Steering Position Rotary Sensor Assembly with Gear Reduction
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Solution Overview
Problem
Current steering position sensors for motor vehicles are costly due to the need for microprocessors to calculate multiple turns of the steering column, and they often suffer from measurement errors and complexity in calculation procedures.
Innovation Solution
A rotary steering position sensor assembly using a gear reduction mechanism with Hall effect sensors and magnetic shields to measure absolute steering angles beyond 360 degrees, simplifying calculations and reducing errors, while utilizing a plastic gear set and housing for cost-efficiency and robust electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a microprocessor is used to determine the number of complete turns of the steering column, then the measurement capability is improved, but the cost and device complexity increase
Solution Approach 1:
The patent replaces the electronic microprocessor-based turn counting system with a mechanical gear reduction system. The gear train with different tooth counts on intermediate gears automatically translates multi-turn steering column rotation into single-turn rotations of the sensor gears, eliminating the need for complex electronic calculation while maintaining measurement capability
Solution Approach 2:
The patent introduces intermediate gears as mechanical mediators between the steering column and the sensors. These intermediate gears with specific tooth counts (e.g., 120 teeth and 40 teeth) serve as translators that convert multi-turn input into single-turn output, enabling turn counting without electronic processors
2Measurement precision
If a microprocessor is used to calculate steering column turns, then the measurement capability is improved, but the manufacturing cost increases
Solution Approach 1:
The patent employs inexpensive plastic gears instead of expensive microprocessors and associated electronics. The gear train components are simple, mass-producible plastic parts that provide the required turn counting function at a fraction of the cost of electronic solutions
Solution Approach 2:
The patent substitutes the expensive electronic calculation system with a simple mechanical gear reduction system that provides the same functional capability at significantly lower manufacturing cost
3Device complexity
If conventional sensors are used without gear reduction, then the device simplicity is maintained, but measurement errors occur in multi-turn applications
Solution Approach 1:
The patent performs preliminary mechanical reduction of the multi-turn rotation before it reaches the sensors. By pre-converting the steering column's multi-turn rotation into single-turn rotations through the gear train, the sensors only need to measure within their accurate single-turn range, eliminating measurement errors
Solution Approach 2:
The intermediate gears act as mechanical mediators that translate the steering column's multi-turn rotation into single-turn rotations of the sensor-mounted gears, ensuring accurate measurements without requiring complex sensor assemblies
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 low-cost, reliable, and flexible sensor system with reduced measurement errors, simplified calculations, and enhanced safety through redundancy, along with reduced size and electromagnetic interference, enabling accurate multi-turn position measurements.
Implementation Method 1
A first magnetic sensor configured to generate, in response to a rotational angular position of the first magnetic quadrupole, a first sensor signal indicative of a first rotational angle of the first rotatable body, a second magnetic sensor configured to generate, in response to a rotational angular position of the second magnetic quadrupole, a second sensor signal indicative of a second rotational angle of the second rotatable body
Data Source
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AI summary
Embodiments herein are directed to steering position rotary sensors including a housing defining an internal cavity, a center shaft extending through the housing, and a gear coupled to the center shaft, wherein the gear is positioned off-center relative to a central rotational axis extending through the center shaft. The steering position rotary sensor may further include a magnet coupled to the gear, a first Hall effect sensor positioned adjacent the gear and concentric with the magnet, and a second Hall effect sensor positioned adjacent the center shaft and concentric with the central rotational axis, wherein the first Hall effect sensor and the second Hall effect sensor are separated by a magnetic shield.