Wheel Speed Sensor Assembly for Sub-Degree Rotation Detection
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Solution Overview
Problem
Conventional wheel speed sensors in vehicles, such as zero turning radius vehicles, have limited resolution, often requiring a wheel rotation of more than 1° to detect movement, which hinders precise speed measurement and control, especially in applications requiring precise movements like autonomous driving.
Innovation Solution
A high-resolution wheel speed sensor assembly is integrated into the vehicle's drive system, capable of generating a wheel speed signal that determines the speed and direction of rotation to within less than 1°, allowing for precise control of the motor based on the received signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wheel speed sensors are used, then the device complexity is reduced, but the measurement precision deteriorates (resolution > 1°)
Solution Approach 1:
The sensor assembly is segmented into multiple functional components: a stationary sensor housing, a rotating hub assembly, a flexible circuit board, and a wheel speed sensor. This segmentation allows each component to be optimized independently while achieving high-resolution measurement capability through the coordinated operation of discrete elements.
Solution Approach 2:
A flexible circuit board acts as an intermediary between the stationary sensor housing and the rotating hub assembly, enabling signal transmission while accommodating relative motion. This intermediary component resolves the complexity of maintaining electrical connections during rotation while preserving measurement precision.
2Productivity
If conventional wheel speed sensors are used, then the ease of manufacture is improved, but the productivity deteriorates (inability to enable precise control)
Solution Approach 1:
The wheel speed sensor assembly is designed to perform multiple functions: measuring wheel speed, determining direction of rotation, and providing signals for precise motor control. This multi-functionality enables the sensor to support advanced applications like autonomous navigation and regenerative braking control, significantly enhancing productivity despite increased manufacturing complexity.
Solution Approach 2:
The sensor assembly incorporates dynamic elements including a rotating hub that moves with the wheel and a flexible circuit board that accommodates rotational motion. This dynamic design enables continuous, real-time speed measurement necessary for high-productivity applications requiring precise control responsiveness.
3Measurement precision
If high-resolution wheel speed sensor is integrated, then the measurement precision is improved (resolution < 1°), but the device complexity increases
Solution Approach 1:
The sensor assembly employs a nested structure where the wheel speed sensor is housed within the sensor housing, which is in turn connected to the hub assembly through the flexible circuit board. This nesting consolidates multiple components into a compact integrated unit, reducing the space required and simplifying installation while maintaining high measurement precision.
Solution Approach 2:
The patent merges the wheel speed sensor, sensor housing, flexible circuit board, and hub assembly into a single integrated sensor assembly. This consolidation combines multiple functions into one device, achieving high-resolution measurement capability while managing complexity through integrated design rather than separate components.
Data Source
AI summary
A motor for a vehicle includes a motor housing, a motor shaft, a hub, and a wheel speed sensor assembly. The motor shaft is disposed at least partially within the motor housing. The hub is configured to be coupled to the motor shaft and to be coupled to a wheel of the vehicle. The wheel speed sensor assembly includes a first end that is coupled to the motor housing and a second end that is rotatably coupled to the hub. The wheel speed sensor assembly is configured to generate a wheel speed signal that facilitates determination of a speed and direction of rotation of the wheel.