Rigid-Flex Steering Control PCB for Compact Motor Current Routing

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Solution Overview

Problem

The increasing complexity of motor vehicle control devices for steering systems requires smaller, more compact designs to manage limited installation space, while also simplifying assembly and testing, as traditional multiboard systems are cumbersome and difficult to inspect visually when assembled.

Innovation Solution

A control device with device electronics arranged on a rigid-flex circuit board, combining two rigid circuit carriers connected by flexible sections, allowing for space-efficient installation and simplified assembly, with the power module and control electronics on separate carriers, reducing the need for plug connections and enabling pre-installation functionality checks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If multiple separate circuit boards are used to arrange device electronics, then the control unit can be assembled modularly, but the installation space required increases and assembly complexity increases

Engineering Contradiction:
Improvemodular assemblyVSAvoidinstallation space
Core Design Contradiction:
Ease of manufactureVSArea of stationary object

Solution Approach 1:

The patent combines multiple separate circuit boards into a single integrated circuit board that houses all device electronics including control electronics, power module, and power supply. This merging eliminates the need for multiple connectors and reduces installation space while maintaining modular assembly capabilities through the integrated design.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If multiple separate circuit boards are used, then component testing can be done individually, but the number of connectors increases and assembly becomes more difficult

Engineering Contradiction:
Improvecomponent testingVSAvoidnumber of connectors
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates the power module and control electronics onto a single circuit board, eliminating the need for connectors between these components. This reduces device complexity and assembly difficulty while maintaining the ability to test components individually during the manufacturing process.

Inventive Principle:
Principle #5Merging (Combining)

3Area of stationary object

If a single large circuit board is used to arrange all device electronics, then installation space is reduced, but visual inspection and testing become more complex

Engineering Contradiction:
Improveinstallation spaceVSAvoidvisual inspection
Core Design Contradiction:
Area of stationary objectVSDifficulty of detecting and measuring

Solution Approach 1:

The patent segments the circuit board into distinct functional areas with clearly defined regions for control electronics, power module, and power supply. This segmentation is achieved through separate rigid circuit carriers connected by flexible sections, allowing visual inspection and testing to be performed on manageable sections while maintaining a compact overall design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses a three-dimensional arrangement with rigid circuit carriers connected by flexible sections, allowing the circuit board to fold or bend to fit within compact spaces. This dimensional approach enables compact installation while maintaining accessibility for visual inspection and testing of individual components.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Ease of manufacture

If rigid circuit boards are connected using traditional connectors, then assembly is simplified, but the connectors occupy significant installation space

Engineering Contradiction:
Improveassembly simplicityVSAvoidconnector space
Core Design Contradiction:
Ease of manufactureVSArea of stationary object

Solution Approach 1:

The patent replaces traditional bulky connectors with thin flexible circuit sections that connect rigid circuit carriers. These flexible sections act as interconnectors while occupying minimal space, enabling simple assembly through flexible connections rather than rigid connector assemblies.

Inventive Principle:
Principle #30Flexible shells and thin films

Data Source

PatentEP3935718B1Control device for a steering system of a motor vehicle, electromechanical power steering mechanism for a motor vehicle and steer-by-wire steering system
Publication Date: 2024.01.17 THYSSENKRUPP AG
  • EP3935718B1 patent drawingFigure 1~2
  • EP3935718B1 patent drawingFigure 3~4

AI summary

The invention relates to a control device for a steering system of a motor vehicle, having device electronics (30) which are arranged on a printed circuit board (20) and comprise control electronics (31), a power module (32) and a current supply (33), the control electronics (31) being configured to process input signals so as to output control signals to the power module (32), and the power module (32) having contact points (34) for connecting a steering servomotor for actuating the steering servomotor depending on the control signals, characterised in that the printed circuit board (20) is designed as a rigid-flex circuit board with at least two rigid circuit carriers (22, 23) connected by at least one first flexible portion (21), wherein the control electronics (31) and the power module (32) are arranged on their own one of the circuit carriers (22, 23) and, for the current supply (33), a second flexible portion (24) of the circuit board (20) is formed on the circuit carrier (23) of the power module (32). The invention also relates to an electromechanical power steering mechanism for a motor vehicle and to a steer-by-wire steering system having a control device of this kind.