Spark Plug Resistor Layering for Durability and Noise Suppression
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Solution Overview
Problem
The demand for smaller and more powerful spark plugs in vehicular internal combustion engines, particularly in supercharged engines, necessitates high voltage application while maintaining electrical durability and radio noise suppression, which is compromised by increased titanium oxide content in resistor elements.
Innovation Solution
A spark plug design with a resistor element featuring a titanium oxide containing region near the center electrode and a titanium oxide reduced region near the metallic terminal member, ensuring a gradual decrease in titanium oxide content from the center electrode side to the metallic terminal member side, thereby enhancing electrical durability and radio noise suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of titanium oxide added to the resistor element is increased to enhance electrical durability, then the electrical durability is improved, but the radio noise suppression effect deteriorates
Solution Approach 1:
The patent applies local quality by creating a resistor element with non-uniform titanium oxide distribution. The first region (near center electrode) has higher titanium oxide content (5-20 mass%) to provide electrical durability, while the second region (near metallic terminal member) has lower or zero titanium oxide content to maintain radio noise suppression. This spatial variation in material composition resolves the contradiction between electrical durability and radio noise suppression.
Solution Approach 2:
The resistor element is segmented into two distinct regions with different titanium oxide contents. The first region contains titanium oxide for electrical durability, while the second region has reduced or no titanium oxide for radio noise suppression. This segmentation allows each region to optimize its local function without compromising the other.
2Power
If high voltage is applied to the spark plug for supercharged engines, then the power output is improved, but the electrical durability requirement increases
Solution Approach 1:
The first region of the resistor element has high titanium oxide content (5-20 mass%) specifically positioned near the center electrode to withstand high voltage conditions in supercharged engines. This localized enhancement provides the necessary electrical durability where the highest electrical stress occurs, enabling high power output without compromising reliability.
3Weight of moving object
If parts are switched from metal materials to non-metal materials such as carbon fiber composite material for weight reduction, then the vehicle weight is reduced, but the shielding performance is lost
Solution Approach 1:
The patent extracts the radio noise suppression function from the metallic shell and transfers it to the resistor element itself. By incorporating titanium oxide in the first region and reducing it in the second region, the resistor element gains inherent radio noise suppression capability, compensating for the loss of shielding performance when using non-metallic materials for other components.
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 spark plug achieves simultaneous electrical durability and radio noise suppression by strategically distributing titanium oxide content, stabilizing resistance and reducing noise leakage.
Implementation Method 1
Since the resistor element contains titanium oxide in this region, it is possible to suppress melting of glass, thereby enhancing electrical durability
Implementation Method 2
The resistor element functions as an electrical resistor between the metallic terminal member and the center electrode, thereby suppressing generation of radio noise at the time of spark discharge
Data Source
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AI summary
A spark plug 1 includes a tubular metallic shell 20, a tubular insulator 10 held in the metallic shell 20 and having an axial hole 11 extending in an axial direction, a center electrode 30 held at one end of the axial hole 11, a metallic terminal member 40 held at the other end of the axial hole 11, and a resistor element 50 disposed between the center electrode 30 and the metallic terminal member 40 in the axial hole 11 and containing glass and an electrically conductive material. The resistor element 50 has a first resistor layer 50A (titanium oxide containing region) which is disposed on a side toward the center electrode 30 and closest to the center electrode 30 and contains titanium oxide, and a second resistor layer 50B (titanium oxide reduced region) which is disposed on a side toward the metallic terminal member 40 in relation to the first resistor layer 50A and whose titanium oxide content is lower than that of the first resistor layer 50A. As a whole, the titanium oxide content decreases from the center electrode 30 side toward the metallic terminal member 40 side.