Watertight Capacitive Sensor Unit With Embedded Electrode Strip
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Solution Overview
Problem
Existing capacitive sensors for anti-pinch devices in motor vehicles face challenges in protecting electrodes from water and dirt while maintaining complex geometric forms and multilayer electrode structures, especially when used in exposed and chemically aggressive environments like the edges of moving vehicle parts.
Innovation Solution
A capacitive sensor unit is produced using a U-shaped carrier made from water-impermeable material, where an electrode strip is embedded within a hardening filler material, allowing for flexible geometric forms and multilayer electrode systems, and the sensor unit can be bent into a three-dimensional shape for installation, with the filler material providing watertight encapsulation and mechanical fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrodes are protected by coextrusion in a flexible tubular hollow form, then electrodes are reliably protected from water and dirt, but only relatively simple electrode structures can be realized at reasonable cost
Solution Approach 1:
The sensor unit is divided into separate functional components: a carrier structure and an electrode assembly. The electrode strip with multiple electrode layers is manufactured separately and then integrated into the carrier, allowing complex electrode structures to be realized without complicating the protective housing structure.
Solution Approach 2:
The electrode strip with its multiple electrode layers is nested within the carrier structure. The electrode assembly is placed inside the carrier's interior space and surrounded by filling material, creating a nested configuration that protects complex electrode structures while maintaining a simple external protective form.
2Device complexity
If multiple electrode layers are placed side-by-side in the hollow body, then multilayer electrode structures are achieved, but production cost increases significantly
Solution Approach 1:
The electrode strip with multiple electrode layers is pre-assembled as a complete unit before integration into the carrier. This preliminary assembly allows the complex multilayer structure to be manufactured using standard, cost-effective techniques, and then the entire assembly is simply inserted into the carrier for final integration.
Solution Approach 2:
The electrode strip serves as a template or copy of the desired electrode configuration. By manufacturing the electrode pattern separately on a flexible substrate and then transferring it into the carrier, complex electrode geometries can be reproduced without requiring complex tooling or assembly processes for the final product.
3Length of moving object
If the sensor is dimensioned for large structural parts, then coverage of extensive closing edges is achieved, but electrode protection becomes more difficult
Solution Approach 1:
The carrier is constructed as a flexible, elongated structure that can be bent and conform to long, complex closing edges of large vehicle structural parts. This flexible carrier maintains its protective enclosure for the electrodes while adapting to extended geometries, ensuring continuous protection along the entire sensor length.
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 reliable protection of electrodes from environmental factors, facilitates complex geometric designs, and allows for cost-effective production of multilayer systems, ensuring effective detection of pinch events while being adaptable to various installation situations.
Implementation Method 1
The interior space is filled with a hardening filler material, such that the electrode strip is enclosed in a watertight manner between the carrier and the filling (in the hardened state of the filler material).
Implementation Method 2
capacitive sensors are used for this purpose. A capacitive sensor of this type comprises one or more electrodes with which an electric field is generated in the pinch region. To detect a case of pinching, the electrical capacitance is measured and evaluated
Implementation Method 3
the effect is utilized that a foreign object intruding into the pinch region, particularly a human body part, changes the electric field and thereby the measured capacitance
Data Source
AI summary
An apparatus and production method for a watertight capacitive sensor unit is provided. Accordingly, a carrier, approximately U-shaped in cross section, is made from a water-impermeable material. At least one electrode strip is placed in an interior space of the carrier along the longitudinal extension of the carrier. The interior space is filled with a hardening filler material in such a way that the electrode strip is sealed outwardly watertight.