Dual Angular Position Sensors for Wheel Hub Reliability
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Solution Overview
Problem
Conventional wheel hub assemblies with wheel speed sensors are prone to inaccuracies due to environmental factors, leading to false readings and potential safety issues in antilock braking systems (ABS) when sensors or targets become fouled or damaged.
Innovation Solution
A vehicle wheel hub assembly with dual magnetic target tracks and sensors, where a controller compares the output signals from both sensors to generate accurate wheel speed signals and detect potential faults, ensuring reliable data even if one sensor is compromised.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single wheel speed sensor is used in the wheel hub assembly, then the device complexity is reduced, but the reliability of wheel speed measurement deteriorates due to potential sensor fouling or damage from environmental factors
Solution Approach 1:
The single wheel speed sensing function is segmented into two separate sensors. Each sensor independently measures wheel speed, and the controller compares their outputs to detect faults. This segmentation provides redundancy, ensuring that if one sensor is fouled or damaged, the other can still provide accurate wheel speed information for ABS operation.
2Reliability
If dual sensors are installed in the wheel hub assembly, then the reliability of wheel speed measurement is improved through redundancy, but the device complexity and cost increase
Solution Approach 1:
The controller continuously monitors the output signals from both sensors and compares them against each other. When a discrepancy exceeds a predetermined threshold, the system generates a fault indication. This feedback mechanism allows the system to automatically detect sensor failures without requiring complex additional hardware, maintaining reliability while controlling complexity.
3Object-affected harmful factors
If road salt and dirt are present in the wheel hub environment, then the sensors may become fouled leading to false readings, but sealing the sensor region completely would increase manufacturing complexity
Solution Approach 1:
Instead of attempting to completely seal the sensor region against environmental contaminants, the design anticipates potential fouling by providing redundant sensors. If one sensor becomes contaminated and produces false readings, the other sensor serves as a backup, cushioning the system against the harmful effects of contamination without requiring complex sealing 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 dual sensor system provides accurate wheel speed information, reducing the risk of ABS system errors and improving braking performance by differentiating between faulty and functional sensor signals, thereby enhancing safety and reducing braking distance.
Implementation Method 1
a first sensor is located adjacent to the first magnetic target track and configured to sense angular displacement of the first magnetic target track and to produce a first output signal
Implementation Method 2
a second sensor is located adjacent to the second magnetic target track and configured to sense angular displacement of the second target track and to produce a second output signal
Data Source
AI summary
A vehicle wheel hub assembly includes an outer member configured to be mounted to a non-rotatable portion of the vehicle and an inner member rotatably supported in the outer member by a bearing. An annular target body is coupled to the inner member. A first magnetic target track is disposed on the annular target body, and a first sensor is located adjacent to the first magnetic target track and configured to sense angular displacement of the first magnetic target track and to produce a first output signal. A second magnetic target track is disposed on the annular target body, and the second magnetic target track is spaced from the first magnetic target track. A second sensor is located adjacent to the second magnetic target track for sensing angular displacement of the second target track and is configured to produce a second output signal.