Ignition System Spark Plug Noise Reduction
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Solution Overview
Problem
The increasing number of electronics in vehicles is affected by electromagnetic noise generated by spark plug discharges in internal combustion engine ignition systems, necessitating a technique to restrain radiation noise.
Innovation Solution
An ignition system design that includes a spark plug with a metallic shell grounded through an electrically conductive path insulated from the engine head, and an optional grounded shield connected to the battery's ground terminal, reducing current flow to the engine head and minimizing noise radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If current flows through the engine head during spark plug discharge, then the discharge function is achieved, but electromagnetic noise is generated and affects vehicle electronics
Solution Approach 1:
The patent introduces an electrically conductive path as an intermediary element between the spark plug and ground terminal. This conductor provides a dedicated low-impedance path for discharge current, preventing it from flowing through the engine head. The conductor acts as a mediator that redirects current flow to achieve noise reduction without compromising the spark plug's ignition function.
Solution Approach 2:
The patent segments the current path into distinct components: the spark plug electrode, the electrically conductive path, and the ground terminal. By separating the current flow path from the engine head structure, the design isolates the electromagnetic noise source and directs current through a controlled pathway, thereby reducing radiated interference while maintaining ignition effectiveness.
2Object-affected harmful factors
If the shield is connected to the engine head, then the shield structure is simplified, but noise transfers from the engine head to the shield making it a noise source
Solution Approach 1:
The patent uses the electrically conductive path as an intermediary that connects the shield to the ground terminal without direct connection to the engine head. This intermediary connection prevents noise transfer from the engine head to the shield while still providing effective electromagnetic shielding. The conductor mediates between the shield and ground, isolating the shield from engine head noise.
Solution Approach 2:
The patent extracts the shield connection from the engine head structure and creates an independent connection path to the ground terminal. By taking out the shield connection from the engine head and establishing a separate conductive path, the design prevents noise transfer while maintaining the shield's protective function.
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 design effectively reduces noise radiation by minimizing the current loop area and preventing the engine head from becoming a noise source, thereby protecting vehicle electronics from electromagnetic interference.
Implementation Method 1
an ignition coil which transforms a voltage of the battery and supplies a transformed voltage to the spark plug
Implementation Method 2
a discharge of the spark plug is known to generate electromagnetic noise
Implementation Method 3
an electrically conductive path connected to the metallic shell, and the electrically conductive path is electrically connected to the ground terminal while being electrically insulated from the engine head
Implementation Method 4
the metallic shell is fixed to the engine head while being electrically insulated from the engine head through a second insulator
Implementation Method 5
a grounded electrically conductive shield which extends from a terminal side and surrounds at least a portion of the spark plug
Data Source
AI summary
An ignition system that uses a technique capable of restraining radiation of noise caused by discharge of a spark plug in the ignition system. The ignition system includes a spark plug and a power supply section. The spark plug is attached to an engine head. The power supply section has a battery having a ground terminal, and an ignition coil which transforms a voltage of the battery and supplies a transformed voltage to the spark plug. In the ignition system, a metallic shell of the spark plug is fixed to the engine head while being electrically insulated from the engine head through an insulator; an electrically conductive path is connected to the metallic shell; and the electrically conductive path is electrically connected to the ground terminal of the battery while being electrically insulated from the engine head.