Transformer Winding Scheme for Automated Ignition Step-Up Converter

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Solution Overview

Problem

Existing step-up converters for ignition systems in internal combustion engines face challenges in automating the manufacture of toroidal transformers due to complex insulation requirements and the unavailability of suitable wires for high voltages, leading to increased costs and difficulties in compact design.

Innovation Solution

A step-up converter design featuring a multi-layer wound secondary coil with a coaxially wound primary coil, using thin lacquer insulation and a compact pot core structure with chamber walls to minimize additional insulation and facilitate automated manufacturing, allowing for efficient electrical isolation and reduced volume.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a toroidal transformer is used in a step-up converter for ignition systems, then the transformation ratio can reduce the voltage at the switch to acceptable levels, but the toroidal windings are difficult to automate and require complex insulation measures

Engineering Contradiction:
Improvevoltage isolationVSAvoidautomation difficulty
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The transformer is divided into a primary coil and a secondary coil with distinct winding layers. The secondary coil is multi-layer wound first, then the primary coil is wound coaxially over the outermost layer of the secondary coil. This segmentation allows each coil to be wound independently using automated machinery, resolving the automation difficulty while maintaining voltage isolation through the layered structure and thin lacquer insulation between coils.

Inventive Principle:
Principle #1Segmentation

2Reliability

If standard wires are used for high voltage isolation in toroidal transformers, then the insulation requirements can be met, but the wire outside diameter is too large for compact transformer design

Engineering Contradiction:
Improveelectrical insulationVSAvoidtransformer volume
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

Instead of using thick insulation wires, the patent employs thin lacquer insulation layers between the primary and secondary windings. The secondary coil is multi-layer wound with thin insulation between layers, and the primary coil is wound over the outermost layer of the secondary coil with thin lacquer insulation. This thin-film insulation approach provides adequate electrical isolation while maintaining a compact transformer volume suitable for ignition systems.

Inventive Principle:
Principle #30Flexible shells and thin films

3Reliability

If complex insulation measures are implemented for high voltage isolation, then electrical isolation can be ensured, but the volume and cost of the transformer increase

Engineering Contradiction:
Improveelectrical isolationVSAvoidtransformer volume
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent applies thin lacquer insulation locally at critical interfaces between windings rather than using comprehensive thick insulation throughout. The secondary coil has thin insulation between its multi-layers, and the primary coil is wound over the outermost layer of the secondary coil with thin lacquer insulation. This localized insulation approach provides adequate electrical isolation at the necessary points while minimizing overall transformer volume and cost.

Inventive Principle:
Principle #3Local quality

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 solution enables simplified and automated insulation measures, reducing the volume and cost of the transformer while ensuring reliable electrical isolation, allowing for the use of standard electronic switches and achieving the required high output voltage without exceeding their switching limits.

Implementation Method 1

The transformer with a primary coil (31) and a secondary coil (32)... During the switch-on phase of the step-up converter's switch, energy is loaded into the inductance (storage inductor) of the step-up converter. When the switch is open, this is transferred to the output capacitor via the diode of the step-up converter.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The windings of the transformer itself can be galvanically isolated from each other. For this purpose, the wires of the coils can be electrically insulated from one another, for example by means of thin layers of lacquer.

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Data Source

PatentEP3169891B1Winding scheme for a transformer of a step-up converter and ignition system for supplying a spark gap of an internal combustion engine with electric energy
Publication Date: 2018.03.28 ROBERT BOSCH GMBH
  • EP3169891B1 patent drawingFigure 1~2
  • EP3169891B1 patent drawingFigure 3
  • EP3169891B1 patent drawingFigure 4a

AI summary

A step-up converter and an ignition system with a step-up converter are proposed, which permit better automated production and reduced electrical insulation measures by way of a step-up converter having the following structure: - a transformer (3) with a primary coil (31) and a secondary coil (32) galvanically separated from the primary coil, wherein - the secondary coil (32) is wound in multiple layers and - the primary coil (31) is wound coaxially with respect to the secondary coil (32) over an outermost layer of the secondary coil (32), wherein - a first electrical terminal (32a) of the secondary coil (32) branches off an innermost layer of the secondary coil (32) , characterized in that - the first electrical terminal (32a) of the secondary coil (32) is designed for electrical connection to a high-voltage terminal for the spark gap.