JP2002089399A - Electromagnetic fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic fuel injection valve having stability in valve assembly opening and closing attitude and good responsiveness and capable of lowering of the fuel consumption of an engine. SOLUTION: This electromagnetic fuel injection valve is provided with a valve seat member 3 having a valve seat 8, a valve housing 2 connected to one end of the valve seat member 3 at one end thereof, a fixed core 5 connected to the other end of the valve housing 2, a movable core 12 housed in the valve housing 2 freely to be slid, and a valve assembly V continuously provided to the movable core 12 through a rod part 15 and formed of the valve seat 8 and a cooperating valve part 16. The valve housing 2 is provided with a guide part 4 for supporting the valve assembly V freely to be slid in the axial direction, and the peripheral surface of the valve assembly V brought in contact with the guide part 4 is formed with a high hardness film 14 made of TiN and having Rmax 0.5-1.5 μm of surface roughness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic fuel injection valve mainly used for a fuel supply system of an internal combustion engine, and more particularly, to a valve seat member having a valve seat and one end provided at the other end of the valve seat member. A valve housing connecting the parts, a fixed core connected to the other end of the valve housing, a movable core slidably received in the valve housing so as to face the fixed core, and A valve assembly comprising a valve portion cooperating with the valve seat and connected via a rod portion, and a guide portion for supporting the valve assembly slidably in the axial direction in the valve housing; On the outer peripheral surface of the valve assembly
The present invention relates to a method of forming a high hardness coating for imparting abrasion resistance.

[0002]

2. Description of the Related Art Such an electromagnetic fuel injection valve is already known, for example, as disclosed in Japanese Patent Application Laid-Open No. H11-22585.

[0003]

Conventionally, in such an electromagnetic fuel injection valve, the surface roughness of the high hardness coating formed on the outer peripheral surface of the valve assembly is generally set to Rmax 2 μm or more.

[0004] In recent years, there has been an increasing demand for improved fuel economy of the engine. In order to cope with this, it is necessary to increase the accuracy of the fuel injection amount of the electromagnetic fuel injection valve. May stabilize posture.
In order to stabilize the opening / closing posture of the valve assembly, the dimensional accuracy of the valve assembly and its guide is enhanced to minimize the sliding gap between the two, and the surface roughness of the high hardness coating formed on the valve assembly is reduced. Even if Rmax is 2 μm, the responsiveness of the valve assembly is degraded due to the increase in the sliding resistance, which adversely affects the accuracy of the fuel injection amount and increases power consumption.

The present invention has been made in view of such circumstances, and even if the dimensional accuracy of the valve assembly and its guide portion is increased to minimize the sliding gap between the two, the sliding resistance is increased. Therefore, the opening and closing posture of the valve assembly is stable and excellent in responsiveness, which can contribute to the improvement of fuel efficiency of the engine.
It is an object to provide the electromagnetic fuel injection valve.

[0006]

In order to achieve the above object, the present invention provides a valve seat member having a valve seat, a valve housing having one end connected to the other end of the valve seat member, and a valve housing. A fixed core coupled to the other end of the housing, a movable core slidably housed in the valve housing so as to face the fixed core, and a movable core connected to the movable core via a rod portion; A valve assembly comprising a valve portion cooperating with a valve seat; a guide portion for slidably supporting the valve assembly in an axial direction in a valve housing; and an outer peripheral surface of the valve assembly in contact with the guide portion. In an electromagnetic fuel injector having a high hardness coating for imparting abrasion resistance, the first aspect is that the surface roughness of the high hardness coating is Rmax 0.5 to 1.5 μm.
The feature of.

According to the first feature, by setting the surface roughness of the high hardness coating to Rmax 0.5 to 1.5 μm, the valve assembly and the guide portion thereof are not increased without increasing the sliding resistance. By improving the dimensional accuracy of the valve and minimizing the sliding gap between the two, it is possible to achieve both stable opening and closing posture of the valve assembly and improved responsiveness, contributing to improved fuel economy of the engine. I can do it.

The present invention has a second feature that, in addition to the first feature, the high hardness coating is TiN.

According to the second feature, TiN constituting the high hardness coating has a smaller coefficient of friction than a general hard coating of Cr plating, and effectively increases the sliding resistance of the valve assembly. Can be suppressed.

[0010] In addition to the first or second feature, the present invention further comprises a non-portion wherein the guide portion is fixed to the valve housing adjacent to the fixed core and supports the movable core slidably in the axial direction. A third feature is that the movable core is formed of a magnetic annular spacer and the high hardness coating is formed on an outer peripheral surface of the movable core.

