JP2002031009A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device capable of reducing a production cost and reducing an eddy current occurred in a stator. SOLUTION: A sucked part 25d sucked to the stator 22 is formed of a soft magnetic material such as a ferrite based stainless steel, and the stator side end face of the sucked part 25d is divided by eddy current interrupting parts 25h and 25i formed of a non-magnetic material such as a martensite based stainless steel to prevent an eddy current from occurring at the stator side end face of the sucked part 25d. In order to assure an air gap between the stator 22 and an armature 25, an abut-on part 25g is formed of a non-magnetic material generally higher in toughness than the magnetic material. The sucked part 25d eddy current interrupting parts 25h and 25i, and abut-on part-25g are formed integral with each other by a metal injection molding to reduce a production cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fuel injection device.

[0002]

2. Description of the Related Art Conventionally, there has been known a fuel injection device in which an armature is sucked by a stator and a valve member which moves together with the armature is reciprocated. In such a fuel injection device, in order to prevent the valve closing response characteristic of the valve member from deteriorating due to the residual magnetism of the stator, a protrusion is provided on the stator or the armature, so that when the armature is sucked into the stator, the stator A predetermined air gap is secured between the suction surface of the armature and the suction surface of the armature.

[0003] Since such a protruding portion collides with the armature or the stator every time the valve member is fully lifted, it is generally formed of a non-magnetic material having higher toughness than a magnetic material. For example, such a protrusion has been formed by a chromium thin film formed by plating on a part of the stator facing surface of the armature.

[0004]

However, when the projecting portion is formed by plating, the magnetic characteristics fluctuate due to variations in the thickness of the thin film formed by plating, which makes it difficult to adjust the fuel injection characteristics. There was a problem. Further, when the protruding portion is formed by plating, there is a problem that the manufacturing cost is increased due to an increase in the number of steps. In addition, since the sucked portion of the armature is generally formed in a tubular shape, eddy currents generated on the stator-facing surface of the annularly formed armature have been a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and reduces the manufacturing cost.
An object is to provide a fuel injection device that reduces eddy current generated in a stator.

[0006]

According to a first aspect of the present invention, a portion to be attracted to a stator is formed of a magnetic material, and an end face of the portion to be attracted to a stator is formed of a non-magnetic material. The eddy current cut-off portion made of the eddy current prevents the eddy current from being generated at the end face of the attracted portion on the stator side. In addition, in order to secure an air gap between the stator and the armature, the abutting portion is formed of a nonmagnetic material that is generally higher in toughness than a magnetic material. Then, the suctioned portion, the eddy current interrupting portion and the contact portion are formed by metal injection molding (MIM: Metal Injection Mol).
Since they are integrally formed by ding, the manufacturing cost can be reduced.

According to the fuel injection device of the second aspect of the present invention, the sucked portion is formed in a cylindrical shape, and the eddy current interrupting portion is buried in the stator side wall portion of the sucked portion in the radial direction. The generation of an eddy current on the surface of the portion to be attracted formed on the surface facing the stator can be prevented. According to the fuel injection device of the third aspect of the present invention, since the eddy current interrupting portion and the contact portion are continuous elements made of a non-magnetic material, metal injection molding is easy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; (First Embodiment) FIG. 1 shows a fuel injection device 1 according to a first embodiment of the present invention. A valve body 29, a valve member 27, an armature 25, a spring 24, a stator 22, an adjusting pipe 21, and a filter 11 are provided in the cylindrical member 14.
Is housed.

[0008] The cylindrical member 14 is a pipe material comprising a magnetic portion and a non-magnetic portion, and is formed of, for example, a composite magnetic material.
By heating a part of the cylindrical member 14 to demagnetize it, a magnetic cylinder portion 14c, a nonmagnetic cylinder portion 14b, and a magnetic cylinder portion 14a are formed in this order from the fuel injection side shown in the lower part of FIG.
An armature 25 is housed near the boundary between the non-magnetic cylindrical portion 14b and the magnetic cylindrical portion 14c of the cylindrical member 14. A valve body 29 and an injection hole plate 28 are provided on the fuel injection side of the magnetic cylinder portion 14c. A filter 1 for removing foreign matter in fuel at an upper fuel upstream side of the cylindrical member 14 in FIG.
1 is attached.

The stator 22 is a cylindrical body made of a ferromagnetic material such as magnetic stainless steel. A chrome thin film is formed on the armature contact surface of the stator 22 by plating. The adjusting pipe 21 is pressed into the stator 22 and fixed to the inner wall of the stator 22. In another embodiment, the adjusting pipe may be screwed to the stator. The urging force of the spring 24 is adjusted according to the depth of press-fitting of the adjusting pipe.

A spool 30 made of resin is provided on the outer periphery of the cylindrical member 14, and a coil 31 is provided on the outer periphery of the spool 30.
Is wound. The connector portion 1 is protruded from the outer wall of the resin mold 13 formed on the outer periphery of the cylindrical member 14.
The terminal 12 electrically connected to the coil 31 is embedded in the connector section 16.
The terminal 12 is partially covered by a resin rib 17.

