Fuel Injection Valve Sacrificial Corrosion Layer
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Solution Overview
Problem
Fuel injection valves in internal combustion engines face corrosion issues due to condensed water containing sulfur and nitrogen, which accelerates oxidation and affects injection characteristics, especially with increased EGR amounts, and existing chromizing methods provide limited corrosion resistance.
Innovation Solution
A fuel injection valve design featuring a metallic base material with a sacrificial corrosion layer and a corrosion-resistant layer, where the sacrificial layer is more corrosive than the corrosion-resistant layer, both deposited via chemical vapor deposition, to protect the base material from corrosion by oxidizing condensed water before it reaches the base material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chromizing is applied to the valve body surface, then corrosion resistance is improved, but corrosion protection is insufficient under high EGR conditions with increased sulfur and nitrogen content
Solution Approach 1:
The protective coating is divided into multiple distinct layers: a chromizing layer (corrosion-resistant layer) and an intermediate layer (sacrificial corrosion layer) positioned between the base material and the chromizing layer. This segmentation allows each layer to perform its specific function - the intermediate layer sacrifices itself to protect the base material, while the chromizing layer provides additional corrosion resistance.
Solution Approach 2:
An intermediate layer is introduced as a mediator between the base material and the chromizing layer. This intermediate layer acts as a sacrificial element that preferentially corrodes to protect the base material from sulfur and nitrogen-containing condensed water, while the chromizing layer serves as the outer protective barrier.
2Object-generated harmful factors
If EGR amount is increased to reduce nitrogen oxide emissions, then emission control is improved, but corrosion of the valve body accelerates due to increased sulfur and nitrogen dissolution in condensed water
Solution Approach 1:
The sacrificial intermediate layer is pre-positioned between the base material and the environment before corrosion occurs. This preliminary protective measure ensures that when sulfur and nitrogen-containing condensed water comes into contact with the valve body, the intermediate layer is already in place to sacrifice itself and protect the base material, preventing corrosion before it can affect the critical injection hole.
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 effectively suppresses corrosion of the base material by allowing the sacrificial layer to oxidize condensed water, reducing the risk of corrosion and maintaining injection characteristics by preventing the water from reaching the base material, thus enhancing the valve's durability and performance.
Implementation Method 1
allowing the sacrificial layer to oxidize condensed water, reducing the risk of corrosion and maintaining injection characteristics by preventing the water from reaching the base material
Implementation Method 2
both deposited via chemical vapor deposition
Data Source
AI summary
A fuel injection valve includes a body that includes an injection hole through which fuel is injected, and a valve element that opens or closes the injection hole. The body includes a metallic base material configured to form the injection hole, a corrosion-resistant layer covering a surface of at least a part of the base material that forms the injection hole and being made of a less corrosive material than the base material, and a sacrificial corrosion layer located between the base material and the corrosion-resistant layer and made of a more corrosive material than the corrosion-resistant layer.