Rotating Printed Circuit Gear Position Sensor
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Solution Overview
Problem
Existing gear position sensors for mechanical transmissions are costly to produce and require high tooling costs due to lead frame insertion molding and need multiple electrical wires for communication, with standard potentiometers being insufficiently robust for transmission environments.
Innovation Solution
A gear position sensor using a rotating printed circuit board with discrete resistors and flexing conductive wipers that adjust resistance values, eliminating the need for high resistance materials and multiple wires, and allowing for flexible reconfiguration with low tooling costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lead frame insertion-molded sensor is used, then the sensor structure is robust, but the production cost and tooling cost are high
Solution Approach 1:
The sensor is divided into separate functional components: a robust housing for mechanical strength, a printed circuit board for electrical functionality, and a wiper assembly for sensing. This segmentation allows each component to be optimized independently - the housing provides robustness while the printed circuit board enables cost-effective manufacturing and easy reconfiguration.
Solution Approach 2:
The traditional mechanical lead frame insertion-molded structure is replaced with a printed circuit board-based electrical connection system. The printed circuit board provides both mechanical support and electrical functionality, eliminating the need for complex lead frames and reducing both tooling costs and production complexity while maintaining sensor robustness.
2Adaptability or versatility
If multiple electrical contacts with wipers are used, then gear position can be indicated, but multiple electrical wires are required increasing complexity
Solution Approach 1:
Multiple electrical contacts and wiper assemblies are merged into a single integrated printed circuit board. The PCB provides common power and ground references while incorporating multiple signal traces that connect to the wipers, allowing multiple gear position signals to be transmitted through a single wire harness rather than requiring separate wires for each contact.
Solution Approach 2:
The printed circuit board serves multiple functions simultaneously: it provides electrical connections for multiple contacts, establishes common power and ground references, and enables flexible reconfiguration of sensor output through software or simple hardware changes. This multi-functionality reduces the overall number of wires needed while maintaining comprehensive gear position indication capability.
3Device complexity
If standard potentiometers are used, then a single wire can communicate gear position, but they are insufficiently robust for transmission environment
Solution Approach 1:
The sensor system is segmented into a robust mechanical housing that protects the sensitive electrical components from transmission environment contaminants, and a printed circuit board-based wiper system that provides both robustness and electrical functionality. This segmentation allows the wipers and PCB to be designed specifically for durability in harsh environments while maintaining the simplicity of single-wire communication.
4Reliability
If specialty potentiometers with high resistance materials are used, then sliding wear resistance is improved, but cost and tooling requirements increase
Solution Approach 1:
The traditional mechanical potentiometer with high resistance materials is replaced by a printed circuit board-based wiper system. The PCB provides durable electrical connections through standard trace technologies, and the wipers make contact with the PCB traces through a robust mechanical interface. This substitution eliminates the need for expensive high resistance materials and complex tooling while maintaining or improving wear resistance through the inherent durability of printed circuit board traces and standard wiper contact mechanisms.
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 robust and cost-effective gear position sensor with adjustable resistance values, reducing production costs and enhancing durability by using a rotating printed circuit board with discrete resistors and flexing conductive wipers, which can withstand environmental contaminants and simplify construction.
Implementation Method 1
The insulating substrate includes resistors bridging adjacent coaxial ones of the arcuate conductors to provide different resistances between the arcuate conductors
Implementation Method 2
a first and second flexing conductive wiper positioned within the housing to engage and electrically connect to the adjacent coaxial ones of the arcuate conductors
Data Source
AI summary
A gear position sensor employs a sliding electrical connection between arcuate conductors and flexible wiper arms held on opposite surfaces that rotate relative to each other with the movement of a gear selector shaft. The traces may have multiple segments joined by resistors to provide flexible change in resistance value and resistance range for different applications.