The magnetic member 23 covers the outer periphery of the coil 31. The magnetic member 18 is provided on the fuel upstream side of the coil 31 so as to avoid the rib 17 in a fan shape having a central angle of about 250 degrees. The resin mold 15 is formed on the outer periphery of the magnetic members 18 and 23 and is connected to the resin mold 13.

The cylindrical valve body 29 is press-fitted into the cylindrical member 14 and fixed to the inner wall of the cylindrical member 14 by laser welding. On the inner peripheral wall of the valve body 29, a truncated conical inclined surface 29a whose diameter decreases toward the injection hole side, and a cylindrical wall surface 29b formed on the fuel upstream side thereof. This truncated cone inclined surface 29a
The diameter of the valve member is reduced in the fuel injection direction, and the contact portion of the valve member 27 forms a valve seat that can be seated. The internal space of the valve body 29 on the fuel upstream side of the truncated cone inclined surface 29a forms a fuel reservoir described in the claims.

The cup-shaped injection hole plate 28 is provided on the magnetic cylinder 1.
4c, is fixed to the inner wall of the magnetic cylinder portion 14c by laser welding, and is in contact with the fuel injection side end surface of the valve body 29. The injection hole plate 28 is formed in a thin plate shape.
A plurality of injection holes 28a are formed in the center.

The valve member 27 and the armature 25 which reciprocate integrally within the cylindrical member 14 are connected to each other by laser welding. The armature 25 is a cylindrical member formed by MIM from sintered powder of a nonmagnetic material such as martensitic stainless steel and sintered powder of a soft magnetic material such as ferritic stainless steel. 2B and 2C, the cross-sectional area of the portion made of the non-magnetic material is hatched to the right and the cross-sectional area of the portion made of the soft magnetic material is hatched to the right. Note that, in FIG. 2, a portion indicated by hatching that is inclined to the lower right is referred to as a core portion in the following description. As shown in FIG. 2, the suctioned portion 25d on the fuel upstream side of the core portion is formed to have a larger diameter than the cylindrical portion 25c on the fuel downstream side. A flange that is in sliding contact with the inner peripheral wall surface of the member 14 is formed. The core has a vertical hole 25e and a vertical hole 2e.
A vapor passage 25a and a lateral hole 25f are formed to communicate the space 5e with the outer peripheral space of the armature 25. Vertical hole 25
e, the inner peripheral step formed on the wall of the spring seat 25b
Is composed.

The contact portion 25g made of a non-magnetic material such as martensitic stainless steel is provided on the stator facing surface 2 of the core.
5j is formed in a ring shape by projecting 30 μm toward the stator side. An air gap of 30 μm is secured between the stator 22 and the armature 25 by the contact portion 25g.

Eddy current interrupting portions 25i and 25h made of a non-magnetic material such as martensitic stainless steel are buried in the radial direction at 180 ° intervals in the stator facing surface 25j of the core portion. The stator-side exposed surfaces of the eddy current interrupting portions 25i and 25h are formed without a step with respect to the stator facing surface 25j of the core portion. The circumferential width of the eddy current interrupting portions 25i and 25h is 0.2 to 0.5 mm. Eddy current interrupter 25i,
The numerical range of the circumferential width of 25h may be determined based on the lower limit dimension that can be processed and the decrease in the magnetic attraction force due to the increase in the width, and is not necessarily limited to the range of the width. Further, as shown in FIG. 2B, the contact portion 25g and the eddy current interrupting portions 25i and 25h are formed as continuous elements made of a non-magnetic material. In addition, at least one eddy current interrupting portion may be embedded in the stator side of the core portion so as to divide the stator-side end face of the core portion in at least one place.

As shown in FIG. 1, the valve member 27 is inserted into the vertical hole 25e of the armature 25 from the fuel downstream side, and is fixed to the wall surface of the vertical hole 25e by laser welding. The valve member 27 includes a sliding portion 27a and a seat portion 27b,
Since the sliding portion 27a is in sliding contact with the inner peripheral wall 29b of the valve body 29, it is reciprocally supported by the inner peripheral wall 29b of the valve body 29. The flange formed on the fuel upstream side of the armature 25 slides on the inner peripheral wall surface of the cylindrical member 14, and the sliding portion 27a of the valve member 27 slides on the inner peripheral wall surface of the valve body 29. The reciprocating trajectory of the member 27 is determined. A notch is formed in the outer wall of the sliding portion 27a, and the notch is formed by this notch.
A fuel passage is formed between the outer peripheral wall 7a and the inner peripheral wall 29b of the valve body 29. The outer peripheral surface of the seat portion 27b includes a cylindrical wall surface and a truncated cone surface, and the truncated cone surface forms a seat portion that is seated on the truncated cone surface 29a of the valve body 29.

The spring 24 has an armature 2 at one end.
5 abuts against the end face of the adjusting pipe 21, and urges the valve member 27 via the armature 25 to a frustoconical inclined surface 29 a as a valve seat.

