Ferritic Stainless Steel Solenoid Valve Pole Core Hardening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solenoid valves for high-pressure fuel pumps face challenges in wear resistance and positioning accuracy due to the mechanical softness of materials used for pole cores, which affects their durability and magnetic properties.
Innovation Solution
A solenoid valve design featuring a pole core made of ferritic stainless steel with a hard chrome-plated armature stop, where only the end region is cold-formed for increased hardness and precision, allowing for improved fatigue strength and reduced magnetic sticking, while maintaining soft-magnetic properties in the rest of the core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pole core is made of soft-annealed ferritic stainless steel to achieve good soft-magnetic properties, then the magnetic performance is improved, but the mechanical hardness and wear resistance deteriorate
Solution Approach 1:
The invention applies different material properties to different regions of the pole core. The basic structure is made of soft-annealed ferritic stainless steel for good magnetic properties, while the end face forming the stop is locally cold-formed to increase hardness. This local differentiation resolves the contradiction between overall magnetic performance and localized wear resistance.
Solution Approach 2:
The invention creates a composite structure where the pole core combines soft-annealed ferritic stainless steel material with a cold-formed hardened surface layer. This composite approach allows the bulk material to provide magnetic properties while the surface layer provides wear resistance, resolving the contradiction between these two requirements.
2Strength
If cold plastic working is applied to the pole core to increase hardness, then the wear resistance is improved, but the magnetic properties deteriorate
Solution Approach 1:
The cold plastic working is applied only to the end face of the pole core that forms the stop, not to the entire pole core. This localized treatment increases hardness where needed for wear resistance while leaving the main body of the pole core with its soft-magnetic properties intact, thus resolving the contradiction.
3Strength
If the armature stop is plated with hard chrome layer to increase hardness and reduce magnetic sticking, then the wear resistance is improved, but the manufacturing complexity increases
Solution Approach 1:
The cold plastic working is performed before applying the hard chrome layer. This preliminary action creates a hardened base that provides excellent adhesion for the subsequent chrome plating, ensuring the durability and fatigue strength of the coating while maintaining a relatively simple manufacturing process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the wear resistance and positioning accuracy of solenoid valves, ensuring precise operation and extended lifespan by combining hard chrome plating with localized cold forming, thereby improving the solenoid valve's durability and operational efficiency.
Implementation Method 1
the hard chrome layer makes the stop harder and at the same time allows magnetic separation when the armature is struck, which at least reduces magnetic sticking of the armature to the stop
Implementation Method 2
only the end region facing the armature or the relevant end face of the pole core is designed to be plastically cold-formed
Implementation Method 3
a soft-annealed stainless ferritic steel--for example made of a '1.4511' material--has good soft-magnetic properties
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a solenoid valve, in particular a quantity control valve (12) for a high-pressure fuel pump, with a pole core (38) and an axially movable armature (18), wherein an end face (37) of the pole core (38) forms a stop (39) for the armature (18), and wherein the pole core (38) is made of a stainless ferritic steel and the end face (37) of the pole core (38) forming the stop (39) is present at a section (50b) produced by plastic cold forming.