Ignition System Shield Electrode Air Gap Control
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Solution Overview
Problem
Existing ignition systems, such as those described in U.S. Pat. No. 5,189,333, suffer from inconsistent ignition due to poorly positioned ground electrodes, leading to fouling and arcing outside the intended ignition area, which affects the reliability and consistency of air-fuel mixture ignition in regeneration devices for exhaust treatment systems.
Innovation Solution
The proposed ignition system features a separate ground terminal positioned relative to the center electrode to form a consistent air gap, with the ground terminal mounted on a component like the swirl plate, allowing for precise control of the ignition area and reducing fouling through pressurized air flow, enhancing the probability of ignition and preventing arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ground electrode is positioned close to the central electrode to form an air gap, then ignition can occur, but fouling and arcing outside the ignition area develop
Solution Approach 1:
The patent introduces a shield electrode as an intermediary component positioned between the ground electrode and central electrode. This shield electrode acts as a mediator that prevents direct arcing and fouling between the main electrodes while maintaining the necessary electric field for ignition. The shield electrode captures and redirects electrical discharge away from the ignition area, solving the contradiction between achieving reliable ignition and preventing harmful arcing.
Solution Approach 2:
The patent divides the ground electrode into two separate components: the main ground electrode and the shield electrode. This segmentation allows the ground electrode system to perform multiple functions - the main ground electrode provides the primary electrical connection while the shield electrode specifically prevents fouling and arcing. By separating these functions into distinct components, the system achieves both reliable ignition and protection against harmful effects.
2Ease of manufacture
If the ground electrode is poorly positioned relative to the central electrode, then the device structure is simpler, but ignition becomes inconsistent
Solution Approach 1:
The patent positions the shield electrode at a specific distance from the central electrode that creates an equipotential region. This positioning ensures that the electric field is properly distributed and that ignition occurs consistently at the intended location. The shield electrode's position is designed to create a uniform electrical environment that promotes reliable ignition while preventing discharge in unwanted areas.
Solution Approach 2:
The shield electrode serves as a positioning reference and electrical mediator that ensures consistent spacing between the ground electrode and central electrode. By introducing this intermediate component with a defined position, the system achieves reproducible ignition conditions without requiring complex positioning mechanisms, thus maintaining ease of manufacture while improving ignition reliability.
3Reliability
If the air gap between electrodes is reduced to improve ignition probability, then ignition becomes more reliable, but arcing outside the air gap increases
Solution Approach 1:
The shield electrode is positioned between the central electrode and ground electrode to intercept and redirect electrical discharge. When the air gap is reduced for better ignition probability, the shield electrode prevents the resulting higher energy discharge from causing external arcing. It acts as a protective intermediary that allows the use of smaller air gaps without increasing harmful arcing effects.
Solution Approach 2:
The patent applies different functional qualities to different parts of the electrode system. The region between the central electrode and shield electrode is optimized for ignition with a small air gap, while the region between the shield electrode and ground electrode is designed to prevent external arcing. This local differentiation of electrical properties allows the system to achieve high ignition probability while containing harmful discharge effects.
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
This configuration ensures a consistent and reliable ignition area, improving the probability of successful ignition and reducing fouling and arcing, while allowing for a smaller electrical energy delivery device housing and enhanced air-fuel mixture quality.
Implementation Method 1
An air-fuel mixture may be ignited by a spark discharge in an air gap between the central electrode and the parallel ground electrode
Data Source
AI summary
An ignition system includes an electrical energy delivery device having a first electrode terminating at a first end portion and a second electrode positioned in the ignition system separately from the electrical energy delivery device. The second electrode terminates at a second end portion disposed a first distance from the first end portion to form an air gap therebetween. The air gap forms an area including the shortest distance between the first electrode and the second electrode.