The fuel flowing into the cylindrical member 14 through the filter 11 passes through the inner space of the adjusting pipe 21, the inner space of the adjusting pipe 21, the inner space of the stator 22, and the inner space of the armature 25, and accumulates in the fuel through a lateral hole 25f. To the seat portion between the seat 27b of the valve member 27 and the valve seat. Seat 27b
When is seated on the valve seat, the communication between the fuel reservoir and the injection hole 28a is interrupted, and when the seat portion 27b is separated from the valve seat, the communication between the fuel reservoir and the injection hole 28a is opened. The configuration of the fuel injection device 1 has been described above.

Next, the operation of the fuel injection device 1 will be described. When energization of the coil 31 is turned on, the armature 25, the stator 22, the magnetic cylinders 14a and 14c, and the magnetic members 18 and 23 form a magnetic circuit through which a magnetic flux generated during energization of the coil 31 passes. At this time, the stator facing surface 25j of the armature 25 is
Since it is divided by 25i, no eddy current is generated on the stator facing surface 25j of the armature 25.
The valve member 27 is attracted to the stator 22 side against the urging force of the spring 24, whereby fuel is injected from the injection hole 28a when the contact portion is separated from the valve seat. The armature 25 collides with the stator 22 when the valve member 27 is fully lifted. At this time, since the contact portion 25g of the armature 25 contacts the stator 22, the stator facing surface 25j of the core portion does not contact the stator 22, and the distance between the stator facing surface 25j and the end face of the stator is 30 μm.
Air gap is secured. When the power to the coil 31 is turned off, the valve member 27 receives a force in the valve closing direction by the urging force of the spring 24, and the seat portion 27b is seated on the valve seat. This terminates the fuel injection from the injection holes 28a.

According to the fuel injection device 1 of the present embodiment, since no eddy current is generated on the stator facing surface 25j of the armature 25, the responsiveness of the on-off valve operation can be improved. Further, since the contact portion 25g for securing an air gap between the stator 22 and the armature 25 is formed integrally with the core portion by MIM, it is not necessary to form a chrome thin film or the like on the stator facing surface of the armature 25 by plating. In addition, the manufacturing cost can be reduced by simplifying the manufacturing process.

Further, when an air gap is ensured by a chromium thin film formed by plating as in the prior art, it is difficult to reduce the manufacturing tolerance of the film thickness. It has been difficult to adjust the flow rate of the fuel injection device. On the other hand, in the present embodiment, since the contact portion 25g is formed by injection molding, the manufacturing tolerance of the protruding height of the contact portion 25g can be reduced, and the individual difference in magnetic characteristics is small. Adjustment of the flow rate of the device 1 is easy.

[Brief description of the drawings]

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

2A and 2B are diagrams showing an armature of a fuel injection device according to an embodiment of the present invention, wherein FIG. 2A is a plan view, FIG. 2B is a cross-sectional view taken along the line BB of FIG. It is CC sectional view taken on the line of A).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection device 14 Cylindrical member 21 Adjusting pipe 22 Stator 24 Spring 25 Armature 25d Part to be attracted 25f Fuel passage 25g Contact part 25h Eddy current cutoff part 25i Eddy current cutoff part 27 Valve member 27a Sliding part 27b Seat part 28 Injection Hole plate 28a Injection hole 29a Truncated cone inclined surface (valve seat) 29 Valve body 31 Coil

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16K 31/06 385 F16K 31/06 385A H01F 7/16 H01F 7/16 DEFR Term (Reference) 3G066 AA01 AB02 BA19 BA51 BA61 CC06U CC11 CC18 CC20 CC61 CD30 CE23 CE24 CE25 CE26 CE31 3H106 DA07 DA13 DA23 DB02 DB12 DB22 DB32 DC02 DC17 DD03 EE04 EE16 EE34 GA15 GA16 GA19 GA21 GC29 JJ02 JJ05 KK18 5E048 AB01 AD04

Claims (3)

[Claims] A valve body in which a fuel reservoir and a valve seat are formed; and a fuel passage from the fuel reservoir to an injection hole when the valve body is seated on the valve seat, and is separated from the valve seat. A valve member that opens the fuel passage, an armature that moves in the same direction as the movement direction of the valve member, a stator that sucks the armature in a valve opening direction, and a coil that generates an electromagnetic attraction force in the stator. The armature has a attracted portion made of a magnetic material, an eddy current interrupting portion made of a non-magnetic material and dividing at least a stator-side end face of the attracted portion, and a attracted portion made of a non-magnetic material. A fuel injection device, wherein a contact portion protruding from the stator side end surface toward the stator and capable of contacting the stator is integrally formed by metal injection molding. 2. The fuel injection according to claim 1, wherein the suctioned portion is formed in a cylindrical shape, and the eddy current interrupting portion is buried in a radial direction in a stator side wall portion of the suctioned portion. apparatus. 3. The fuel injection device according to claim 1, wherein the eddy current interrupting portion and the contact portion are continuous elements made of a non-magnetic material.