TECHNICAL FIELD

The present invention relates to an electromagnetic valve, more particularly to an electromagnetic valve used in a fuel system in which a member constituting a magnetic circuit is made of a soft magnetic material in an electromagnetic drive unit.

BACKGROUND ART

An electromagnetically driven fuel injection valve is used for injecting fuel into a combustion chamber of a gasoline engine. In an electromagnetic drive unit of this kind of fuel injection valve, electromagnetic stainless steel exhibiting high corrosion resistance and soft magnetism has been widely used as a material used for a member constituting a magnetic circuit, such as a core or a housing. A fuel injection valve using such electromagnetic stainless steel is disclosed in, for example, Patent Literature 1.

CITATION LIST

Patent Literature

Patent Literature 1: JP-A-H01-290749

SUMMARY OF INVENTION

Technical Problem

In recent years, in the fuel injection valve of a gasoline engine, high pressure injection or multistage injection is being advanced in view of reduction in a CO2emission amount, energy saving, improvement in fuel consumption, and the like. In order to achieve high pressure injection in the electromagnetic valve, a high magnetic flux density is required in the material constituting the magnetic circuit. In order to perform high pressure injection, a large magnetic attraction force is necessary to control opening and closing of the electromagnetic valve. As the material constituting the magnetic circuit has high saturation magnetic flux density, it is possible to follow operation of the electromagnetic drive unit in a high magnetic field and generate a large magnetic attraction force. In order to efficiently perform multistage injection, high responsiveness is required for the electromagnetic drive unit. As the material constituting the magnetic circuit has high electrical resistance, the responsiveness of the electromagnetic drive unit can be improved. In this way, the material constituting the magnetic circuit of the electromagnetic valve used in a fuel system is required to have high saturation magnetic flux density and electrical resistance in addition to high corrosion resistance.

It is desired that the saturation magnetic flux density has a high value of, for example, 1.8 T or higher. However, it is difficult to achieve such a high saturation magnetic flux density by using such a conventional electromagnetic stainless steel as disclosed in Patent Literature 1.

A problem to be solved by the present invention is to provide an electromagnetic valve used in a fuel system where a magnetic circuit made of an alloy material having excellent corrosion resistance, high saturation magnetic flux density, and high electrical resistance is provided in an electromagnetic drive unit.

Solution to Problem

In order to solve the above problem, the electromagnetic valve according to the present invention is an electromagnetic valve used in a fuel system, containing a member constituting a magnetic circuit in an electromagnetic drive unit, in which at least a part of the member is made of an alloy material containing, in mass %, 0.15%≤Ni≤0.45%, 0.65%≤Al≤1.0%, 9.2%≤Cr≤10.3%, and 0.90%≤Mo≤1.6% with the balance being Fe and inevitable impurities.

Here, the electromagnetic valve is preferably a fuel injection valve.

The alloy material preferably further contains 0.05%≤Pb≤0.15% in mass %.

The alloy material preferably has a structure of an α phase single phase.

Advantageous Effects of Invention

In the electromagnetic valve of the present invention, a magnetic circuit of an electromagnetic drive unit is made of an alloy material having a component composition as described above. The alloy material has high saturation magnetic flux density and electrical resistance in addition to high corrosion resistance owing to an effect of the component composition. As a result, in the electromagnetic valve, high pressure injection owing to a high magnetic attraction force and multistage injection owing to improvement in responsiveness are facilitated.

Here, in the case where the electromagnetic valve is a fuel injection valve, effects of high corrosion resistance, high pressure injection owing to a high magnetic attraction force, and multistage injection owing to improvement in responsiveness can be particularly effectively utilized.

In the case where the alloy material further contains 0.05%≤Pb≤0.15% in mass %, machinability of the alloy material is improved, and the member constituting the magnetic circuit is easily processed in the electromagnetic valve.

In the case where the structure of the alloy material is an α phase single phase, a low coercive force is secured and excellent soft magnetic characteristics are easily obtained in the alloy material. As a result, the responsiveness of the electromagnetic valve is easily improved.

