Ignition Coil Magnetic Core Segmentation for Winding Insulation
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Solution Overview
Problem
Existing ignition coils for internal combustion engines face challenges in achieving optimal magnetic properties and uniform electrical insulation due to geometric design issues, particularly in corner areas where wire withdrawal speeds are high, leading to reduced insulation capacity and magnetic core utilization.
Innovation Solution
The ignition coil design features an inner magnetic core with lamellar sheet metal strips, where the uppermost and lowermost strips have a reduced width, creating stepped corner regions that allow for a larger radius and uniform resin filling, reducing wire tension and enhancing insulation in corner areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the inner magnetic core has a rectangular cross-section with rounded edges, then the cross-sectional area is maximized for good magnetic properties, but the wire withdrawal speed increases in corner areas causing compression of wire layers and poor insulation
Solution Approach 1:
The patent divides the magnetic core into multiple segments with different cross-sectional shapes along its length. The first section has a rectangular cross-section with rounded edges for optimal magnetic properties, while the second section has a circular cross-section that reduces wire withdrawal speed during winding. This segmentation allows each section to serve its specific function without compromising the other.
Solution Approach 2:
The patent applies different geometric qualities to different parts of the magnetic core. The first section maintains a rectangular cross-section with rounded edges to maximize magnetic core area, while the second section transitions to a circular cross-section to optimize winding characteristics. This local differentiation resolves the contradiction by allowing each region to have the quality needed for its specific function.
2Manufacturing precision
If the inner magnetic core uses a circular cross-section, then wire withdrawal speed is reduced and insulation is improved, but the cross-sectional area is reduced compromising magnetic properties
Solution Approach 1:
The magnetic core is segmented into two sections: the first section with rectangular cross-section for magnetic optimization and the second section with circular cross-section for winding optimization. This allows the system to achieve both goals without compromise by distributing functions across different segments.
Solution Approach 2:
The patent resolves the contradiction by adding a dimensional element - the magnetic core extends in the longitudinal direction with different cross-sectional shapes at different positions. This transforms a two-dimensional cross-sectional choice into a three-dimensional solution where both rectangular and circular sections coexist along the core's length.
3Productivity
If the wire is wound at high angular speeds, then productivity is improved, but the wire tension increases in corner areas causing compression and poor resin impregnation
Solution Approach 1:
The magnetic core is designed with a circular cross-section in the second section before the winding process begins. This preliminary geometric configuration reduces the wire withdrawal speed during high-speed winding, preventing wire layer compression and ensuring proper resin impregnation quality even at high productivity levels.
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 maximizes the magnetic core's cross-sectional area utilization, reduces wire tension in corner areas, and ensures better impregnation and electrical insulation, improving the overall performance of the ignition coil.
Implementation Method 1
The primary coil (18) has a primary winding (21) which is wound onto a primary bobbin (22). The secondary coil (19) has a secondary winding (23) which is located on a secondary coil former (24).
Implementation Method 2
the gaps between the inner magnetic core, the primary coil with its primary bobbin and the secondary coil with its secondary bobbin are surrounded by an insulating compound, in particular an insulating resin, which provides electrical insulation between the live parts
Data Source
Figure 1~2
Figure 3~6
AI summary
An ignition coil (10), especially for an internal combustion engine of a motor vehicle, has an internal magnetic core (26) which is concentrically surrounded by a primary spool (18) and a secondary spool (19). The internal magnetic core (26) is made up of strips of sheet metal layered over each other (30, 30a; 30, 30b, 30c), whereby the strips of sheet metal (30, 30a; 30, 30b, 30c) primarily form a rectangular and/or square cross sectional area of the internal magnetic core (26). The invention distinguishes itself in terms of the lower and upper strips of sheet metal forming the boundary of the internal magnetic core (26) which is reduced in width (b), at least in the areas opposite the other strips of sheet metal (30) of the internal magnetic core (26) when viewed laterally. This makes possible a primary spool body (22) and/or secondary spool body (24) with an enlarged corner radius (r) and uniform winding density of the primary spool (18) and/or the secondary spool (19) possible.