JPH0712028A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To use fuel of small liquid lubricating action or fuel of no liquid lubricating action at all by forming a chrome layer in a surface of iron metal material. CONSTITUTION:In a valve element 7, a valve seat 5A is closed by elastic force of a spring 8, and by electifying an electromagnetic coil 4, the valve element 7 is moved upward against elastic force of the spring 8 to open the valve seat 5A, so that fuel supplied into a through hole 2A is supplied toward an engine from the valve seat 5A through a fuel injection hole 5B. By forming a chrome layer in a surface of the valve element 7 or valve seat 5A, a smooth surface of high hardness is obtained, and as a result, hammering wear and sliding wear of the valve element 7 and the valve seat 5A can be remarkably reduced. Accordingly, alcohol or gas is used as fuel, and even in a condition of using fuel where liquid lubrication by fuel is not performed (or not easily performed), wear of these parts can be very effectively suppressed.

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, for example, Japanese Utility Model 4-8.
No. 308 is disclosed. According to this, the fuel injection valve is arranged in a cylindrical housing, a coil bobbin provided inside the housing, and an electromagnetic coil wound around the housing, and an inner hole of the coil bobbin, and is movable by energizing the electromagnetic coil. It consists of a fixed core that magnetically attracts the core and a valve seat forming body that is attached to the tip of the housing and that has a valve seat that is opened and closed by a valve portion that is integrally provided on the movable core. Then, a magnetic circuit is formed by the housing, the fixed core and the movable core, and the magnetic force generated by the magnetic circuit causes the movable core to be attracted to the fixed core against the spring force of the spring, so that the valve portion forms the valve seat forming body. The valve seat is opened and fuel is injected toward the engine. On the other hand, when the power supply to the electromagnetic coil is cut off, the magnetic force disappears,
The valve portion closes the valve seat by the spring force of the spring, so that fuel injection toward the engine is suppressed. The opening and closing of the valve seat by the valve portion is repeatedly performed during the operation of the engine. Here, an iron-based metal material such as SUS440C is used for the movable iron core including the valve portion of the conventional fuel injection valve, and the valve seat forming body including the valve seat is Permalloy, KM3.
It is formed of an iron-based metal material such as No. 5.

[0003]

In recent years, purification of exhaust gas has been more desired, and gas fuel such as alcohol fuel or natural gas is used in place of gasoline fuel. When this alcohol fuel is used, the viscosity of the fuel is greatly reduced compared to gasoline fuel, so the liquid lubricity is reduced, and countermeasures are taken against scab wear between the valve part and the valve seat or sliding wear of the movable core. You need to cheat. Further, when natural gas is used, it is necessary to give sufficient consideration to loosening wear and sliding wear because no lubrication with liquid is performed.

The present invention has been made in view of the above problems.
An object of the invention is to provide a fuel injection valve capable of using a fuel having a small liquid lubrication effect or a fuel having no liquid lubrication effect at all.

[0005]

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 housing provided with 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, and a fuel injection hole that is open outward toward the valve seat. In a fuel injection valve having a valve seat forming body attached to the tip of the valve, at least the valve portion of the movable core and the valve seat forming body are formed of an iron-based metal material, and one of the valve portion and the valve seat forming body is formed. Or it is made by infiltrating chromium into both. .

[0006]

By forming the chromium layer on the surface of the iron-based metal material, it is possible to obtain a high surface hardness and improve its surface finish, thereby improving wear resistance and reducing frictional resistance. Even if the fuel having poor liquid lubricity or the fuel not subjected to liquid lubrication is used, the wearability of the movable core including the valve portion and the valve seat can be improved.

[0007]

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 is a valve seat forming body fixedly arranged in the opening of the housing 1. The valve seat forming body 5 is formed with 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 facing 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. And this valve part 7
The movable core 6 including is made of an iron-based metal material such as Permalloy or KM35.

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 valve portion 7 is elastic force of the spring 8. Against this, the valve seat 5A is opened to open, so that the fuel supplied into the through hole 2A is injected and supplied from the valve seat 5A toward the engine through the fuel injection hole 5B.

Further, in the fuel injection valve according to the present invention, chromium is infiltrated into either or both of the valve seat 5A made of an iron-based metal material and the valve portion 7 made of an iron-based metal material, and both of them are introduced. A chromium layer is formed on the metal surface. According to the above, a surface hardness of HV hardness of about 1400, which cannot be obtained by conventional nitriding, carburizing, and quenching, can be obtained on the surface of the valve portion 7 or the valve seat 5A. According to the formation of the chrome layer on the surface of the valve portion 7 or the valve seat 5A in this manner, a smooth and hard surface can be obtained, and thus the valve portion 7 and the valve seat 5A can be worn against sliding and sliding wear. It is possible to significantly reduce the wear of alcohol or gas as a fuel, and even if the fuel is not liquid lubricated by the fuel (or is difficult to perform), the wear of those fuels can be suppressed very effectively. It is a thing.

[0010]

As described above, according to the fuel injection valve of the present invention, at least the valve portion of the movable core and the valve seat forming body are made of the ferrous metal material, and one of the valve portion and the valve seat forming body is formed. Or, by infiltrating chrome into both of them and forming a chrome layer on their metal surface, the surface of the valve part or the valve seat forming body (valve seat) can be made to have a smooth high hardness surface. It is possible to greatly reduce the wear and sliding wear of a fuel injection valve using a non-compliant gas fuel or an alcohol fuel having a low liquid lubricity, and the effect is extremely great.

[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]

 5 valve seat forming body 5A valve seat 6 movable core 7 valve part

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. In a fuel injection valve having a valve seat that is opened and closed by a valve portion and a fuel injection hole that is connected to the valve seat and opens outward, and is attached to the front end of the housing, A fuel injection valve in which at least the valve portion 7 of the movable core and the valve seat forming body 5 are made of an iron-based metal material, and chromium is infiltrated into one or both of the valve portion 7 and the valve seat forming body 5.