Ignition Transformer Non-Linear Secondary Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Modern spark ignition internal combustion engines require high initial ignition discharge energy for reliable combustion initiation but extended high discharge currents lead to undesirable spark plug electrode erosion, and dual coil systems increase costs.
Innovation Solution
An ignition transformer with a central core, primary coil, secondary coil, and magnetic return path, where the permeability of the return path is selected to achieve a non-linear secondary-current versus time-response characteristic, decaying to 50% of the initial current within 10-25% of the burn-time interval, mimicking the performance of dual coil systems with a single secondary coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extended high discharge current is used, then combustion repeatability is improved, but spark plug electrode erosion increases
Solution Approach 1:
The patent applies dynamics by making the discharge current time-dependent rather than constant. The current starts high to ensure reliable combustion initiation and then decays to a lower sustained level that maintains combustion repeatability while reducing electrode erosion. This is achieved through a transformer with a non-linear secondary current characteristic that automatically provides the desired current profile over time.
Solution Approach 2:
The patent changes the current parameter over time by designing a transformer with specific magnetic core properties (initial permeability of 10-100) that cause the secondary current to decay from an initial high value to a lower sustained value. This parameter change allows the system to achieve both high initial discharge energy for reliable ignition and reduced sustained current to minimize electrode erosion.
2Reliability
If dual coil system is used, then high initial discharge current and extended discharge current are provided, but system cost increases
Solution Approach 1:
The patent merges the functions of two separate ignition coils into a single transformer. Instead of using two isolated coils with high voltage diodes to combine outputs, this invention uses one transformer with a non-linear current characteristic that inherently provides both the high initial discharge current and the extended lower discharge current, thereby reducing component count and system cost.
Solution Approach 2:
The single transformer is designed to perform multiple functions that previously required two separate coils: it provides both the high initial discharge current for combustion initiation and the extended discharge current for maintaining combustion repeatability. The non-linear current characteristic enables this multi-functionality within a single device.
3Reliability
If high initial discharge current is provided, then combustion initiation is improved, but electrode erosion increases
Solution Approach 1:
The patent implements periodic action through the time-varying current profile. The current is high during the initial period to ensure reliable combustion initiation, then automatically decays to a lower level for the extended period. This periodic variation in current magnitude allows the system to achieve reliable ignition without subjecting the electrodes to continuous high current stress that would cause excessive erosion.
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 transformer provides high initial secondary current for reliable combustion initiation and reduced subsequent current for extended spark duration, comparable to dual coil systems but at lower cost, using a single secondary coil and optimized magnetic materials.
Implementation Method 1
The primary coil is used to vary magnetic energy into the central core in response to the primary current applied to the primary coil
Implementation Method 2
The secondary coil is used to generate a secondary voltage in response to changes in the magnetic energy in the central core
Implementation Method 3
The magnetic return defines the return-path to couple magnetic energy from the first end to the second end
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An ignition transformer (10) for use with a spark ignition system (12) for an internal combustion engine (18) includes a central core (20), a primary coil (22), a secondary coil (24), and a magnetic return (28). The central core (20) defines a first end (20A) and a second end (20B). The primary coil (22) is used to vary magnetic energy into the central core (20) in response to a primary current (52) applied to the primary coil (22). The secondary coil (24) is used to generate a secondary voltage (56) in response to changes in the magnetic energy in the central core (20). The magnetic return (28) defines a return-path (58) to couple magnetic energy from the first end (20A) to the second end (20B). A permeability value of the return-path (58) is selected so the transformer (10) has a secondary-current versus time-response characteristic (400) that decays to fifty-percent (50%) of an initial secondary current (410) when ten percent (10%) to twenty-five percent (25%) of a burn-time interval (420) has passed.