According to the third feature, the axial movement of the end of the heaviest part of the movable core in the valve assembly is supported by the annular spacer, so that the opening and closing posture of the valve assembly can be more stabilized. Can be enhanced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on embodiments of the present invention shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view of an electromagnetic fuel injection valve for an internal combustion engine according to a first embodiment of the present invention, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. FIG. 4 is a graph showing a fuel injection amount change rate comparison test, and FIG. 5 is a sectional view corresponding to FIG. 2, showing a second embodiment of the present invention.

First, a description will be given of a first embodiment of the present invention shown in FIGS.

1 and 2, a casing 1 of an electromagnetic fuel injection valve I for an internal combustion engine is liquid-tightly connected to a cylindrical valve housing 2 (magnetic material) and a front end of the valve housing 2. A cylindrical valve seat member 3 having a bottom and a valve housing 2
And a cylindrical fixed core 5 which is liquid-tightly connected to the rear end with an annular spacer 4 interposed therebetween.

The annular spacer 4 is made of a non-magnetic metal, for example, stainless steel. The valve housing 2 and the fixed core 5 are brought into contact with both ends of the annular spacer 4 and are liquid-tightly welded all around.

A first fitting cylindrical portion 3a and a second fitting cylindrical portion 2a are formed at opposite ends of the valve seat member 3 and the valve housing 2, respectively. Then, the first fitting cylinder 3a is pressed into the second fitting cylinder 2a together with the stopper plate 6, and the stopper plate 6 is sandwiched between the valve housing 2 and the valve seat member 3. Thereafter, laser welding or beam welding is performed over the entire periphery of a corner portion sandwiched between the outer peripheral surface of the first fitting tubular portion 3a and the end face of the second fitting tubular portion 2a, so that the valve housing 2 and the valve seat member 3 are formed. Are connected to each other in a liquid-tight manner.

The valve seat member 3 has a valve hole 7 opened at the front end face thereof, a conical valve seat 8 connected to the inner end of the valve hole 7, and a cylindrical valve connected to a large diameter portion of the valve seat 8. A guide hole 9 is formed, and the guide hole 9 is formed coaxially with the second fitting cylindrical portion 2a.

An injector plate 10 made of a steel plate and having a plurality of fuel injection holes 11 communicating with the valve holes 7 is liquid-tightly welded to the front end face of the valve seat member 3 in a liquid-tight manner.

A movable core 12 facing the front end face of the fixed core 5 is accommodated in the valve housing 2 and the annular spacer 4, and the inner peripheral surface of the annular spacer 4 is, as shown in FIGS. An annular guide surface 13 that protrudes the movable core 12 slidably in the axial direction is protruded. On the outer peripheral surface of the movable core 12 that is in contact with the guide surface 13, a high hardness coating 14 made of TiN is formed to reduce the sliding resistance of the movable core 12 with respect to the guide surface 13. The plasma spraying method is used to form the TiN coating 14, and the surface roughness is Rm.
ax is set to 0.5 to 1.5 μm.

Here, the surface roughness of the high-hardness coating 14 is set to Rm.
The reason for setting the ax to 0.5 to 1.5 μm is that if it is less than 0.5 μm, the production efficiency is undesirably reduced,
If it exceeds m, the effect of reducing the sliding resistance is hardly obtained.

The movable core 12 is integrally provided with a small-diameter rod portion 15 extending from one end surface thereof to the valve seat 8 side, and a spherical valve which can be seated on the valve seat 8 at the tip of the rod portion 15. The part 16 is fixed by welding. Thus, the movable core 12,
The valve assembly V is constituted by the rod portion 15 and the valve portion 16.

The valve portion 16 is supported in the guide hole 9 so as to be slidable in the axial direction.
A plurality of chamfers 17 that allow the fuel to flow through the inside are formed at equal intervals.

The stopper plate 6 is provided with a notch 18 through which the rod 15 penetrates. A stopper flange 19 facing the end face of the stopper plate 6 on the valve seat 8 side is provided at an intermediate portion of the rod 15. Is formed. Between the stopper plate 6 and the stopper flange 19, a gap g corresponding to the valve opening stroke of the valve portion 16 when the valve portion 16 is closed, that is, when the valve portion 16 is seated on the valve seat 8, is provided.

On the other hand, between the fixed core 5 and the movable core 12, even when the valve portion 16 is closed, that is, when the valve portion 16 is seated on the valve seat 8, it is sufficient to avoid contact between the two cores 5, 12. A gap is provided.

The fixed core 5 has a hollow portion 21 communicating with the inside of the valve housing 10 through the through hole 20 of the movable core 12, and the movable core 12 is inserted into the hollow portion 21 in the closing direction of the valve portion 16. That is, a coil-shaped valve spring 22 that urges the valve seat 8 in the seating direction and a pipe-shaped retainer 23 that supports the rear end of the valve spring 22 are housed.

