Vehicle Wiper Link Mechanism Asymmetric Torque Control
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Solution Overview
Problem
Vehicle wiper devices face challenges in reducing the size of the drive source while maintaining accurate control at the stop position and ensuring a clear field of view for occupants, as existing designs often result in prolonged blocking of the field of view and non-wiped areas due to torque variations and interference with the vehicle body.
Innovation Solution
A vehicle wiper device with a drive source and link mechanism that rotates the wiper back and forth between specific positions, where the torque is greater at the bottom reversing position than at the top reversing position, allowing for a smaller motor and improved control accuracy, and the link mechanism is arranged to reduce interference with the vehicle body by positioning the wiper joint's axis outwardly in the lateral direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the link mechanism significantly increases torque in the proximity of the stop position and top reversing position in a symmetrical manner, then the stop position accuracy is improved, but the wiper speed is lowered in the proximity of the top reversing position which prolongs the time the field of view is blocked
Solution Approach 1:
The patent applies asymmetry by designing the torque distribution in the link mechanism to be non-symmetrical. Specifically, the torque is significantly increased only in the proximity of the stop position (bottom reversing position) while maintaining lower torque near the top reversing position. This asymmetric torque profile allows the wiper to stop accurately at the bottom position without slowing down excessively near the top position, thus resolving the contradiction between stop accuracy and field of view blocking time.
2Volume of moving object
If the drivers are arranged proximal to the lateral ends of the vehicle, then the drive source size is reduced, but the drivers interfere with the vehicle body
Solution Approach 1:
The patent resolves this contradiction by changing the spatial arrangement from a horizontal/longitudinal configuration to a vertical configuration. The output shaft of the drive source is extended in the vertical direction (upward), and the wiper joint is positioned above the drive source. This vertical dimensionality change allows the driver to be arranged near the lateral ends (reducing size) while avoiding interference with the vehicle body through proper vertical positioning.
3Object-affected harmful factors
If the drivers are arranged at inwardly locations in the lateral direction of the vehicle, then interference with the vehicle body is prevented, but the wiper would be significantly inclined outwardly in the lateral direction relative to the front pillar at the top reversing position forming a large non-wiped area
Solution Approach 1:
The patent uses vertical positioning (another dimension) to resolve the contradiction between preventing vehicle body interference and maintaining adequate wiping area. By extending the output shaft upward and positioning the wiper joint above the drive source, the wiper can be arranged inwardly (preventing interference) while maintaining proper lateral positioning at the top reversing position through vertical offset, thus avoiding large non-wiped areas.
Data Source
AI summary
A vehicle wiper device moves a wiper back and forth between a bottom reversing position and a top reversing position. A drive source rotates an output shaft back and forth about a first axis within a rotational angle range of less than 360°. A link mechanism includes a wiper joint coupled to the wiper. The link mechanism rotates the wiper joint back and forth around a second axis within a rotational angle range that is smaller than the rotational angle range of the output shaft. The link mechanism is configured so that torque of the wiper joint is greater when the wiper is at the bottom reversing position than when the wiper is at the top reversing position.