Capacitive Vehicle Sensor Wiring for EMI-Resistant Flap Actuation
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Solution Overview
Problem
Capacitive sensor units for contactless actuation of vehicle doors or flaps face interference issues due to supply lines, leading to incorrect triggering or failure in operation, and are mechanically rigid, making installation challenging.
Innovation Solution
A sensor unit design with separate, twisted, and insulated supply lines, using coaxial cables with a shielding conductor and a galvanically isolated inner core, and optionally cable strands for increased flexibility and reduced interference, along with sealing elements to protect against moisture and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If connecting wires are used to electrically connect capacitive sensor elements, then electrical control is enabled, but electromagnetic interference occurs leading to false triggering
Solution Approach 1:
The patent applies the blessing in disguise principle by using the connecting wires themselves as shield conductors. The outer insulation layer of each cable is electrically connected to the shield conductor, and the connecting wires are twisted together to form a shielded structure. This converts the potentially harmful electromagnetic interference into a beneficial shielding effect, where the connecting wires become part of the interference protection system rather than just signal transmission paths.
Solution Approach 2:
The patent employs composite materials by combining multiple conductive and insulating layers within the cable structure. Each cable consists of an inner conductor for signal transmission, an outer insulation layer, and the shield conductor formed by twisted connecting wires. This composite structure integrates both signal transmission and electromagnetic shielding functions into a single integrated component, reducing interference while maintaining electrical connectivity.
2Measurement precision
If capacitive sensor elements are made rigid for structural stability, then measurement precision is maintained, but installation flexibility is reduced
Solution Approach 1:
The patent applies segmentation by dividing the sensor system into modular components: capacitive sensor elements, connecting wires with integrated shielding, and sealing elements. Each component can be independently manufactured and tested, then assembled during installation. This modular approach allows the sensor elements to maintain their precise rigid structure while the flexible connecting wires and easy-to-install sealing elements provide the necessary installation flexibility.
3Reliability
If control unit is placed close to capacitive sensors, then signal transmission is improved, but available space is insufficient
Solution Approach 1:
The patent uses the sealed cable assembly as an intermediary between the capacitive sensor elements and the control unit. The cable includes integrated shielding and sealing elements that protect the signal transmission path from electromagnetic interference and environmental factors. This allows the control unit to be positioned at a reasonable distance from the sensors while maintaining signal integrity through the protected transmission path, eliminating the need for tight spatial coupling.
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 significantly reduces electromagnetic interference, enhances mechanical flexibility, and minimizes errors during operation, ensuring reliable and efficient contactless actuation of vehicle doors or flaps.
Implementation Method 1
the shield conductor is designed as a shield for the other conductor
Implementation Method 2
the connecting wires are twisted together at least partially between the connector and the sensor element
Implementation Method 3
at least two connecting wires, namely a first and a second connecting wire, are galvanically isolated from each other
Data Source
Figure 1~2
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AI summary
The invention relates to a sensor unit (10) for contactless actuation of an actuator (101), in particular a flap (101), door (101) or the like of a vehicle (100), with at least one capacitive sensor element (11, 12) and a connecting line (11.a, 12.a) to each capacitive sensor element (11, 12), wherein the connecting line (11.a, 12.a) is connected on one side to the respective capacitive sensor element (11, 12) and on the other side to at least one connector (15), and wherein the sensor element (11, 12) has at least one cable (13) with two mutually insulated conductors (13.1, 13.2), wherein at least one shielding conductor (13.1) is designed as a shield for the other conductor (13.2), and the shielding conductor (13.1) is designed as a braided or The foil screen is designed, and the supply line (11.a, 12.a) has at least two spatially separated and insulated supply wires (11.a1, 2, 12.a1, 2). According to the invention, the supply wires (11.a1, 2, 12.a1, 2) between the connector (15) and the sensor element (11, 12) are at least partially twisted together, and at least two supply wires (11.a1, 2, 12.a1, 2), namely a first and second supply wire (11.a1, 2, 12.b1, 2), are galvanically isolated from each other, wherein the first supply wire (11.a1, 12.a1) is electrically conductively connected to the shield conductor (13.1) of the sensor element (11, 12), and the second supply wire (11.a2, 12.a2) is only electrically conductively connected to the connector (15) and is led to the sensor element (11, 12). Furthermore, the invention is also directed to a sensor system (50) and a vehicle (100) with such a sensor system (50).