JPH0742650A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To provide a fuel injection valve with little knocking wear and sliding wear on the contact face of a fixed core and a movable core at the time of using alcohol fuel with little liquid lubricating action or gas fuel without liquid lubricating action, and reduce the manufacturing cost. CONSTITUTION:At least a movable core 6 and a fixed core 2 are formed of iron group metallic material, and one or both of the lower end 2B of the fixed core 2 and the upper end 6A of the movable core 6 are permeated with chrome so as to form chrome layers on the metal surface thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve used in a fuel injection device, which fuel injection valve is
The fuel is injected based on the injection signal from the CU. The electric signal is converted into the fuel flow rate and the fuel is atomized and injected.

[0002]

2. Description of the Related Art A conventional fuel injection valve is disclosed in Japanese Patent Laid-Open No. 1-1634.
No. 62 publication. According to this, a core of a cylindrical body having a fuel passage formed in the axial direction, an electromagnetic coil wound around the core, a housing accommodating the electromagnetic coil and the core, and an injection hole formed at one end thereof. A valve body having a fuel passage axially formed therein, the other end of which is adjacent to the core and housed in the housing, and a fuel passage of the valve body extending from the fuel passage to the injection hole. One end faces the valve seat formed on the wall so that it can be seated.
An armature facing the core is provided at the other end, and a needle valve slidably disposed in the fuel passage of the valve body and a locking portion provided on the needle valve are provided with a predetermined gap in the axial direction. A fuel injection valve provided with a stopper that faces each other and is fixed to the housing, and that restricts a movement of the needle valve in a direction away from the valve seat to a predetermined distance, at least one of a valve body, a needle valve, and a stopper. A fuel injection valve is shown, one of which is formed of a damping material whose surface is hardened. Then, when the electromagnetic coil is energized, the needle valve is attracted toward the core side against the spring force of the spring, and the movement toward the core side is restricted while the needle valve is in contact with the stopper, and the valve body is closed. Open the seat to the maximum.

[0003]

According to such a conventional fuel injection valve, the opening of the valve seat is determined when the needle valve is in contact with the stopper. For this purpose, a stopper is specially prepared, It is necessary to assemble the stopper corresponding to the needle valve. An armature is prepared and fixed to the end (upper end) on the core side of the needle valve. According to the above, it is necessary to prepare a part different from the stopper and the armature, and it requires an assembling work for attachment, so that an inexpensive fuel injection valve cannot be provided.

On the other hand, from the viewpoint of reducing the number of parts and the number of assembling steps, it is considered that the stopper is abolished and the armature directly contacts the lower end of the core. Not a thing. Particularly in recent years, purification of exhaust gas is more desired, and becomes a problem when alcohol fuel or gas fuel such as natural gas is used in place of gasoline fuel. In other words, when alcohol fuel is used, the viscosity of the fuel is greatly reduced compared to gasoline fuel, so the liquid lubricity is reduced, causing wear and tear, and when natural gas is used, liquid lubrication is not performed at all. Since it does not come off, wear due to wear occurs.

The present invention has been made in view of the above problems, and it is an object of the present invention to use a fuel having a small liquid lubrication effect or a fuel having no liquid lubrication effect at a low manufacturing cost. It is to provide an inexpensive fuel injection valve.

[0006]

In order to achieve the above-mentioned object, a fuel injection valve according to the present invention comprises a cylindrical housing and an inner hole which is disposed in the housing and penetrates in the axial direction in the center thereof. , A coil bobbin around which an electromagnetic coil is wound, a fixed core that is disposed in the inner hole of the coil bobbin, has a through hole in the axial direction, and is magnetically coupled to the housing, and a fixed core. A movable core that is arranged opposite to each other via a spring and has a valve portion at its tip, a valve seat that is opened and closed by the valve portion of the movable core, and a fuel injection hole that is connected to the valve seat and opens outward. And a valve seat forming member attached to the front end of the housing, and restricts the opening side movement stroke of the movable core by bringing the upper end of the movable core into contact with the lower end of the fixed core when the electromagnetic coil is energized. Along with movable And A stationary core formed by an iron-based metallic material, in which impregnated with chromium and at least the movable core and the fixed core within either or both of the lower end of the upper end and the fixed core abutting the movable core.

