Steering Torque Sensor Assembly with Angled Circuit Board
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Solution Overview
Problem
Existing sensor arrangements struggle to accurately determine steering torque and absolute angular position of a steering element beyond a single turn, especially when starting a motor vehicle with autonomous driving or assistance systems, as they require a zero position reference or stored data that may be deleted or incorrect.
Innovation Solution
A sensor arrangement comprising a circuit board with a first sensor element for torque measurement using a magnetically encoded primary sensor and secondary sensor, and a second sensor element employing a Vernier principle with interrelated gears and an angle sensor to determine absolute angular position, allowing simultaneous measurement of steering torque and multi-turn angular position without needing a reference point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic field sensors are placed as close as possible to magnetization regions to improve measurement accuracy, then measurement precision is improved, but device complexity increases due to board design rule constraints preventing component placement near board edges
Solution Approach 1:
The patent introduces a three-dimensional circuit board structure with an angled surface (wing) that extends from the base surface at an angle between 45° and 135°. This dimensional change allows the secondary sensor to be positioned on the angled surface, enabling it to face the primary sensor on the steering element while maintaining compliance with board design rules regarding minimum distances from board edges. The angled surface effectively utilizes spatial dimensionality to resolve the conflict between measurement precision and device layout complexity.
2Ease of manufacture
If a flat circuit board is used to simplify manufacturing, then ease of manufacture is improved, but the distance between primary and secondary sensors becomes too great reducing measurement reliability
Solution Approach 1:
The circuit board is segmented into two distinct surfaces: a base surface that provides mechanical support and compliance with manufacturing standards, and an angled surface (wing) that optimizes sensor positioning. This segmentation allows the board to maintain manufacturability through its standard base surface while achieving reliable sensor measurement through the angled surface that brings the secondary sensor into optimal proximity with the primary sensor on the steering element.
3Ease of manufacture
If standard board design rules are followed to ensure manufacturing standards, then ease of manufacture is improved, but the distance between sensors increases causing measurement to fail
Solution Approach 1:
The patent employs a three-dimensional circuit board configuration where an angled surface extends from the base surface, allowing the secondary sensor to be positioned on this angled surface. This dimensional approach enables the sensor to face the primary sensor on the steering element at an optimized distance, achieving high measurement precision while the base surface maintains compliance with standard board design rules and manufacturing requirements.
4Device complexity
If relative angular position measurement is used to simplify the system, then device complexity is reduced, but the ability to measure absolute angular position during multi-turns is lost
Solution Approach 1:
The patent introduces a gear mechanism as an intermediary between the steering element and the angular position sensor. The gear with teeth engages with the steering element, and as the steering element rotates, the gear rotates proportionally. The angular position sensor then measures the angular position of the gear, which corresponds to the angular position of the steering element. This intermediary mechanical transmission allows the system to measure absolute angular position during multi-turns while keeping the sensor system relatively simple.
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
Enables accurate and immediate measurement of steering torque and absolute angular position during vehicle startup, eliminating the need for stored data and allowing measurement across multiple revolutions without a reference point, enhancing measurement accuracy and reliability.
Implementation Method 1
The magnetic field occurs due to the inverse magnetostrictive effect
Implementation Method 2
The secondary sensor converts changes in the magnetic field of the primary sensor into an electrical signal
Data Source
AI summary
A steering element sensor assembly for sensing a steering torque and an absolute angular position having a circuit board and first and second sensor elements. The circuit board has a base surface arranged perpendicularly to a steering axis and a wing surface angled to the base. The first sensor element determines the steering torque and has a first primary sensor formed as a magnetically coded portion on the steering element and one secondary sensor for converting the changing magnetic field generated by the primary sensor into an electrical signal. The secondary sensor determines the absolute angular position and a main gear arranged on the steering element that meshes with at least two gears, one which has one more tooth than the other. Each gear has a target that faces a respective angle sensor.