Injection Valve Two-Stage Tempering for Wear and Fracture Control
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Solution Overview
Problem
Injection valves used in internal combustion engines experience structural transformation during initial engine operation, leading to changes in injection quantity and wear issues, which are not optimally addressed by current hardening and tempering processes.
Innovation Solution
A two-stage heat treatment process is applied to the injection valve, with the first tempering at a lower temperature to reduce internal stresses and the second tempering at a higher temperature specifically targeting the valve seat area, combined with inductive heating to simulate operational conditions, ensuring consistent injection properties and preventing brittle fracture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the valve body is tempered at higher temperatures for longer time, then the toughness of the steel is improved, but the hardness decreases leading to increased wear
Solution Approach 1:
The tempering process is divided into two separate stages: first tempering (150-250°C) to reduce internal stresses while maintaining hardness, and second tempering (250-450°C) to improve toughness in the valve seat area. This segmentation allows different regions of the valve body to achieve different property profiles optimized for their specific functional requirements.
Solution Approach 2:
The second tempering is applied selectively to specific areas of the valve body, particularly the valve seat region, at higher temperatures to locally improve toughness where brittle fracture is most likely to occur, while the needle guide area retains higher hardness from the first tempering to maintain wear resistance.
2Reliability
If the valve body is tempered at lower temperatures or for shorter time, then the wear resistance is maintained, but the valve body remains brittle and cracks can occur
Solution Approach 1:
The tempering process is divided into two separate stages: first tempering (150-250°C) to reduce internal stresses while maintaining hardness, and second tempering (250-450°C) to improve toughness in the valve seat area. This segmentation allows different regions of the valve body to achieve different property profiles optimized for their specific functional requirements.
Solution Approach 2:
The second tempering is applied selectively to specific areas of the valve body, particularly the valve seat region, at higher temperatures to locally improve toughness where brittle fracture is most likely to occur, while the needle guide area retains higher hardness from the first tempering to maintain wear resistance.
3Ease of manufacture
If conventional single-stage tempering is used, then the manufacturing process is simple, but structural transformation occurs during initial engine operation leading to changes in injection quantity
Solution Approach 1:
The two-stage tempering process is designed to anticipate and complete the structural transformation that would otherwise occur during initial engine operation. By performing the transformation-controlled second tempering during manufacturing, the valve body's microstructure is stabilized before service, preventing subsequent changes in injection quantity and ensuring consistent performance throughout the valve's service life.
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 method maintains the hardness of the valve needle guide area while increasing the toughness of the valve seat, preventing changes in injection behavior and wear, thus ensuring consistent performance throughout the service life of the valve.
Implementation Method 1
heating by means of an induction process has proven to be particularly advantageous
Implementation Method 2
the hardening process is followed by a heat treatment in which the entire valve body is heated
Data Source
Figure 1
Figure 2~4
AI summary
The invention relates to a method for producing an injection valve for liquids, preferably an injection valve for injecting fuel into a combustion chamber of an internal combustion engine, which injection valve has a valve body (1), with a valve seat (6) which is formed therein, and a valve needle (5) which interacts with the valve seat (6) in order to open and close at least one injection opening (7). The injection valve is produced by means of the following method steps: producing the valve body (1) from steel, hardening the valve body (1), annealing a partial region of the valve body (1) at an annealing temperature T2. The device for carrying out the method according to the invention comprises an inductive annealing generator which generates a suitable alternating current for operating a coil, in the magnetic field of which coil the valve body can be heated for annealing (figure 2).