Spark Plug Resistor Segmentation for Radio Noise
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Solution Overview
Problem
The increasing voltage in internal combustion engines leads to higher radio noise from spark plugs, and increasing resistor resistance to reduce noise decreases ignition energy, deteriorating sparking performance.
Innovation Solution
A spark plug design with a resistor that has a higher center electrode-side resistance than metal terminal-side resistance, allowing for effective noise reduction without compromising ignition performance, achieved by varying the resistance materials and lengths in the connecting portion between the center electrode and metal terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the resistance of the resistor is increased to reduce radio noise, then the level of radio noise is reduced, but ignition energy decreases and sparking performance deteriorates
Solution Approach 1:
The resistor is segmented into two distinct resistance portions: a first resistance portion connected to the center electrode and a second resistance portion connected to the metal terminal. This segmentation allows each portion to have different resistance values, enabling the first portion to suppress radio noise while the second portion maintains sufficient ignition energy for sparking performance.
Solution Approach 2:
Different portions of the resistor are assigned different local qualities (resistance values). The first resistance portion has a higher resistance value optimized for radio noise suppression, while the second resistance portion has a lower resistance value optimized for maintaining ignition energy. This local differentiation resolves the contradiction between noise reduction and energy maintenance.
2Object-generated harmful factors
If a resistor with high resistance is used to suppress radio noise, then radio noise is reduced, but the overall resistance increases causing deterioration of sparking performance
Solution Approach 1:
The resistor is divided into two portions with different resistance values. The first portion (R1) has higher resistance for noise suppression, while the second portion (R2) has lower resistance to maintain overall resistance within acceptable ranges for reliable sparking. The total resistance is controlled by the series combination: R_total = R1 + R2.
Solution Approach 2:
The resistance parameter is changed differently in different portions of the resistor. By adjusting the resistance values of R1 and R2 independently, the patent achieves optimal balance between radio noise suppression (requiring higher R1) and sparking performance (requiring controlled R_total), resolving the contradiction through parameter optimization.
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 suppresses radio noise generation during spark discharge while maintaining ignition energy, with the center electrode-side resistance being at least 0.5 kΩ larger than the metal terminal-side resistance, reducing noise across a wide frequency range without deteriorating sparking performance.
Implementation Method 1
the level of radio noise generated by a spark plug can be reduced by increasing the resistance of a resistor disposed in a connecting portion that electrically connects a center electrode of the spark plug with its metal terminal
Data Source
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AI summary
The level of radio noise generated from a spark plug is reduced while deterioration of sparking performance is suppressed. The spark plug includes an insulator having an axial bore extending in an axial direction; a center electrode disposed at one end of the axial bore; a metal terminal disposed at the other end of the axial bore; and a connecting portion that electrically connects the center electrode with the metal terminal within the axial bore. The connecting portion of the spark plug includes a resistor. A center electrode-side resistance, which is the resistance of a portion of the resistor that extends from the center thereof toward the center electrode in the axial direction, is larger than a metal terminal-side resistance, which is the resistance of a portion of the resistor that extends from the center thereof toward the metal terminal.