Aircraft Windshield Wiper Sweep Control via Electronic Feedback
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Solution Overview
Problem
Existing windshield wiper systems for vehicles, particularly aircraft, rely on mechanical reversing mechanisms to control wiper blade sweep, which can be restrictive and prone to oversweep, potentially damaging external structures.
Innovation Solution
A windshield wiper assembly utilizing a brushless direct current motor, reversing circuit, and current sensor, coupled with a stop member and keyway mechanism, allows for electronic control of the wiper blade sweep within a predetermined range, preventing oversweep through software-defined limits and overcurrent protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical reversing mechanism is used to control wiper blade sweep, then the wiper blade can be driven back and forth across the windshield, but the system becomes restrictive and prone to oversweep which may damage external structures
Solution Approach 1:
The patent replaces the mechanical reversing mechanism with an electronic control system using a brushless direct current motor, controller, and software-defined limits. The controller electronically reverses motor rotation direction and defines sweep boundaries through software parameters rather than mechanical constraints, eliminating the risk of mechanical failure and oversweep damage to external structures.
Solution Approach 2:
The system incorporates a current sensor that provides feedback to the controller about motor current draw. When the wiper blade approaches the predetermined sweep range limits, the increasing current draw is detected, and the controller automatically reverses the motor direction before the mechanical stop is reached, preventing oversweep and potential damage to external structures.
2Adaptability or versatility
If a mechanical reversing mechanism is used, then the wiper blade movement is restricted, but the device complexity increases due to the reversing mechanism
Solution Approach 1:
The patent eliminates the mechanical reversing mechanism entirely, replacing it with an electronic controller that reverses motor rotation through electrical control. This substitution reduces mechanical complexity while increasing adaptability, as the sweep angle and limits can be adjusted through software parameters without any mechanical modification.
Solution Approach 2:
The system employs dynamic electronic control to adjust wiper sweep parameters. The controller can modify the predetermined sweep range limits and reversal points through software, allowing the system to adapt to different windshield configurations and external structures without any physical changes to the mechanical components.
3Reliability
If electronic control with current sensor is used, then oversweep is prevented through current monitoring, but the device complexity increases
Solution Approach 1:
The current sensor continuously monitors motor current draw and provides feedback to the controller. As the wiper blade approaches the sweep range limits, the mechanical resistance increases causing current draw to rise. The controller detects this current increase and automatically reverses motor direction, providing reliable oversweep protection through simple current-threshold-based feedback control.
Solution Approach 2:
The system uses the motor's own electrical characteristics (current draw) as the sensing mechanism for detecting approach to sweep limits. This self-service approach eliminates the need for separate mechanical position sensors or switches, as the motor's electrical response to mechanical resistance provides the necessary feedback for protective reversal.
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
This solution enables adjustable sweep angles without mechanical hard stops, preventing damage to the wiper system and external structures by limiting rotation electronically and shutting down the motor in case of oversweep.
Implementation Method 1
a brushless direct current motor, coupled to the output shaft
Data Source
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Figure 6
AI summary
A windshield wiper assembly (100) includes a wiper blade (102), an output shaft (106), and a stop member (112). The output shaft is supported for rotation about a rotation axis and is fixed in rotation relative to the output shaft. The stop member is fixed in rotation relative to the output shaft and extends radially from the output shaft to limit rotation of the output shaft about the rotation axis, the stop member thereby limiting movement of the wiper blade beyond a predetermined sweep range of the wiper blade. Windshield wiper systems, aircraft (10) with windshield wiper assemblies and systems, and methods of controlling sweep of wiper blades in windshield wiper assemblies and systems are also described.