At this time, a positioning recess 24 for receiving the front end of the valve spring 22 is formed on the rear end surface of the movable core 12. The set load of the valve spring 22 is adjusted by the press-fit depth of the retainer 23 into the hollow portion 21.

At the rear end of the fixed core 5, an inlet tube 26 having a fuel inlet 25 communicating with the hollow portion 21 of the fixed core 5 through a pipe-shaped retainer 23 is integrally connected. The fuel filter 35 is mounted.

A coil assembly 28 is fitted around the outer periphery of the annular spacer 4 and the fixed core 5. This coil assembly 28
Is composed of a bobbin 29 fitted on the outer peripheral surface of the annular spacer 4 and the fixed core 5, and a coil 30 wound around the bobbin 29. One end of a coil housing 31 surrounding the coil assembly 28 is a valve. It is connected to the outer peripheral surface of the housing 2 by welding.

Coil housing 31, coil assembly 28
The fixed core 5 is embedded in a cover 32 made of synthetic resin, and a coupler 34 for accommodating a connection terminal 33 connected to the coil 30 is integrally provided at an intermediate portion of the cover 32. .

An annular groove 36 is defined between the front end surface of the cover 32 and a cap 35 made of synthetic resin fitted to the front end of the valve seat member 3. An O-ring 37 closely attached to the outer peripheral surface of the fuel injection valve 2 is attached to an inner peripheral surface of the mounting hole when the electromagnetic fuel injection valve I is mounted in a fuel injection valve mounting hole of an intake manifold (not shown). It comes to be close to.

Next, the operation of the first embodiment will be described.

As shown in FIG. 2, when the coil 30 is demagnetized, the movable core 12 and the valve portion 18 are pressed forward by the urging force of the valve spring 22, and the valve portion 18 is seated on the valve seat 8. . Therefore, the high-pressure fuel supplied into the valve housing 1 through the fuel filter 35 and the inlet cylinder 26 is made to wait in the valve housing 1.

When the coil 30 is excited by energization, the magnetic flux generated by the excitation is fixed core 5, coil housing 3
1, the valve housing 10 and the movable core 12 run sequentially, and the movable core 12 of the valve assembly V is attracted to the fixed core 5 together with the valve portion 18 by the magnetic force, and the valve seat 8 is opened. The high-pressure fuel is supplied to the chamfer 17
Then, the fuel passes through the fuel outlet 13 and is injected from the fuel injection hole 11 toward the intake valve of the engine. At this time, the stopper flange 19 of the valve assembly V comes into contact with the stopper plate 6 fixed to the valve housing 2 so that the valve assembly V
Is defined.

During operation of such an electromagnetic fuel injection valve I,
The opening and closing posture of the valve assembly V is such that both ends are annular spacers 4.
The valve assembly V is supported by the guide surface 13 and the guide hole 9 of the valve seat member 3 so that the valve assembly V is always properly maintained and does not tilt. In addition, the injection characteristics can be stabilized.

Moreover, in order to obtain high stability of the opening / closing posture of the valve assembly V, even if the sliding gap between the annular spacer 4 and the valve assembly V is minimized, it is formed on the outer peripheral surface of the movable core 12.
High hardness coating 14 having a surface roughness Rmax of 0.5 to 1.5 μm
Causes a reduction in sliding resistance of the valve assembly V with respect to the guide surface 13, so that the minimum operating voltage is reduced, and high responsiveness of the valve assembly V can be ensured even when the voltage changes.

Actually, TiN having a surface roughness Rmax of 2 μm
Movable core with high hardness coating, and surface roughness Rmax0.5
When a comparative test was performed with the movable core 12 of the present invention having a TiN high hardness coating 14 of about 1.5 μm, the minimum operating voltage was 9 V in the conventional one, , A significant improvement of 5 V was observed.
Further, as shown in the graph of FIG. 4, the change rate of the fuel injection amount increases rapidly with the increase in the number of opening and closing operations, whereas the change rate of the fuel injection amount of the present invention increases. Was found to be extremely low.

In particular, when the high hardness coating 14 is made of TiN, the friction coefficient of the high hardness coating 14 is smaller than that of the Cr plating high hardness coating, which has been widely used in the past, so that the valve assembly V slides on the guide surface 13. Dynamic resistance can be further reduced.

In the present invention, not only the movable core 12 but also
If the portion is guided by the valve housing 2 or a portion fixed to the valve housing 2, the high-hardness coating 1 is applied anywhere on the valve assembly V.
In particular, if the above-described high hardness coating 14 is formed on the movable core 12, the axial movement of the end of the heaviest part of the movable core 12 in the valve assembly V is circular. Since the support is made by the spacer 4, the opening and closing posture of the valve assembly V can be more stabilized.

