Coaxial Cable Sensor for Extended Vehicle Door Detection Range
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Solution Overview
Problem
Existing vehicle door or hatch sensor units have a limited detection range, causing the tailgate to open late when using a keyless locking system, as they only detect users near the bumper.
Innovation Solution
A coaxial cable sensor unit is designed with a metallic sheathing as the sensor electrode and a copper core of the same electrical potential, utilizing an insulating layer with a specific εr value and a metallic layer for enhanced detection range, and is made watertight to prevent moisture interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-wire electrode sensor unit is used on the bumper, then the device complexity is reduced, but the detection range is limited and only detects users just in front of the bumper
Solution Approach 1:
The patent changes the electrical parameters of the sensor system by using a coaxial cable structure with specific impedance characteristics (50-150 Ohm) and adjustable capacitance values (10-1000 pF). This allows optimization of the detection range and sensitivity without increasing structural complexity, resolving the contradiction between simple structure and extended detection range.
Solution Approach 2:
The coaxial cable structure acts as an intermediary between the control unit and the external environment. The cable's distributed capacitance and impedance characteristics create an extended sensing zone that goes beyond the physical bumper location, enabling detection at greater distances while maintaining a relatively simple overall device structure.
2Length of stationary object
If the insulating layer has a high εr value to increase detection range, then the detection area is enlarged, but the cable dimensions must be increased accordingly
Solution Approach 1:
The patent provides specific parameter ranges for the coaxial cable components: impedance between 50-150 Ohm, capacitance between 10-1000 pF, and insulating layer εr between 1-5. These optimized parameters allow achieving extended detection range without excessive increase in cable dimensions, balancing both requirements.
Solution Approach 2:
The use of insulating materials with specific dielectric properties (εr = 1-5) creates a composite structure that optimizes the electric field distribution. This composite approach allows enhancing detection capabilities while controlling the physical dimensions of the cable within practical limits.
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 increases the detection range of the sensor unit, allowing earlier communication between the vehicle control unit and user's radio key, enabling the tailgate to open as the user approaches.
Implementation Method 1
the sensor unit uses the electrical field generated by the sensor unit to detect the user in an adjacent detection area
Implementation Method 2
the first insulating layer of the coaxial cable has an εr which has a value between 5 and 1. The advantage is that this increases the range of the sensor unit because the electric field creates a larger detection area
Implementation Method 3
the conductor of the coaxial cable designed as a metallic core serving as active shielding. The metallic core of the coaxial cable has the same potential as the first metallic sheath
Data Source
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Figure 5
AI summary
Apparatus for operating a door or hatch on a vehicle, wherein the apparatus has a sensor unit in order to allow detection of an object in at least one detection area which joins the motor vehicle, with the result that the detection can be used to activate the operation of the moving portion, wherein the sensor unit is in the form of a coaxial cable, wherein a conductor of the coaxial cable which is in the form of a metal core is used as an active screen.