke 3, the third through hole 3A of the yoke 3 and the second through hole 2A of the non-magnetic tube body 2 are
Since the valve seat body accommodating hole 3C is machined as the machining reference surface, the machining is performed in a single assembly state, so that the concentric machining is performed with extremely high accuracy. The movable iron core 9 and the needle valve 8 The axial direction can be made extremely smooth, and the resistance to the magnetic force and the spring force of the spring can be kept constant, which also improves the dynamic characteristics of the fuel injection valve.

[0031]

According to the present invention, the housing, the movable iron core magnetically attracted to the fixed iron core by the coil disposed in the housing, the valve portion formed at the front end, and the rear end integrated with the movable iron core. In a fuel injection valve having a fixedly fixed needle valve and a valve seat body having a valve seat connected to a valve hole in which a valve portion of the needle valve is seated, a first through hole is formed in the interior along an axial direction. A fixed iron core made of a tubular magnetic material, a non-magnetic tubular body made of a tubular non-magnetic material having a second through hole formed therein along the axial direction, and The same axis as the yoke made of a tubular magnetic material in which the valve seat accommodating hole is opened from the provided third through hole to the end through the locking step portion orthogonal to the axial direction of the third through hole. The sleeve assembly is made by mechanically and airtightly joining to the sleeve assembly. The end of the fixed iron core located in the second through hole of the non-magnetic pipe is machined using the engagement step of the yoke of the assembly as the processing reference surface, and the shaft of the engagement step and the end of the fixed iron core is processed. Since the axial length is formed, the axial length can be obtained extremely accurately and at low cost, and the dynamic characteristics of the fuel injection valve can be remarkably improved and the performance can be stabilized.

Further, when the axial length of the locking step portion and the end portion of the fixed iron core is machined, the third seat hole of the yoke and the non-magnetic tube body are machined with the valve seat body accommodating hole of the yoke as a machining reference plane. By concentrically machining the second through hole of, the movable iron core and the needle valve can be movably held in the hole in the concentric state, and the operation of the movable iron core and the needle valve is excellent and stable. As a result, the same effects as the above effects could be achieved.

[Brief description of drawings]

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

FIG. 2 is a vertical cross-sectional view showing the sleeve assembly of FIG.

FIG. 3 is a vertical sectional view showing a conventional fuel injection valve.

[Explanation of symbols]

 1 Fixed Iron Core 1A 1st Through Hole 1D End 2 Non-Magnetic Tubular Body 2A 2nd Through Hole 3 Yoke 3A 3rd Through Hole 3C Valve Seat Housing Hole 3H Locking Step 4 Coil 8 Needle Valve 9 Movable Iron Core 10 Adjustment Shim A sleeve assembly

Claims (2)

[Claims] 1. A housing, a movable iron core magnetically attracted to a fixed iron core by a coil arranged in the housing, a valve portion formed at a front end, and a rear end integrally fixed to the movable iron core. In a fuel injection valve having a needle valve and a valve seat body having a valve seat that is continuous with a valve hole in which the valve portion of the needle valve is seated, a first through hole 1A is bored in the inside along the axial direction. A fixed iron core 1 made of a tubular magnetic material, a non-magnetic tubular body 2 made of a tubular non-magnetic material in which a second through hole 2A is bored along the axial direction, and a bore provided in the axial direction. The valve seat housing hole 3C from the formed third through hole 3A toward the end through the locking step portion 3H orthogonal to the axial direction of the third through hole 3A.
The sleeve assembly A is formed by mechanically and airtightly joining a tubular yoke 3 made of a magnetic material, which is open, on the same axis to form a sleeve assembly A.
The end portion 1D of the fixed iron core 1 located in the second through hole 2A of the non-magnetic tube body 2 is processed by using the locking stepped portion 3H of the yoke 3 as the processing reference plane XX, and the locking stepped portion 3H is formed. Fixed core 1 end 1
A fuel injection valve having an axial length L with D. 2. When the axial length L of the locking step 3H and the end 1D of the fixed iron core 1 is machined, the valve seat housing hole 3C of the yoke 3 is used as a machining reference plane for the yoke 3. The fuel injection valve according to claim 1, wherein the third through hole 3A and the second through hole 2A of the non-magnetic tube body 2 are concentrically processed.