As described above, since the opening and closing posture of the valve assembly V can be stabilized and the responsiveness can be improved at the same time, the fuel injection amount can be stabilized for a long time, and the fuel efficiency of the engine can be improved. be able to.

Next, a second embodiment of the present invention shown in FIG. 5 will be described.

In the second embodiment, instead of the stopper plate 6 and the stopper flange 19 in the previous embodiment,
A stopper surface 38 is formed on the annular spacer 4 so as to project radially inward from the inner peripheral surface of the valve housing 2.
An annular shoulder 39 is formed on the outer periphery of the movable core 12 to abut on the stopper surface 38 and define the valve opening limit of the valve portion 16. The movable core 12 has a surface roughness Rmax of 0.5 to 1.5 μm TiN on the annular shoulder 39 in addition to the outer peripheral surface thereof.
The high hardness coating 14 is formed. The other configuration is the same as that of the first embodiment. Therefore, in FIG. 5, portions corresponding to those of the previous embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The present invention is not limited to the above embodiment, and various design changes can be made without departing from the gist of the present invention.

[0044]

As described above, according to the first aspect of the present invention, a valve seat member having a valve seat, a valve housing having one end connected to the other end of the valve seat member, and the valve housing A fixed core coupled to the other end of the valve, a movable core slidably housed in the valve housing so as to face the fixed core, and a valve connected to the movable core via a rod to connect the movable core to the valve core. A valve assembly comprising a valve portion cooperating with a seat, a guide portion for supporting the valve assembly slidably in the axial direction in the valve housing, and an outer peripheral surface of the valve assembly contacting the guide portion;
In an electromagnetic fuel injection valve having a high hardness coating for imparting wear resistance, the surface roughness of the high hardness coating is determined by R
Since the maximum value is 0.5 to 1.5 μm, it is possible to increase the dimensional accuracy of the valve assembly and its guide portion and minimize the sliding gap between the two without increasing the sliding resistance. Long-term stabilization of the three-dimensional opening / closing posture and improvement of responsiveness can be achieved at the same time, which can contribute to improvement of fuel efficiency of the engine.

According to the second feature of the present invention, since the high-hardness coating is made of TiN, an increase in sliding resistance of the valve assembly can be suppressed more effectively.

According to a third aspect of the present invention, the guide portion is fixed to the valve housing adjacent to the fixed core, and the non-magnetic annular spacer supports the movable core slidably in the axial direction. And the high hardness coating is formed on the outer peripheral surface of the movable core, so that the axial movement of the end of the movable core of the heaviest part in the valve assembly is supported by the annular spacer, so that the valve assembly is , The opening and closing posture can be more stabilized.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electromagnetic fuel injection valve for an internal combustion engine according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a graph showing a fuel injection amount change rate comparison test.

FIG. 5 is a sectional view corresponding to FIG. 2, showing a second embodiment of the present invention.

[Explanation of symbols]

 I ......... Electromagnetic fuel injection valve V .... Valve assembly 2 .... Valve housing 3 ..... Valve seat member 4 .... Spacer (guide portion) 5 .. ... fixed core 8 ... valve seat 12 ... movable core 14 ... hard coating 15 ... rod 16 ... valve

Claims (3)

[Claims] 1. A valve seat member (3) having a valve seat (8),
A valve housing (2) having one end coupled to the other end of the valve seat member (3); a fixed core (5) coupled to the other end of the valve housing (2); The movable core (12) is slidably housed in the valve housing (2) so as to face the valve seat (2). A valve assembly (V) comprising a valve portion (16) cooperating with the valve assembly (8), and a guide portion (4) for supporting the valve assembly (V) slidably in the axial direction on the valve housing (2). And a high hardness coating (14) formed on the outer peripheral surface of the valve assembly (V) in contact with the guide portion (4). In the electromagnetic fuel injection valve, the surface roughness of the high hardness coating (14) is reduced. An electromagnetic fuel injection valve having a Rmax of 0.5 to 1.5 μm. 2. The electromagnetic fuel injection valve according to claim 1, wherein said high hardness coating is made of TiN. 3. The electromagnetic fuel injection valve according to claim 1, wherein the guide portion is fixed to a valve housing (2) adjacent to the fixed core (5), and the movable core (1) is fixed to the valve housing (2).
(2) The magnetic core (12) is constituted by a non-magnetic annular spacer (4) which is slidably supported in the axial direction, and the high hardness coating (14) is formed on the outer peripheral surface of the movable core (12). Type fuel injection valve.