By forming the chromium layers on the surfaces of the upper end of the movable core and the lower end of the fixed core made of an iron-based metal material, a high surface hardness can be obtained and the surface finish thereof can be improved, so that the durability is improved. Achieves improved wear resistance and wear resistance of those contact surfaces even when using fuel that has poor liquid lubricity or fuel that is not liquid lubricated, because it has reduced frictional resistance it can.
Further, the conventional stopper and armature can be eliminated, and the manufacturing cost can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fuel injection valve according to the present invention will be described with reference to FIG. Reference numeral 1 denotes a bottomed cylindrical housing made of an iron-based metal material and having an opening at the bottom, and a fixed core 2 having a through hole 2A is integrally formed at the center of the housing. In this example, the through hole 2A penetrates downward from above, and the fuel flows in through the through hole 2A above. Reference numeral 3 is a coil bobbin made of a non-magnetic material and having an inner hole 3A penetrating the center thereof, and an electromagnetic coil 4 is wound around the outer circumference. The coil bobbin 3 is inside the housing 1 and the inner hole 3A is inserted into the outer periphery of the fixed core 2. Reference numeral 5 denotes a valve seat forming member fixedly arranged in the opening of the housing 1. The valve seat forming member 5 has a valve seat 5A and a fuel injection hole 5B opening outward from the valve seat 5A. What is done, SUS
It is formed of an iron-based metal material such as 440C. A movable core 6 is arranged between the valve seat 5A of the valve seat forming body 5 and the lower end 2B of the fixed core 2 so that the movable core 6 is allowed to move in the axial direction therebetween. A valve portion 7 that contacts the valve seat 5A is formed at the tip, and the valve portion 7 is elastically biased by the spring 8 together with the movable core 6 by the spring 8 to close the valve seat 5A. Valve seat 5 of movable core 6
The moving stroke on the side of opening A is the upper end 6 of the movable core 6.
A is regulated by abutting on the lower end 2B of the fixed core 2. The movable core 6 including the valve portion 7 is made of an iron-based metal material such as permalloy or KM35.
Reference numeral 9 is a magnetic pole disk which is disposed between the lower collar portion of the coil bobbin 3 and the valve seat forming body 5 and which is magnetically coupled to the housing 1.

When the electromagnetic coil 4 is not energized, the valve portion 7 closes the valve seat 5A by the elastic force of the spring 8, and when the electromagnetic coil 4 is energized, the movable core 6 is closed.
Moves upward against the elastic force of the spring 8 and moves until the upper end 6A of the movable core 6 abuts the lower end 2B of the fixed core 2 so that the valve portion 7 opens the valve seat 5A and thus the through hole 2A. The fuel supplied inside is injected and supplied from the valve seat 5A toward the engine through the fuel injection hole 5B.

The fixed core 2 made of a ferrous metal material
Lower end 2B of the upper end 6 of the movable core 6 made of an iron-based metal material
One or both of A are permeated with chromium to form a chromium layer on the metal surface thereof. According to the above, it is possible to obtain a surface hardness of Hv hardness of about 1400 which cannot be obtained by conventional nitriding, carburizing or quenching on the surface of the lower end 2A of the fixed core 2 or the upper end 6A of the movable core 6. Since the chromium layer is formed on the surface of the lower end 2A of the fixed core 2 or the upper end 6A of the movable core 6 as described above, a smooth high hardness surface is obtained, and thus the lower end 2A of the fixed core 2 and the movable core It is possible to remarkably reduce the wear and sliding wear of the upper end 6A of 6,
In particular, even when alcohol or gas is used as the fuel and the fuel is not (or hardly) not subjected to the liquid lubrication, the wear of the fuel can be suppressed very effectively.

[0011]

As described above, according to the fuel injection valve of the present invention, at least the movable core and the fixed core are made of an iron-based metal material, and one or both of the lower end of the fixed core and the upper end of the movable core are formed. Since the surface of the lower end of the fixed core and the upper end of the movable core can be made into a smooth high hardness surface by infiltrating chromium and forming a chromium layer on the metal surface, gas fuel with no liquid lubricity Alternatively, it is possible to greatly reduce the wear and sliding wear in a fuel injection valve using an alcohol fuel having a low liquid lubricity, and the effect is extremely great. Moreover, since the moving stroke of the movable core is regulated by directly contacting the upper end of the movable core with the lower end of the fixed core, a stopper and an armature are not required, and the number of parts and the number of assembling steps can be reduced. The reduction was 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.

[Explanation of symbols]

 1 Housing 2 Fixed core 2B Lower end of fixed core 6 Movable core 6A Upper end of movable core

Claims (1)

[Claims] 1. A coil bobbin having a cylindrical housing, an inner hole arranged in the housing and penetrating in the axial direction in the center thereof, and an electromagnetic coil wound around the outer periphery, and an inner hole of the coil bobbin. A fixed core that is disposed and has a through hole formed in the axial direction thereof and that is magnetically coupled to the housing; and a movable core that is disposed opposite to the fixed core via a spring and that has a valve portion at its tip. A valve seat forming member that is attached to the front end of the housing and that includes a valve seat that is opened and closed by the valve portion of the movable core, and a fuel injection hole that is connected to the valve seat and opens outward When the electromagnetic coil is energized, the upper end of the movable core is brought into contact with the lower end of the fixed core to control the open side movement stroke of the movable core, and the movable core and the fixed core are formed of an iron-based metal material, and at least Movable core A fuel injection valve in which chrome is infiltrated into one or both of the upper end of the movable core and the lower end of the fixed core with which the fixed core abuts.