Capacitive Horn Module for Wear-Free Steering Wheel Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing horn modules for vehicle steering wheels face challenges in being reliable, space-saving, and cost-effective, often relying on wear-prone mechanical contacts that can be impaired by wear and tear, and lack precise stroke detection.
Innovation Solution
A horn module utilizing a capacitive sensor unit with overlapping electrodes that change capacitance upon displacement, allowing for precise detection and triggering of a horn signal without mechanical contacts, featuring a frame and carriage design with electrodes oriented for maximum overlap and a flexible sensor belt for assembly simplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical contacts are used for horn activation, then the structure is simple and cost-effective, but the contacts are wear-prone and can be impaired by wear and tear
Solution Approach 1:
The patent replaces the mechanical contact system with a capacitive sensor system. Instead of using physical contacts that close a circuit when pressed, the invention uses two electrodes that form a capacitor. When the triggering element is actuated, the distance between the electrodes changes, causing a detectable change in capacitance that triggers the horn signal without any mechanical contact closure.
Solution Approach 2:
The patent introduces an intermediary evaluation circuit that processes the capacitive signal. The evaluation circuit receives the raw capacitive signal from the sensor unit, evaluates whether the change in capacitance corresponds to a valid horn actuation, and only then triggers the horn signal. This intermediary layer filters out false signals and ensures reliable horn activation.
2Measurement precision
If mechanical contacts are used for horn activation, then the device is simpler, but the stroke detection precision is insufficient
Solution Approach 1:
The patent replaces mechanical stroke detection with capacitive sensing. Instead of detecting horn activation through mechanical contact closure, the system uses a capacitive sensor unit with two electrodes whose capacitance changes as the triggering element moves. This allows for precise measurement of the stroke distance and detection of the actuation event.
Solution Approach 2:
The patent exploits the parameter change in capacitance as the triggering element is actuated. As the distance between the two electrodes changes during horn activation, the capacitance of the sensor unit changes accordingly. The evaluation circuit detects this parameter change and uses it to precisely determine when and how much the horn has been actuated.
3Reliability
If a capacitive sensor system with two electrodes is used, then wear is reduced and detection precision is improved, but the device complexity increases
Solution Approach 1:
The patent merges the capacitive sensor unit and the evaluation circuit into an integrated horn module. The sensor unit with its two electrodes is positioned within the airbag module housing, and the evaluation circuit is integrated into the same module, allowing for compact arrangement and simplified installation as a complete unit in the steering wheel.
Solution Approach 2:
The horn module is designed as a universal assembly that can be integrated into various steering wheel configurations. The module combines multiple functions including the capacitive sensor for wear-free detection, the evaluation circuit for signal processing, and the horn signal generation, making it a multi-functional unit that can be applied across different vehicle models.
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 provides a reliable, precise, and cost-effective horn module with reduced wear and improved detection accuracy, ensuring robust and error-free operation by leveraging capacitive sensing for horn activation.
Implementation Method 1
The sensor unit has a first electrode and an opposite second electrode, which can be displaced relative to one another in a displacement direction by actuation of a triggering element in such a way that the extent of the overlapping of the electrodes is changed as a result
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A horn module (10) for a vehicle steering wheel comprises at least one capacitive sensor unit (24) for detecting a horn operation, and also an electronics unit (18) for signal processing and evaluation and for tripping a horn signal. The sensor unit (24) has a first electrode and an opposite second electrode which can be displaced relative to one another by operation of a tripping element in a displacement direction (F) such that the extent of the overlap of the electrodes (12, 22) changes as a result. A horn module (10) of this kind can be part of an assembly (44) for a vehicle steering wheel which comprises a driver airbag module (16) and the horn module (10) which is fitted to it.