Vehicular Pedal Sensor Assembly With Axial Isolation
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Solution Overview
Problem
Existing control-by-wire vehicle pedals lack accurate and reliable sensors for determining the position of the pedal, which is crucial for controlling vehicle functions such as braking and acceleration.
Innovation Solution
A vehicular pedal assembly with a pedal shaft and a position sensor assembly that includes a target element, sensor circuit, and sensor shaft, where the sensor shaft is fixed for corotation with the pedal shaft and isolated from axial movement, allowing precise determination of the pedal's rotational position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the sensor shaft is directly coupled to the pedal shaft, then the structure is simpler, but the sensor accuracy deteriorates due to axial movement interference
Solution Approach 1:
The coupling between pedal shaft and sensor shaft is segmented into two independent functions: rotational coupling (via teeth engagement) and axial isolation (via spacer). This segmentation allows the sensor shaft to rotate with the pedal shaft while preventing axial movement from affecting the sensor, thereby resolving the contradiction between structural simplicity and measurement precision.
Solution Approach 2:
A spacer is introduced as an intermediary element between the pedal shaft and sensor shaft. The spacer acts as a mediator that transmits rotational motion through its teeth engagement while simultaneously absorbing axial movements. This intermediary component enables the sensor to accurately detect rotational position without being affected by axial interference, thus improving measurement precision while maintaining reasonable structural complexity.
2Measurement precision
If the sensor shaft is isolated from axial movement, then the measurement precision is improved, but the device complexity increases due to additional components
Solution Approach 1:
The coupling mechanism is segmented into rotational transmission (teeth engagement) and axial isolation (spacer) functions. This segmentation achieves precise measurement by separating the rotational sensing function from axial movement, while the modular nature of the segmented design keeps the overall device complexity manageable through functional decomposition.
Solution Approach 2:
The spacer is designed to perform multiple functions simultaneously: it acts as a rotational coupling element through its teeth engagement with the pedal shaft, and as an axial isolation element by absorbing axial movements. This multi-functionality reduces the need for additional separate components, thereby improving measurement precision while minimizing the increase in device complexity.
3Ease of operation
If the pedal shaft is allowed to move axially, then the ease of operation is improved, but the reliability of the sensor deteriorates
Solution Approach 1:
The spacer serves as an intermediary that decouples the pedal shaft's axial movement freedom from the sensor shaft. The pedal shaft can move axially freely (improving ease of operation), while the spacer absorbs this axial movement and prevents it from being transmitted to the sensor shaft, thereby maintaining reliable and accurate sensor signals.
Solution Approach 2:
The system is segmented into a movement-permitting section (pedal shaft with axial freedom) and a measurement-stable section (sensor shaft isolated from axial movement). The spacer creates this segmentation, allowing the pedal to operate freely while ensuring the sensor operates in a stable, reliable environment, thus resolving the contradiction between ease of operation and sensor reliability.
Data Source
AI summary
A vehicular pedal assembly includes a pedal housing, a pedal shaft supported by the pedal housing for rotation about a pedal axis, a pedal arm coupled to the pedal shaft pivotable to drive the pedal shaft to rotate about the pedal axis, and a position sensor assembly coupled to the pedal shaft to determine a rotational position of the pedal shaft. The position sensor assembly includes a target element, a sensor circuit that senses the target element and generates a signal, and a sensor shaft fixed for corotation with the pedal shaft. The target element is positioned on the sensor shaft and rotates with the sensor shaft about a sensor axis to move the target element with respect to the sensor circuit and change the signal generated by the sensor circuit. The pedal shaft is movable along the pedal axis relative to the sensor shaft.